9mm ARs

[ysr_racer]

Salt bath nitriding:
https://www.ibccoatings.com/salt-bat...ing-dhn-dhfnc/

Thanks !!

[Mongo68]

NFA lower, NFA side charging upper, taccom bolt, taccom shrouded barrel, jp short stroke buffer. The fun at a match is had by all

[Peahi2]

I have a 9mm CMMG upper and use their magazines. CMMG does great work, and you will pay for it. You also have to wait since a lot of their stuff is on backorder. I haven't really.shot mine so much with 9mm ammo costs the last few years. But it is a soft shooter...no complaints.

[ysr_racer]

Any of you guys with the CMMG set-up in Orange County? I'd love to see one in person.

Thanks

[george223]

I just recently put together a Glock version and haven't had a chance to shoot it yet. I'm kicking around the idea of putting together a Colt type lower. Anybody know of a LGS near HB that might have a stripped CMMG lower in stock?

[Ishooter]

Can you cite some sources on this? I think it's the opposite of what you stated. 9mm is a fast pistol cartridge. It should gain velocity way more than 10". I didn't get a chance to chronograph it, but I'd think it'll be good to 20".

[beanz2]

Can you cite some sources on this? I think it's the opposite of what you stated. 9mm is a fast pistol cartridge. It should gain velocity way more than 10". I didn't get a chance to chronograph it, but I'd think it'll be good to 20".

https://firearmwiki.com/wiki/9mm_Velocity_by_Barrel_Length

So, even for +P hot loads, you lose muzzle velocity past 17"

[Duck Killer]

Can you cite some sources on this? I think it's the opposite of what you stated. 9mm is a fast pistol cartridge. It should gain velocity way more than 10". I didn't get a chance to chronograph it, but I'd think it'll be good to 20".

[j6p2004]

I have the CMMG RDB 9mm bolt barrel kit but not sure whether to use their ARC adapters. Do the CMMG RDB uppers work well with other magazine adapters like Stern Defense or AR-Stoner? Any issue with fte, ftf, or lrbho?

[ysr_racer]

I ordered a cmmg barrel and bolt, estimated delivery...

...September 15th

[Epaphroditus]

Was going to go the AR-15 route but opted for under $500 Mechtech Systems route.

[Ishooter]

https://firearmwiki.com/wiki/9mm_Vel..._Barrel_Length

So, even for +P hot loads, you lose muzzle velocity past 17"

Thanks for the link. I wonder if it has anything to do with the twist of the barrel. If the barrel is longer, then perhaps the twist can be different to bring the best out of it. Chopping off the barrel by the inch and test can only somehow show the basic understanding of it, but there can be other varieties.

[Scotty]

Thanks for the link. I wonder if it has anything to do with the twist of the barrel. If the barrel is longer, then perhaps the twist can be different to bring the best out of it. Chopping off the barrel by the inch and test can only somehow show the basic understanding of it, but there can be other varieties.

The twist of the barrel makes very little difference. The main components to the equation are the friction of the bullet and the pressure curve of the powder. Using a ballistic tool like GRT, it can predict an estimated pressure throughout the barrel. Simplified, the pressure decreases as the bullet moves down the barrel because the volume is getting larger. The friction of the bullet against the barrel requires a certain amount of pressure to move the bullet. At some point, the gas pressure becomes less than the friction force and the bullet starts slowing down. If the barrel is long enough, the friction CAN win out and the bullet will be stuck in the barrel, like a squib.

With blowback AR9, if you don't have enough mass or spring rate to keep the bolt closed, you can have a premature ejection of the case, releasing the pressure and end up with a squib.

[ysr_racer]

Yes, premature ejection can be a problem

[Eat Dirt]

Side Question :

Any love for the Marlin camp 9 ?

Thinking of selling the one I have ......