Lil'Gun for Ruger LC Carbine

[whacamole]

Hope you guys don't mind a long post. I've put even more detail in here than usual because I think my results need to be interpreted with due care. They may prove to be controversial. Do not use the numbers below in your own loads.

Motivated by my earlier testing with Blue Dot, where I was running into manageable but somewhat performance-limiting pressure issues, I decided to look into Lil'Gun. Lil'Gun is said to produce higher muzzle velocities with lower peak pressures compared to other powders. It also meets my safety requirement of filling more than 80% of the case at the loads I am interested in, to more easily detect double charges and reduce the likelihood of positional performance problems and air-gap-induced detonation.

Lil'Gun for the 5.7x28mm has been previously discussed. Some comments include:

"[someone else said] they [Guns and Ammo] used a custom T/C Contender barrel, and that many of those loads were unsafe for use in any of the FN semi-autos"

"very old info I would not trust it"

"[someone else said] the pressure curve is off, and it is not very efficient"

"Where did you hear lil gun was a good powder for 5.7x28? Unless you are shooting 5.7x28 out of a T/C, I wouldnt go near it."

"DO NOT USE Lil Gun for your FSN. You might be able to get away with it for the T/C but certainly not any of the semi-automatic guns. Guns and Ammo did an article a while back using a variety of powders (including lil gun) and they used T/C's. Most of us have concluded that many of those loads are not safe to use in FN weapons....but out of the T/C you should be ok....(SHOULD)."

"Lil' Gun: Too slow burning for blow-back actions."

All comments I found were at least a decade old. None of them presented any data, except in reference to a test done by Guns and Ammo magazine, which I can't find online, and which appears to have been related to developing a load for a 60gr projectile, which is much heavier than I am interested in.

I also looked elsewhere to find information on its use in .410 shotshells and especially the .22 Hornet, where it appears to have achieved legendary status for safety, predictability, velocity, and accuracy. Additionally, I did some modeling with QuickLoad (more on this in a minute), which seemed to bear out the claims of moderate peak pressures at high velocities. I satisfied myself that some carefully thought-out testing was within the risk posture I personally find acceptable.

Throughout this testing, I used unfired Federal American Eagle cases. I recently switched from once-fired to unfired. Pulling the bullets from loaded ammo with a kinetic puller goes fairly quickly with my wife assisting. I also saved some time in not having to deprime and reprime, but I still had to resize and chamfer to get the case mouths and necks in shape. I Dremeled off the decapping pin on one of my Lee full-length sizing dies to be able to full-length size a primed case.

I've determined through testing that the AE OEM primers show pressure signs in much the same way as the CCi 400 small rifle primers. That is to say, they begin extruding around the firing pin at significantly lower pressures than the CCi BR-4 primers, which have a 25% thicker cup. The OEM primers are a mitigation to help me identify excessive pressure early, though if the loads prove unpredictable, I know that might not help me.

My first loads to look for pressure signs were based on the Hammer Hunter 35gr bullet, seated to 1.495" COAL. I've not had amazing results with that bullet in 5.7x28mm, but recent testing and better statistical analysis indicates it is likely somewhat more accurate than the AE round. I would have preferred to do my testing with the Cutting Edge Bullets MTH 32gr, which so far has given me the best accuracy by a noticeable amount, but I'm still waiting for CEB to put that bullet back into production.

I'm adding Tubb Dust to the Lil'Gun.

I also used my MagnetoSpeed Sporter. The Sporter is the cheaper one where the sensing element has to be less than 0.375" away from the bullet as it flies past. You can't do that with the LC Carbine foregrip in place, since it puts the sensing element too far from the bullet's path and makes it impossible to mount the MS, unless you design and 3D print a special mount, which I did, and also use the magnet trick. BTW, regarding the MagnetoSpeed magnet trick, nobody seems to have realized that changing the magnetic flux field is likely to have an effect on accuracy, and it depends on how the magnets are positioned, so for the record I'll just say that I used 6mmx3mm disc magnets, centered by feel on each sensor, and the velocity measurement was ~2% faster (~50 fps at these speeds) than a properly-mounted Sporter that didn't need the magnet trick.

I ran the following loads. Charge weights are as reported by my Lyman Gen6, and are expected to be within +-0.05gr. Velocities are corrected for the 2% error.

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HH 35gr
gr Lil'Gun MV fps
7.9        2293
8.0        2375
8.1        2407
8.2        2320
8.3        2391
8.4        2509
8.5        2424
8.6        2417
8.7        2448
8.8        2442
8.5        2382
8.5        2440
8.5        2367
8.5        2399
8.5        2380

8.5gr average (6 rounds): 2399 fps
8.5gr standard deviation: 28fps

Note the surprisingly high velocity for 8.4gr, and the surprisingly low velocity for 8.2gr. The high velocity for 8.4gr, 100 fps higher than expected, was a little worrisome. Others had warned that Lil'Gun can be unpredictable, especially at lighter loads (FWIW, I have found the same warnings with respect to Blue Dot). I also noted that from 8.5gr to 8.8gr, it looked like velocities had leveled out. I wondered if this was a sign of reaching a maxload situation, or anything else untoward. The best way to make sense of the data, I figured, was to fit a linear regression to it. I find it to be a good way to see the forest for the trees. In this case, I got a predominantly linear relationship between charge weight and muzzle velocity. I've seen this before in other calibers, at least in the range I am interested in (which is, roughly speaking, 80% below maxload through just under maxload).

Throughout all of these rounds, including the 8.4gr outlier, I experienced *no* pressure signs. All rounds cycled and ejected without any issues.

I had previously documented that the Hammer Hunter bullets produce velocity spreads significantly greater than the other bullets I am using. I believe this has to do with the way the bullet seats into the neck. I use an LE Wilson inline bullet seater and a K+M Precision Shooting arbor press, which gives me good feel (literally) during the seating process. LE Wilson doesn't make an inline seater for 5.7x28mm, but I designed and 3D printed an adapter that allows me to use one of their 22-250 seaters for 5.7x28mm. Whereas other bullets have smooth shanks and therefore press in smoothly, the Hammer Hunters have multiple "drive bands" that make the bullet "crunch" into place as the bands click into the neck. I think I am not getting consistent neck friction with the Hammer Hunters. Furthermore, I am finding that to model my real-world results in QuickLoad, I have to enter a signficantly higher "Shot Start Pressure" than the default. So I think I'm getting the equivalent of a lot of neck tension, and it varies a lot. To eliminate this as a possible source of variation, for my next test I switched to Nosler BTLF 35gr bullets, which have smooth shanks and seat smoothly. The Noslers are also one of the more accurate bullets in this rifle. I am not crimping.

Emboldened (maybe that's an inappropriate word) that I hadn't blown the gun up yet, and having seen zero signs of pressure, I expanded my range of loads and got the following results:

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Nosler BTLF 35gr
gr Lil'Gun MV fps
7.0        2215
7.5        2275
8.0        2359
8.2        2329
8.3        2372
8.4        2397
8.5        2457
8.6        2420
8.7        2431
8.8        no reading
8.9        no reading
9.0        no reading
9.1        no reading
9.2        no reading
9.3        2591

I also had two rounds left over with Hammer Hunters:

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8.0gr 2469 (!)
8.5gr 2605 (!)

I got no velocity readings above 8.7gr using the magnet trick, so at 9.3gr I pulled off the foregrip and installed the MagnetoSpeed correctly. This is a giant pain in the rear, because I've squeezed a LimbSaver Sharpshooter X-Ring Barrel Dampener inside the foreguard. Trying to pull the foreguard off with the dampener in place takes quite a bit of awkward pulling and twisting and swearing, not to mention having to then pull off the dampener itself.

Again, I had *no* pressure signs.

I had intended to shoot a few more rounds, but now several things were really nagging me:

- Although velocity hadn't actually flattened out from 8.7gr to 9.3gr, I was missing velocities from 8.8gr to 9.2gr, so I didn't really know what was going on, and that made me uncomfortable.

- The velocities were substantially off from what QuickLoad had been predicting. For example, 7.0gr was predicted to be 1994fps instead of 2215fps. 9.3gr was predicted to be 2686fps instead of 2591fps.

- The 8.5gr load with the Hammer Hunter was 100fps faster than the 8.4gr load from the previous test, which was already 100fps faster than expected, so now I was 200fps off the chart using the HHs. The 8.0gr load was also substantially faster than predicted.

That's when I decided to call it quits for the day. I then spent several hours at home trying to make sense of my results.

I did another linear regression on the Nosler-based data and again got a nice linear fit of charge weight vs muzzle velocity, even across the expanded range from 7.0gr to 9.3gr. The velocity spread had also reduced considerably from the HH-based data.

Still, I couldn't find a way to reconcile QuickLoad with my real-world results. The velocities just weren't lining up with the charge weights across the full range that I had tested. Now, you should never use QuickLoad, on its own, to determine a loading schedule. QuickLoad can become useful once you have dialed in bullet seating dimensions to match a given load and you have captured some real-world velocity data to see how far off QuickLoad is. If QuickLoad is pretty close to your results for a given load, then QuickLoad can predict more results if you don't stray too far from that load.

If QuickLoad isn't agreeing with your real-world numbers, you can experiment with adjusting the propellant parameters. QuickLoad permits this, though they don't exactly encourage it. It appears most people who experiment with this tweak the "Burning Rate Factor", Ba. Increasing Ba will cause QuickLoad to predict a higher muzzle velocity (and a higher peak pressure), everything else being equal. The problem is this: you can dial in Ba to exactly match whatever real-world muzzle velocity you measure for a single charge weight, but QuickLoad might then not match real-world for other charge weights, with the error increasing the further away you get from the point you dialed in. In my case, if I dialed in Ba so QuickLoad matched my 9.3gr result, it would dramatically underpredict muzzle velocity at 7.0gr. And if I dialed in Ba so it matched 7.0gr correctly, it would dramatically overpredict muzzle velocity at 9.3gr. There wasn't even an acceptable middle ground.

In fact, I searched the entire QuickLoad propellant database to see if there was any powder that could match my testing. None of them did.

I believe this is an indication of a significant limitation in QuickLoad's model. I don't mean that QuickLoad has an error. I mean that I think QuickLoad's powder burn model does not accurately reflect some powders when you are trying to get results across a broad range of charge weights. No model is perfect, you just need to understand the limitations of the model, but I can't find any information in the QuickLoad documentation that explains the model with enough detail to understand why it's not working for Lil'Gun, or any other powder, in my testing. I'm guessing, and I believe I am not the only one that has guessed at this, that the QuickLoad Ba parameter is measured for a given powder in a laboratory bomb apparatus that is filled to 100%. If so, then it's less valid the further away you get from 100% fill, at least for some powders. This implies that, without manually varying Ba as a function of fill % based on real-world test data, QuickLoad may only be suitable for fill ranges near 100%, again at least for some powders.

I did find a forum post from someone who presented his own real-world data of using Blue Dot in a .44 Magnum. He observed that velocities increased with increasing charge weight, until they leveled out and then decreased once the charge became compressed.

Then I found a different forum post from another individual working from his own data using Lil'Gun that suggested the Ba parameter in QuickLoad needed to be adjusted in order to better fit a wider range of charge weights, because it appeared the QuickLoad default value was only valid for charges near 100% fill. I tried his suggested value for Ba, but it did not work for my results.

So, out of frustration more than anything else, I decided to figure out what value for Ba was necessary in order to get QuickLoad to agree with my results at each of the charge weights I had tried. To minimize the noise in the signal, I used the linear regression model I had developed for the Nosler. I found I needed the following (not all charge weights shown):

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7.0gr: Ba = 1.1
8.4gr: Ba = 0.96
8.7gr: Ba = 0.92
9.3gr: Ba = 0.885

That doesn't tell me much. Again, you can tweak Ba to match whatever velocity you measure. It's not helpful if it has no predictive power. The numbers above matched the results with the Nosler bullets by definition, but they didn't match the numbers I got when using the Hammer Hunters.

That is, they didn't match until it dawned on me to plot Ba as a function of "Fill %", "Fill %" being the percentage of Usable Case Capacity occupied by the powder. The Usable Case Capacity with the Hammer Hunter 35gr bullet is different than with the Nosler BTLF 35gr. When normalized on the basis of Fill %, lo and behold, I got a straight-line linear relationship between my Ba numbers (which matched the real world) and Fill %. Moreover, that relationship (refined by linear regression) now matched my Hammer Hunter results, with the exception of the outliers, *and* it matched fairly closely the default Ba number from QuickLoad at 100% fill.

For illustration purposes only (don't use these numbers yourself), the table looks like:

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Fill %  Ba
70      1.155
80      1.059
90      0.963
100     0.867

To be useful, I needed to calculate Ba in increments of 1% fill. Using those numbers, I then adjusted Ba for every charge weight value up to 9.9gr and ran it through QuickLoad. QuickLoad predicted that velocity should start leveling off as I approached 100% fill. Peak pressures should remain well below the levels I had previously documented as being damaging to primers, yet I should start clocking some impressive speeds.

Thinking of Lil'Gun (and Blue Dot) in the shotshell and .22 Hornet contexts, the following occurred to me:

- Plastic shotshells are always loaded to 100% fill. In other words, there is no air gap, like you would have in a brass rifle or pistol case with less than 100% fill. The charges might not be very "compressed" per se, but they are constrained, they can't slosh around, and there is no significant air gap.

- The best Lil'Gun loads for .22 Hornet are reportedly all ~100% fill or even compressed. Some have even gone so far as to opine that it may be physically impossible to cram too much Lil'Gun into a .22 Hornet case. The decrease in Ba as Fill % increases suggests that the powder self-moderates, at least to some extent, as the charge becomes constrained and packed.

Encouraged that I now had a model that was matching reality (albeit on not a ton of data), I decided to try a new round of loads. For this test, I used the Lehigh Defense Controlled Chaos 32gr round loaded to COAL=1.580". This bullet had produced accuracy on par with the Noslers in previous testing, it seats smoothly, and the lower weight produces higher velocities while mitigating risk from heavier powder charges.

I tried these loads: 7.7gr, 8.2gr, 8.6gr, 9.0gr, 9.3gr, 9.4gr, 9.5gr, 9.6gr, 9.7gr, 9.8gr, and then 15 rounds of 9.9gr (96% fill) (this time using my Brifit electronic scale to confirm charge weights were within [+0.00g, -0.02gr]). I did not measure muzzle velocity. By this point I had already reassembled my foregrip with the barrel dampener back in place, and I did not have time at the range to wrestle it off and back on again. All I wanted to do was document pressure signs, and if no pressure signs were evident, then I wanted to shoot for accuracy, which required the barrel dampener.

Once more, I had no pressure signs, at least not signs like I was expecting. Two rounds extracted but failed to eject and stovepiped. I'm not going to read a lot into that just yet, because I also had a known-good mild Blue Dot round FTE on me. The rifle hasn't had a proper tear down, cleaning, and inspection for about 300 rounds. I also saw a few dented necks, presumably from slamming hard into the ejection port on the way out. One round had the case body dented so badly that it's now unusable. So you can call those pressure signs. Conservation of momentum says the bolt is going to move backwards at higher velocity due to a hotter round, maybe not initially due to the lower pressure peak with Lil'Gun, but it will experience higher average acceleration due to the higher average pressure as the bullet moves farther down the barrel. As far as the usual pressure signs go, the primers were fine, cases were not getting stuck, and there was no hint of neck cracking or neck separation or base separation. Bullets receded into the case about 0.0005" per previous round fired (half a thousandth).

As far as accuracy goes, it was one of the best groups I have shot, and that's across 15 rounds. SD Radius was 1.0 MOA, matching or beating all previous results except a couple 7-shot groups that beat it out by 0.1 or 0.2 MOA (which could easily be by chance). Furthermore, that was 1.0 MOA in the rain. Raindrops likely opened up the group.

As I mentioned, I didn't measure velocity, which is a significant shortcoming of this test, at least in terms of validating the improved QuickLoad model. At some point I'm going to have to get a MagnetoSpeed V3 (which has a longer sensing range) or a LabRadar. For now, I'm going to be content that my improved QuickLoad model is predicting just under 2700 fps and almost 520 ft-lbs for the Controlled Chaos 32gr+Lil'Gun 9.9gr at COAL=1.580". I'm also going to think about whether I want to back off the charge a tad. I'd be perfectly happy with a 2600 fps round, assuming it's no less accurate. In any event, I'm now shooting 300 fps faster with as good, maybe better accuracy and 100 ft-lbs more energy than my previous preferred load based on Blue Dot that was edging towards pressure issues. It more accurate than, 600+ fps faster than, and 150 ft-lbs more potent than the AE 40gr rounds I started with.

I'm getting more comfortable with the thought that the velocity variations I saw with the Hammer Hunter might be because of a) the neck friction issue I mentioned before, and b) the fact that those loads were down around 85% fill, not up near 100%. Although some of my recent results were looking more promising on accuracy, I think the neck friction issue will steer me clear of loading Hammer Hunters for this cartridge.

A final observation, about the Lil'Gun pressure curve, is that it's a somewhat lower peak but then a firmer push down the barrel after about 3.5", at least based on the QuickLoad pressure vs. distance curves. One commentor wrote: "Too slow burning for blow-back actions" without being more specific. Well, even my weakest loads cycled just fine. Compared to Blue Dot, the pressure peak occurs a scant 0.05" (five hundredths of an inch) further down the barrel. For the same energy delivered to the bullet, it's about 15% lower peak pressure. To duplicate the velocities I am now seeing with Lil'Gun by using Blue Dot, I would have to increase the charge up to a point where I know I would be punching primers. With my Lil'Gun 9.9gr load in the LC Carbine, I am getting 89% propellant burnt and 26.5% ballistic efficiency according to QuickLoad. That's pretty good for a rifle.

Maybe that's a last point I will make. I'm only interested in reloading for the Ruger LC Carbine. I'm uninterested reloading for my Ruger 57, and even if I did want to reload for that firearm, I'd get better results with a faster powder, with a whole lot less unburned powder flaming out the muzzle. In my opinion, I don't think the Lil'Gun load would be unsafe in the pistol, other than setting off forest fires, as the pressure peak is well below True Blue maxloads according to QuickLoad, the pressure-vs-distance profile inside the barrel is lower for the first 3.5 inches (by which point the pressure has subsided significantly), and the pressure peak happens just 0.13" further down the barrel. This depends a lot on random pressure spikes not showing up, of course, and I haven't yet shot hundreds of rounds to really confirm their absence. It also depends on the firearm surviving the recoil.

So don't go running out and start loading 9.9gr Lil'Gun because I said so. That would be a gross misinterpretation of this post. Rather, if I've helped to advance the discussion with new data and, more importantly, an explanation of how I went about things and why I came to my own (limited and error-prone) conclusions, that's great.

[Toprudder]

Thanks for taking the time to share. That is a lot of information to absorb!

[towerofpower93]

My one hold up with tweaking the BA for each charge weight would be, in my experience, 5.7 usually generates a fairly large (60+ fps for 10rds) extreme spread compared to something like .223, 6.5x47L, or even 338LM.

If you're only using one round at each charge weight, and then tweaking the BA to get the numbers to line-up, are you starting with enough data to drive the change?

Apologies if you've found load combinations which give you a tighter ES but welcome your thought process on truing the BA with only a single velocity reading.

[panzermk2]

There is a whole lot here, and thank you for the post.

"I also noted that from 8.5gr to 8.8gr, it looked like velocities had leveled out"

One thing to keep in mind, the 5.7 case does not seal into the chamber like a conventions cartridge.
Essentially while under full pressure the case, your pressure vessel, grows.
So often you will see a point where your are very close to max pressure. You will see test results with no real change, a leveling, in velocities even though there is upwards of .8 gr difference in loads. This is due to the shoulder moving on the case and expanding your pressure vessel while under pressure. The issue becomes is when folks see the pressure level off and think WOW we are safe to go hotter. Then you get neck separations and primer popping out.

Do you keep segregated your brass from each test load. If you do you should see measurable shoulder movement.

[panzermk2]

A note on QL.

All of their models used for their software simulations are based on US government GI/DOD tests that established parameters based off of current, at the time, military loads. Side note, many of these are from WW2, shot at night over a dead calm lake and looking at the impact points in the water, . All of these models are built around standard calibers in locked breach applications.

These simulations all have optimal windows of operation. Example size of pressure vessel,vs powder charge etc. Whenever you get to the outer limits of these simulations they become MUCH less accurate. Another example of the is the POS CED chrono. They brag about their error correction software. Well the CEDs software decides the 5.7 bullet passing through it's screens are 90% of the time errors. This is why if you did back far enough you will come across a picture of a CED unit on the ground with about 20 5.7 holes in it.

I use QL and it is within 2% max real world for me. It took about 2 years and hours editing the code and defaults to get to that point. Part of that process was using my invented chamber pressure system in conjunction with three chronographs (2 pro chrono and an Oehler ) and thousands of rounds spent testing and adjusting.


While QL is great for standard calibers, it is NOT to be trusted by laymen for loading the 5.7.


Side bar, Pro Chrono 2 and the Oehler are the only 2 chronographs worth a fuck for working with the 5.7. I know I have tried ALL of the chronos out there starting 23 years ago. YMMV...................

[towerofpower93]

I'll second the CED chrono sucking for 5.7. I did a number of strings were 2-3 out of 15rds would be picked up.

My LabRadar was the best investment I made for shooting/reloading after a quality bipod. Panzer, have you used an LR with 5.7? Never had an issue with mine.

[panzermk2]

Lab Radar is one I haven't, but Matt Hoffman AKA Buffman RANGE, the guy who makes all those video testing my/EA's ammo, he had one for awhile and did NOT like it and had enough issues he stopped using it and went back to the Pro Chrono II.

So I trust Matt, a LOT, and his opinions. Combine that with my current system that works perfectly so why mess with it. If you did into the forum you will find a very funny, gut wrenching sarcastic rant on how I hate chronographs and in the a detailed list of all the problems.

Irony the cheap Pro Chrono, that has IR LED up gradable screens is hands down one of the best money can buy. I did up grade to their bluetooth versions and their phone app just like the chrono works damn good.

Side bar: I gave my old data link system to Matt so when you watch his ammo reviews the monitor that flashes the FPS is using that set up.

[Toprudder]

A few months ago I purchased a Labradar when they became available again. I installed the app on my iPhone and all worked great. Then there was an upgrade to the app, and I found out there is a known problem with the latest version, it disconnects at random, and the Labradar settings can't be changed without the app crashing. It still works fine manually, though. The user interface on the Labradar itself takes a little getting used to, but once I figured it out, it works well.

I went to the range just today to test some loads, and forgot to bring my Labradar. I had my Caldwell chrono with me so I used that. I have put well over 1000 shot groups across that chrono and it has worked VERY well for me. With the 22cal bullets, I have to shoot closer to center than I do with larger bullets, but that is a minor thing. Not long after I got the Caldwell, I noticed a problem with the app, related to my using an older iPhone (4). I contacted Caldwell and in less than two weeks they had an upgrade in the app store that fixed my problems. I was very impressed with that.

I apologize for contributing to the thread drift.

[whacamole]

Updating from today's testing...

The biggest single fault with my previous testing was that I had not chronographed my muzzle velocities at the higher charge weights, due to my MagnetoSpeed Sporter not really being the right tool for the job. So, based on QL data and my adjusted Ba numbers, I estimated I was approaching 2700 fps.

Now I have a shiny new MagnetoSpeed V3 and it works well for the LC Carbine, once you make an adapter to fit the handguard. My 2700 fps estimate was way off.

I am actually reaching 2900 fps (!).

Here is my sequence today shooting for velocity:

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Lil'Gun   MV
gr        fps
 8.0      2357
 8.5      2538
 8.8      2735
 9.0      2795
 9.2      2812
 9.4      2883
 9.6      2907
 9.7      2902
 9.8      2838
 9.9      2862
10.0      2874
10.0      2874
10.0      2841
10.0      2904
10.0      2891

The load again was:
Never-fired American Eagle brass with OEM primer, full-length sized, chamfered
Controlled Chaos 32gr
COAL=1.580"
Lil'Gun with Tubb Dust
charge weights confirmed to be within +0.00gr, -0.02gr

Again, I saw none of the pressure signs I am used to seeing when loading Blue Dot with soft primers. The primers look fine, just like the SS197SR rounds I fired for comparison. No outward signs of case splitting or separation.

In QuickLoad, to match the muzzle velocities I saw today at 10.0gr, I need to adjust Ba to 0.975. This is significantly different than the adjusted Bas I was calculating from last week's data, which would put Ba at 0.896 for 10.0gr. Remember, however, that today's Ba numbers are with the Controlled Chaos 32gr bullet. Last week's numbers were based off of Nosler 35gr BTLF bullets, which agreed with my Hammer Hunter 35gr results. At least two things are notably different with the CCs compared to the Nosler's and the HHs: 1) 32 gr, not 35gr; 2) the base of the CC is hollow.

Yes, the shoulder is getting blown out and forward. Sampling 5 fired SS197SR, the average base-to-shoulder length is 0.955" (unfired is 0.93"). Sampling 5 of the 10.0gr Lil'Gun loads, the average base-to-shoulder length is 0.980". Also, case necks are sometimes dented.

I will point out that the muzzle velocity is essentially constant from 9.4gr to 10.0gr. Across those 10 rounds, the average velocity was 2878 fps, with a standard deviation of 25 fps. For those who are counting, 2878 fps for a 32gr bullet is 588 ft-lbs, and 2907 is 600 ft-lbs.

All rounds cycled just fine, with two notable exceptions. Separately from the velocity sequence, I fired two 5-round groups for accuracy, loading 5 rounds at a time in the mag. The last of each 5-round group failed to feed. One had a badly scraped case; the other jammed on the nose of the bullet, pushing it off axis and significantly bending the case neck. I am not going to fire either of those rounds. Accuracy was in family with previous Controlled Chaos 32gr handloads, and better than the SS197SR.

"A note on QL."

Thanks, Jay, that's helpful information. I had always wondered where the QL data was sourced.

"even though there is upwards of .8 gr difference in loads. This is due to the shoulder moving on the case and expanding your pressure vessel while under pressure."

Also helpful. Based on the muzzle velocity measurements, and assuming the QL pressure model is sufficiently accurate, I would say peak pressure in these loads is constant from 9.4gr to 10.0gr. QL predicts I should be right around 36000 psi. If the case shoulder is pushing forward 0.050" as peak pressure is reached, that increases the case volume by about 6%, and yes, I can see that makes a substantial difference (increasing maximum case capacity by 6% in QL lowers the pressure peak in my case by about 5000 psi). FWIW, I have no use for hotter loads than this. I really don't even have a use case for a 500 ft-lb load, much less a 2907 fps 600 ft-lb load.

"in my experience, 5.7 usually generates a fairly large (60+ fps for 10rds) extreme spread"

Thanks, towerofpower93. In my experience, the Hammer Hunters and Shock Hammers have produced the worst extreme spreads (126 fps in one test), but the Noslers were comparable to factory loads, even loaded up to 2500 fps, being down in the ~10 fps range. Today's results, using the 10 hottest loads I chronographed, all in the "constant pressure" range, yielded an ES of 69, but it's important to note that the ES of the 5 hottest rounds was only 24 fps. Obviously more data is needed to really characterize the variance.

"welcome your thought process on truing the BA with only a single velocity reading"

That's certainly a valid question. None of this is really what I would think of as "enough" data, not yet anyways. However, for last week's results, it's not really a single velocity reading. Sure, it was one reading at each of several powder charges, but that's how doing a linear regression can be useful. Using linear regression to draw an error-minimized line through the data points means you are using information from all the points in the series, and since they are not *that* far apart, and we have a reasonable assumption that the physics is not ridiculously non-linear (e.g. we are not seeing 50% shot-to-shot velocity differences on a 1% charge increment), then you are effectively combining the information from all the shots to get sort of the equivalent of multiple shots at each charge weight. Regardless, today you can see I did chronograph 5 shots at 10.0gr, and a total of 10 shots in the range where velocity isn't increasing, so I'm feeling a lot better about today's results being a good way to arrive at a Ba value, at least in the 9.4-10.0gr charge weight range when using this particular bullet.

Anyways, this is now a total of 40 rounds using Lil'Gun in the "constant velocity"/"constant pressure" range, at or above 9.4gr, pushing 2900 fps+- (measured, not estimated) out of the Ruger LC Carbine, and I'm not even seeing primer damage. Blue Dot was punching out primers at only 2600 fps. I'm also not seeing pressure spikes, either as evidenced by case/primer damage or by dramatic velocity increases, at least not above 90% case capacity. No, I'm not going to test hotter loads than this. I'm already at 10.0gr=97% case capacity, and I don't need faster than 2900 fps. I will probably back off to 9.5gr as my practical maxload. I have not yet tested this load in once-fired brass, nor with other primers. The shoulder movement is a concern for fatigue and work hardening in that area on reused brass, resulting in separation. Other primers might result in faster or slower powder burn rates.

I suspect the return spring needs to be stiffer in the LC Carbine, and the bolt buffer needs to be more durable and absorb more energy, if I'm going to continue to punish this gun with loads that are 70% more potent than your typical factory rounds.

[towerofpower93]

Seems you're on to some interesting load data, at least for the Ruger carbine.

I wonder how these would do in an AR57 setup with the heavy 8.5oz buffer Toprudder is using for his load development.

Regardless, I'd like to get Panzer's take on how these might operate in an SBR'd PS90 or any of the 5.7 pistols on the market with stock springs. I'm guessing they'd need a little more spring resistance to not get shoulder separations, but I'll stand-by for his opinion. I've held off on getting another 5.7 rifle, since the chopped PS90 is the ultra-compact thing I have hoping for, but the loads you and Toprudder are getting have me wondering if that might change.

[panzermk2]

A few months ago I purchased a Labradar when they became available again. I installed the app on my iPhone and all worked great. Then there was an upgrade to the app, and I found out there is a known problem with the latest version, it disconnects at random, and the Labradar settings can't be changed without the app crashing. It still works fine manually, though. The user interface on the Labradar itself takes a little getting used to, but once I figured it out, it works well.

I went to the range just today to test some loads, and forgot to bring my Labradar. I had my Caldwell chrono with me so I used that. I have put well over 1000 shot groups across that chrono and it has worked VERY well for me. With the 22cal bullets, I have to shoot closer to center than I do with larger bullets, but that is a minor thing. Not long after I got the Caldwell, I noticed a problem with the app, related to my using an older iPhone (4). I contacted Caldwell and in less than two weeks they had an upgrade in the app store that fixed my problems. I was very impressed with that.

I apologize for contributing to the thread drift.

Drift happens, not an issue since you are deep diving into a crap ton of data.

[panzermk2]

Seems you're on to some interesting load data, at least for the Ruger carbine.

I wonder how these would do in an AR57 setup with the heavy 8.5oz buffer Toprudder is using for his load development.

Regardless, I'd like to get Panzer's take on how these might operate in an SBR'd PS90 or any of the 5.7 pistols on the market with stock springs. I'm guessing they'd need a little more spring resistance to not get shoulder separations, but I'll stand-by for his opinion. I've held off on getting another 5.7 rifle, since the chopped PS90 is the ultra-compact thing I have hoping for, but the loads you and Toprudder are getting have me wondering if that might change.

OK SOMUCH here. So since time is an issue for me.

The neck movement to a point is normal. Removing to much of it with springs as an example, well something has to give and it will be the primers or the neck just shearing off with little or no shoulder movement. I have seen this over the years of my R&D.

Lil'Gun I have tested years, well decades ago, and it worked OK for plinkers. Did you do a forum search for it? The forum crashed about 10 years ago and we lost all the older posts including good data. It might have been in there.
The FsN should be fine, PS90, forget the recoil springs, they just speed the bolt back up, it would be the HD rate reducer and HD magazine catch spring upgrade.


Link to search results. LOTS of post, your not the first to want to use Lil'Gun https://www.fivesevenforum.com/sear ... %5D=19

[Toprudder]

The FsN should be fine, PS90, forget the recoil springs, they just speed the bolt back up, it would be the HD rate reducer and HD magazine catch spring upgrade.

I definitely think that the heavier buffer or rate reducer is the way to go. With the extra weight, a lighter spring could be used. I ordered an extra buffer spring just so I could trim it to lighten up the tension - something I will try down the road.

I can tell that the slower rate has improved reliability in my AR57. I’ve had zero misfeeds or function problems since I went with the heavy buffer. The downside is that the extra reciprocating mass is noticeable when it cycles. It is still much smoother and less recoil than my 9mm AR.

[towerofpower93]

Seems you're on to some interesting load data, at least for the Ruger carbine.

I wonder how these would do in an AR57 setup with the heavy 8.5oz buffer Toprudder is using for his load development.

Regardless, I'd like to get Panzer's take on how these might operate in an SBR'd PS90 or any of the 5.7 pistols on the market with stock springs. I'm guessing they'd need a little more spring resistance to not get shoulder separations, but I'll stand-by for his opinion. I've held off on getting another 5.7 rifle, since the chopped PS90 is the ultra-compact thing I have hoping for, but the loads you and Toprudder are getting have me wondering if that might change.

OK SOMUCH here. So since time is an issue for me.

The neck movement to a point is normal. Removing to much of it with springs as an example, well something has to give and it will be the primers or the neck just shearing off with little or no shoulder movement. I have seen this over the years of my R&D.

Lil'Gun I have tested years, well decades ago, and it worked OK for plinkers. Did you do a forum search for it? The forum crashed about 10 years ago and we lost all the older posts including good data. It might have been in there.
The FsN should be fine, PS90, forget the recoil springs, they just speed the bolt back up, it would be the HD rate reducer and HD magazine catch spring upgrade.


Link to search results. LOTS of post, your not the first to want to use Lil'Gun https://www.fivesevenforum.com/sear ... %5D=19

I had not searched on it, but I do remember the reloading data loss from the crash being a real bummer. Grantness and iFire put a ton of data up that seemed to have been partially lost, but I also haven't messed with new loads for my PS90 in almost 7yrs at this point.

Thanks for the insight on your Lil' Gun results and hypothesis.