AR in 9mm

[eighteenninetytwo]

I was considering getting an AR in 9mm. Couple of questions.
- Firstly anyone got one of these?
- Can I just plonk the upper onto my Standard lower?
- Are there any issues with feeding a snub nosed bullet instead of the 5.56? I assume the feed ramps are significantlly different?
- What Mag is used and how is it attached? does it sit inside the standard AR mag casing?

[spareparts]

I don't have one but I've been looking in to getting one for a while and did a little looking around.

1. In some cases you can just plonk on your lower but most of them require that you change out the hammer for a 9mm hammer. In some cases you'll have to change out your buffer as well.

2. Not sure on feeding as I haven't acquired one yet.

3. The mags are usually sten or uzi mags and require a magwell adapter. There are some mags floating around that already have the adapter welded to the magazine.

These issues plus the price have kept me from doing it so far.

[TMC]

I was considering getting an AR in 9mm. Couple of questions.
- Firstly anyone got one of these?
- Can I just plonk the upper onto my Standard lower?
- Are there any issues with feeding a snub nosed bullet instead of the 5.56? I assume the feed ramps are significantlly different?
- What Mag is used and how is it attached? does it sit inside the standard AR mag casing?

I have one, an Olympic

Olympic uppers work on any lower that will shoot 223 (no changes needed). All of the others require different lower parts (hammer, buffer, spring, special mag inserts, etc.)

Mine feeds any ammo, round nose, lead, hollow points.

Mine is on a registered lower so mag attachment is like any other AR mag.

The mags fit in like a 223 mag.

Olympic's upper use old Sten Mags, either with and adaptor which locks into the mag well or modified by Olympic who welds a small piece on the back of the mag which has the mag catch notch.

The other uppers use Uzi or specially made 9mm AR mags.

[Dirtbiker]

I have a RRA 9mm upper on a LAR multi-cal lower, but any lower will work. The RRA system is the same as Colt.

Your lower will require a mag block. The RRA block simply slides into the mag well and is held in tension by a friction lock.

If your 5.56 parts kit came with a rounded top hammer it will work as is. If your hammer has a sharp top edge you should change it out to the 9mm hammer ($20 and 2 mins work). If you are building your own 9mm upper just use a CMMG ramped 9mm bolt and it will work with any hammer on the market.

9mm buffers are unique to themselves so it will need to be changed too. Brownells sells a 9mm conversion kit that includes everything for the lower mag block, hammer, buffer and spring ($175) The buffer and spring work in carbine tubes w/o mods. If you run an A2 stock (like me) you need a short delrin spacer. (available at Brownells too)

RRA uppers can use slightly modified UZI mags, Colt mags, RRA mags or C/products mags.

The uppers just snap on like any other. My 9mm is very light. Even though the barrel looks heavy it has a big hole in it opposed to 5.56 (about 62% larger). Standard barrel dia is .750. My M4 profile 5.56 rifle is configured exactly the same as my 9mm and it feels nose heavy compared to it. 9mm uppers are blow back so there is no gas tube.

I shoot just about anything through mine, it all works great. There is an ammo savings but not that much. 9mm wolf is $200 per 1K 5.56 wolf is $250 per 1K. Hopefully ammo will continue to fall. 9mm is dirt cheap to reload so the savings goes up if you have the equipment.

[Bladewurk]

If you run an A2 you don't need to change any buffer or spring usually the standard rifle buffer will work fine, the spacer is needed only if you run the shorter carbine length buffer in a rifle length tube..

I have a RRA 9mm upper on a LAR multi-cal lower, but any lower will work. The RRA system is the same as Colt.

Your lower will require a mag block. The RRA block simply slides into the mag well and is held in tension by a friction lock.

If your 5.56 parts kit came with a rounded top hammer it will work as is. If your hammer has a sharp top edge you should change it out to the 9mm hammer ($20 and 2 mins work). If you are building your own 9mm upper just use a CMMG ramped 9mm bolt and it will work with any hammer on the market.

9mm buffers are unique to themselves so it will need to be changed too. Brownells sells a 9mm conversion kit that includes everything for the lower mag block, hammer, buffer and spring ($175) The buffer and spring work in carbine tubes w/o mods. If you run an A2 stock (like me) you need a short delrin spacer. (available at Brownells too)

RRA uppers can use slightly modified UZI mags, Colt mags, RRA mags or C/products mags.

The uppers just snap on like any other. My 9mm is very light. Even though the barrel looks heavy it has a big hole in it opposed to 5.56 (about 62% larger). Standard barrel dia is .750. My M4 profile 5.56 rifle is configured exactly the same as my 9mm and it feels nose heavy compared to it. 9mm uppers are blow back so there is no gas tube.

I shoot just about anything through mine, it all works great. There is an ammo savings but not that much. 9mm wolf is $200 per 1K 5.56 wolf is $250 per 1K. Hopefully ammo will continue to fall. 9mm is dirt cheap to reload so the savings goes up if you have the equipment.

[Josh3239]

9mm blocks come with their own feedramps built in.