Oh just glueing my $1200 gun back together…

[trevorstuart24]

So my frame is cracking significantly and I’ve read another post in the past where this happened in the same spot. FN denied their warranty claim because they modified the magazine spring and polished the sear . I’ve done that as well, placed an EA trigger, used an EFK barrel, a regular barrel with ea spring, a light on the rail, and a red dot. So plenty of reasons FN would deny my claim as well which is why I’m not attempting to ship my only gun away. And I’m not bothering to mod it back to stock because that would involve more work and money than my attempted solution; plastic weld glue.

I don’t notice any flex in it yet so hopefully it survives but I doubt it will. No more light is the only other change I’m making. Yes, I reload 40gr around 5.8 gr true blue so maybe the frame can’t handle that. About 10k rounds. I can say without a doubt I won’t be buying another. Maybe another frame but I don’t think that’s possible. I also don’t think the mk3 has been beefed up in that spot. I know the mk2 was but that’s what I’m glueing back together. Frustrating!





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[panzermk2]

What light? This is the first I have seen of this in a MKII with the beefed up front frame.


Also next time reach out, I have this wicked ass, and HOLY fuck expensive carbon fiber epoxy resin I use for fixing FsN frames.
Most of the time I use it for USG rails that have come loose and un fucking gunsmiths who know what they are doing frame damage, most often from them forcing the hammer pack pins out and chewing up the rear of the frame.

[panzermk2]

And you are using the correctly lugged MKII compatible EFK barrel? YES I have to ask just to cover bases.

[trevorstuart24]

What light? This is the first I have seen of this in a MKII with the beefed up front frame.


Also next time reach out, I have this wicked ass, and HOLY fuck expensive carbon fiber epoxy resin I use for fixing FsN frames.
Most of the time I use it for USG rails that have come loose and un fucking gunsmiths who know what they are doing frame damage, most often from them forcing the hammer pack pins out and chewing up the rear of the frame.

It was the stream light tlr-1. You have actually seen this before: https://www.fnforum.net/threads/im-done ... -7.204618/

The glue i used is rated for 3770 psi. We shall see if that’s enough.

It’s hard to see from that second pic I originally posted but the crack is also between the two notches the barrel rides between as well as on the bottom of the posterior side near where the cam sits. That’s where I originally noticed the crack and I believe that developed before I ever installed the efk barrel. I’m not certain on the timing though.

I believe it’s the mk3 efk barrel. That was the only one listed on their site when I purchased it. I’m attaching another pic:



I believe this is a design flaw in the weapon and I don’t think it’s appearing frequently because most people aren’t putting high round counts through it. I know you are an exception jay.

I don’t know a lot about gun smithing but it seems like the barrel catch spring is underpowered, too far back, or both. Clearly too much energy is being transferred to the plastic frame. At least under the conditions I’ve been shooting: 40gr, somewhat hot, accessories, etc.

[panzermk2]

WOW I did not realize it was the same gun/post.

I see a lot of stuff and can't always remember.

Yep MK2 barrel, you look for the small cut out above the large cut out on the lug.


The relief for the barrel return spring used to be in the frame and it was a weak spot. So they tripled the thickness of the rib and moved the relief to the barrel lug. A MUCH better designed.
I talk about the frame and barrel lug differences here,
https://youtu.be/Unzjsr_4VAg?t=1114

FYI For years now all EFK barrels have come with a 20 pound spring, matching EA's 20#, over the OEM 18.

Still sucks to see this, I have not seen this failure on a MK2 yet. That is not to say someone hasn't put a over slide scope mount on one and broken it off, it's just not something I have seen a lot of. Not to brag but most folks know after the have modded their pistols FNH's is just waiting to void their warranty so they end up with me to be fixed. N

[trevorstuart24]

No worries, I figured it slipped your memory.

Yea I noticed efk’s spring was also slightly longer and thicker than yours(by about 3 thousandths). I didn’t have any way to measure tension but I’d imagine theirs is a little heavier unless it’s a different steel. Their finish was rough compared to yours so maybe it’s a matter of polished vs unpolished.

I also found it interesting that the shoulder bump in efk’s chamber is significantly smaller than the stock barrel(less pronounced).This can be easily seen looking down the chamber or at a fired case. Not sure why they did this.

Either way i would be surprised if 2 lbs of spring tension is the straw that broke the gun. Sped it up, sure, but I’d imagine it would happen regardless, on account of this occurring in a stock pistol spring as well.

I shot the gun today and had my best 5 group SD of 3fps so it’s not done yet but we will see. Still working on my load so hopefully I find it before the gun falls apart. I know you’re probably thinking why would I keep working on it after 3fps but I’m obsessive and hard to satisfy. Which is why I’m definitely not buying a replacement FN. Maybe the rock, but I’d like to hear more on its reliability and accuracy.

[trevorstuart24]

So plastic glue did not hold up. I removed it and put a ton of jb weld in there. So we will see if the jb weld is the key and I’ve designed the mk4 or it’s the mkay fuck this.

[panzermk2]

JB might not hold up well. It's shear strength is an issue.

[blueorison]

The pictures aren't showing up; I wonder how the Mk3 will compare; but if they are using the same frame design on the front...

[trevorstuart24]

The pictures aren't showing up; I wonder how the Mk3 will compare; but if they are using the same frame design on the front...

Yea I wonder the same. I know jays video shows they beefed up the side frame by a mm or 2 but that’s not the point of failure here. It’s that polymer between front metal slide and the cam. Point of contact is the front of the slide on the polymer at full slide retraction.

Not sure about the pics, they show up for me on multiple devices. The jb weld started failing so it’s devcon next with some better polymer prep