9mm Submachine gun ammo

[alelord]

Hey Everyone,

Just posting about the time I played around with some home-loaded 9mm sub gun ammo.
I used an AR-9 that I built with a 8.5in barrel, 10.5 OZ buffer, a heavy 308 trigger kit, and a 338 Lapua recoil spring. The recoil spring makes it super stiff in a straight blow back with about 15-20 pounds to charge the gun.

Now on to the fun stuff. Yes, I know it's pretty risky to push 9mm this hot (and probably pretty stupid), but I did a standard 9mm case with a Winchester small rifle primer, 7.5 grains of AA7 powder with a 147 grain FMJ on top, and COAL was 1.150 in. According to Quick Load it should go about 1300 FPS and be about 46K PSI. Please note that if the gun is not completely in battery you WILL have a case blow out on you. I also talked to a few buddies about the AR platform and they said that the platform itself should be able to take standard 556 psi if you can keep the bolt closed long enough.

It is super fun to shoot. It sounds like you are shooting hot 115 grain loads and because of the heavy recoil spring and platform there is not a lot of recoil but it is sharp. It has no problem pushing that recoil spring and the 10.5OZ buffer back.
I hope this helps anyone looking to load 9mm super hot and please be careful when working up way above max PSI for any caliber.

Thank you all,
Alelord

[WinchesterM1]

I HAD a Sterling SMG that would not cycle with anything less then a 9mm+P++ I used a lee 124 over 5.4 grn of unique and it would cycle 90% of the time


I also used Speer 9mm+P+ brass though not standard 9mm

[Texas by God]

Sounds like you need to move up a mm to 10. To be safe.

Sent from my SAMSUNG-SM-G930A using Tapatalk

[Pioneer2]

For the record the Germans used to prefer captured Canadian 9mm ammo as it was loaded hotter than the crappy British stuff and worked dandy in all their guns.

[nueces5]

I once had to shoot ammo from SMG manufactured by a military company, and they were very hot

[Drm50]

Back in 70s I was young & dumb and I ruined a new S&W m39 with French 9mm Military for SMGs.

[Lloyd Smale]

I never am a cheerleader for using over book loads. that said with your set up you should be able to eat plus p like candy. You already addressed the big points. A heavy hammer spring, buffer and buffer spring. Only thing I can add is buy yourself a Wilson bullet proof firing pin, make sure you using a good quality bolt that runs as smooth as possible and go with one of these https://taccom3g.com/product/taccom-...ower-feedramp/ the smoother the transition into the barrel the better chance its not going to fire out of battery. Most 9mm ar15 barrels have a real steep forcing cone. I even went with a faxon barrel because they do have a better feed ramp. But if I was going to do it again Id go to taccom and buy one of there ramped barrels and bolts made to use it. Bottom line though is mine with the faxom barrel and taccom feed ramp even feeds soft hps a 100percent. Something it never did when I got it from psa.

[Petrol & Powder]

The OP's rifle still retains a hammer. So even if it is a straight blowback with no bolt locking system, it is far less likely to fire out of battery.

Many submachine guns simply have a fixed firing pin that impacts the primer as the bolt closes. Ammunition specifically made for submachine guns is frequently loaded to higher pressures than standard 9mm ammo indented for pistols AND that ammo often has harder primers.

Some submachine ammo is significantly hotter than standard pistol ammo !

[greenjoytj]

Is there a SAAMI Pressure specification for 9 mm ammo that is intended for use in submachine guns? Would these hotter cartridges be specially marked to identify them so they wouldn’t get loaded into a handgun?

[Petrol & Powder]

9mm Submachine ammunition is over SAAMI pressure specs. Because the "S" in SAAMI stands for "Sporting" and submachine gun ammunition is almost exclusively military issued ammunition, there are no SAAMI specifications for military submachine gun ammunition.

Most military submachine ammunition is designated as such by some means but not always on the cartridge itself. I believe the Israelis used a color code and I think the French just marked the packaging but I'm not sure. Maybe someone else can provide some input.

There are military standards for small arms ammunition, NATO being one of the more well known, but those standards often vary by country or group of countries.

[Petrol & Powder]

And by the way, for those of you that were around and paying attention to the M9 Beretta pistol trials and related U.S. adoption of the Beretta back in the 1980's - do you remember the early failures of the Beretta 92 [M9] due to over pressure ammunition?
Some of the "failures" were the direct result of downright sabotage by people that wanted the pistols to fail. I'm sure some of the submachine ammo found its way into the pistols by accident but some was proven to be intentional.

[nueces5]

https://saami.org/wp-content/uploads...-2-18-2019.pdf

[smkummer]

If your AR15 platform 9mm doesn’t have stainless hammer and trigger pins, it’s probably only a matter of time before you break them. The AR platform runs with mild 9mm ammo. 9mm nato should run in any open bolt sub gun and also not hurt a M92 or any modern 9mm handgun with a good recoil spring. No way would I shoot some of the Egyptian or Israel sub gun ammo in my handguns.

[trapper9260]

How would this 9mm nato ammo work in a Cobray M11/9 , would it be safe? Not to go off the OP .

[Lloyd Smale]

I guess I don't understand that. Ive shot probably 50k through 9mm ars with steel (not stainless) pins. Pulled them a part many times and saw no wear. I would have to think that if there getting beat they would beat the aluminum of the holes in the lowers before the pins themselves. I do put locking pins on mine though because the blow back guns seem a bit for suspectable to pin walk. I did break to firing pins in my cmmg gun (before I had the psa gun) and put a Wilson bullet proof pin in it and never had a problem since. When I got the psa gun I put a Wilson pin in the gun and stuck the one I pulled out in the magpul grip for just in case.

If your AR15 platform 9mm doesn’t have stainless hammer and trigger pins, it’s probably only a matter of time before you break them. The AR platform runs with mild 9mm ammo. 9mm nato should run in any open bolt sub gun and also not hurt a M92 or any modern 9mm handgun with a good recoil spring. No way would I shoot some of the Egyptian or Israel sub gun ammo in my handguns.

[Petrol & Powder]

An AR platform set up as a 9mm and blowback operation is really nothing more than an overgrown submachine gun that fires from a closed bolt. The bolt and bolt carrier provide the mass. The recoil spring and buffer in the buffer tube perform the same function as the recoil spring in a regular sub gun. The hammer may provide a little resistance to the rearward movement of the bolt as it is rocked back, but the hammer pin isn't under additional stress compared to a conventional AR set up.
I agree with Lloyd, I'm not sure how the hammer pin and trigger pin would be subjected to any more stress in that configuration.

[smkummer]

I have a registered Colt M16A1. I slapped on 9mm colt smg upper with a Colt mag. well adapter. So I am shooting full auto in 9mm. Within 1-2K rounds, my original hammerpin broke. I installed the stainless pin from the smg parts kit and it has lasted since. If your not shooting full auto, you may be fine, but again, the full auto original colt 9mm smg, came with factory stainless pins.

A 9mm AR utilizes a 1 piece bolt that is unlocked, there is no separate carrier. Comparing it to a open bolt smg, it is far lighter. It relies on the heavy buffer to somewhat equal the mass needed to work with an unlocked 9mm cartridge.

WinchesterM1, I had a sten MKII that needed over pressure loads to function properly. When I replaced the barrel, it would run with winchester white box ammo. The barrel was shot out. I have a friend with a S&W76 who experienced the same situation of which a new barrel solved his issue.