Subsonic reloading for Bolt Action

[lokichoki]

Hello new to the Forum,
I am not new to reloading but I know 5.7 is a different beast and my dies are OTW so I have some questions I was hoping if anyone has any experience with this. I have a Dark Mountain Arms Stowaway bolt action, since it's a bolt action I was curious of a couple things.
Has anyone neck sized 5.7? If I can avoid FL sizing I can prolong my cases life. I'm assuming a .223 neck die cut down can work
Anyone reloaded a cast 55gr LRFN boolit? How has stability been in this weight, the Stowaway is the same twist as every 5.7.
Thanks in advance for any info

[panzermk2]

Welcome to the forum.


You're in new territory with that gun.

Yes it's a bolt gun and often with bolt guns for match loads you just neck size.

Not sure this rifle and here is why. When you fire the 5.7 from a locked breach you run extremely hi pressures.


The 5.7 was designed around a blowback action. When you fire SS197 from a locked breach system, as in bolt action, you go from the normal pressure of around 38-43K PSI to 120k PSI.
So one thing I have seen so far is the massive bolt lugs to help deal with this.

I suspect they might have done something with the chamber. If you are familiar with the .308 CETME fluted chamber that causes sizing issues, I wonder if the chamber is fluted in some way to deal with the hi chamber pressures. If the chamber has some form of contouring to help deal with pressures you would have to full length size.

[Buffman]

Wouldn't that kind of case pressure show on extracted cases?

[lokichoki]

The chamber is not fluted, the spent cases are pristine. I plan on trying very low pressure loads I will probably start with Trail Boss just to see stability and velocity, I would guess slower shotgun powders could be used. As for the locking lugs there pretty tiny, idk how to post photos on here but I will follow up on here as this platform is the only one

[Buffman]

IMO If I were you: 3.4gr of AA #7 for the pistol and or 3.3gr of AA#7 for the 16" But those loads are for semi-autos. That's for a 55gr FMJ

[panzermk2]

The chamber is not fluted, the spent cases are pristine. I plan on trying very low pressure loads I will probably start with Trail Boss just to see stability and velocity, I would guess slower shotgun powders could be used. As for the locking lugs there pretty tiny, idk how to post photos on here but I will follow up on here as this platform is the only one

The are large for a 22cal rifle.

[panzermk2]

Wouldn't that kind of case pressure show on extracted cases?

Not always. Sometimes firing pins will get stuck.

[panzermk2]

The chamber is not fluted, the spent cases are pristine.

That does not mean there isn't something the chamber and unless you start measuring things just looking at them with the naked eye doesn't always tell you everything.

[caseylain99]

When you fire SS197 from a locked breach system, as in bolt action, you go from the normal pressure of around 38-43K PSI to 120k PSI.
So one thing I have seen so far is the massive bolt lugs to help deal with this.

Do you have any proof of that? Like actual pressure sensor data? Because that sounds highly unbelievable.

[panzermk2]

OK so you have no clue who I am. So to not rely on a stated argument to authority logical fallacy.

I am Pr/CEO of Elite Ammunition. I started manufacturing 5.7 and inventing now bullets for it over 20 years ago. I hold multiple patens for 5.7 projectiles and have manufactured over 20 millions rounds of NEW virgin brass 5.7 ammunition including designing and manufacturing my own improved version of 5.7 brass. COVID killed my in house brass manufacturing.

First you need to understand how the 5.7 cartridge works. As a cartridge it was designed to function differently from standard ones.

The video starts at the point of detailed explanation on how the 5.7 cartridge works.
https://youtu.be/RiO-NgyIBLA?si=GK9 ...

My data comes from my pressure testing system that I invented over 15 years ago after I discovered that a standard universal receiver and Bill Wiseman pressure barrel do not in any way give results that can be used.

This is also why CMMG and Ruger have zero issues with full power 5.7 as I supplied R&D and proofing 5.7 ammunition to them.

PSA initiated contact but never followed up and to no surprise to me have the issues with their pistol's cam breaking.

[lklawson]

NEW virgin brass 5.7 ammunition including designing and manufacturing my own improved version of 5.7 brass. COVID killed my in house brass manufacturing.

Plans to bring it back?