9mm AR, blowback or DI?

[carbon9]

I went to a local pistol caliber carbine/shotgun match and my friend brought an HK 94. It made me decide to buy/build a 9mm carbine. There doesn't seem to be anything on the market like an HK 94 anymore except for imitations. The Beretta CX4 Storm is lacking several things, the camp rifles don't do it for me, nor does the KelTec. I think it would be fun to build something which is actually semi-accurate as this will not be a full auto weapon. I am thinking of a 14" barrel with pinned flash/comp/whatever or a threaded 16".

There seem to be two different camps on barrel twist and operating system.....

There is the standard 9mm blowback operating system and then a few companies like Rock River are doing Direct Impingement operating systems. Has anybody compared the two? What were your impressions?

Barrel twist seems to be 1:10 (Rock River, Colt, CMMG, etc.) or 1:16(Olympic Arms, Beretta Storm) Which would be more accurate to 100yds with 147gr? I have searched everywhere and both camps never give a valid answer as nobody seems to really care and I have yet to find an equal comparison. Just the typical blind buyers pride ( i bought this so it MUST be the best).

I would like a Stainless, Nitride or at the least a chrome lined barrel. I only want to go through this once. Oly seems to be the only company making a stainless barrel, everything else seems to be Chrome Moly. I could always Nitride the Chrome Moly but would hate to waste the $$$$ if 1:10 twist isn't as accurate as the 1:16.

Last of all, the damn plethora of mag choices and conversion blocks! Uzi, Sten, Colt, Glock, etc. Then there are the Oly .223 sized mags with the block built in and no conversion or mods to your lower needed. I wouldn't have to get used to a different feel between my .223, 9mm AR and my upcoming NC .22 upper for mag changes. Any experiences with any of these?

Man, I thought the AR-15 were bad enough with all the options out there. At least the AR-15 has "milspec" to follow. 9mm AR is a nightmare!

P.S.

Don't even get me started on the 7.62 x 25 conversions(kinda cool and cheap ammo, 1260rds for $90).

[DyNo!]

I didn't realize there was a DI 9mm. Are you sure about that?

[GentlemanJim]

I didn't realize there was a DI 9mm. Are you sure about that?

I have not seen one, the RRA 9mms I have had were blowback

A little mag work makes a big impact on reliabiity

Jim

[MI_Packer]

I picked up a RRA 9mm carbine earlier this year - it's blowback operated.

Purpose built for 9mm, no adapters.

4.4 grains of Titegroup under a 124 gr HP Montana Gold is 1.5 inches high at 55 yards and 1.5 inches low at 100 yards. Perfect for some of the ranges I shoot at regularily.

edit to add - no problems with Colt or Brownells mags. I have one plastic mag that doesn't work very well and I can't remember the brand off hand. PM me if you need that info.

Edited December 26, 2010 by MI_Packer

[carbon9]

I didn't realize there was a DI 9mm. Are you sure about that?

I have not seen one, the RRA 9mms I have had were blowback

A little mag work makes a big impact on reliabiity

Jim

When it comes to 9mm ARs I am not sure about anything Looking at the Rock River site I noticed they offered a carbine and mid length 16" 9mm and ASS U ME D it was similar to a gas system .223. Must just be the handguard length and/or mounting point for the sight block. Thank you for the correction.

[carbon9]

I picked up a RRA 9mm carbine earlier this year - it's blowback operated.

Purpose built for 9mm, no adapters.

4.4 grains of Titegroup under a 124 gr HP Montana Gold is 1.5 inches high at 55 yards and 1.5 inches low at 100 yards. Perfect for some of the ranges I shoot at regularily.

edit to add - no problems with Colt or Brownells mags. I have one plastic mag that doesn't work very well and I can't remember the brand off hand. PM me if you need that info.

Thank you for an actual accuracy and reliability report.

[jaredr]

I didn't realize there was a DI 9mm. Are you sure about that?

I have not seen one, the RRA 9mms I have had were blowback

A little mag work makes a big impact on reliabiity

Jim

the fellow who runs teppo jutsu (marty i think is his name) wrote a while back about developing a DI upper for 9mm to avoid what were apparently problems with broken bolt catches associated with blowback 9mm. i don't know if anything came of it or if it was actually ever sold.

to the OP, my experience with my RRA upper and hahn block has been very positive, but pls note that I used it only for casual plinking so round count is low (probably around 2000 rds total over a few years) and never did any formal bench testing for accuracy on paper. i use pro-mag 32 round magazines and actually never had any feeding problems, though I understand others have had poor experience with this brand. i ended up using the 9mm AR mostly as the garbage can for leftover 9mm +P and 9mm major loading experiments. Do not have notes on 9mm major handy but used a lot of 6.8gr Alliant Power Pistol and 115gr FMJ and they worked fine ("worked" means I was able to sight in a red-dot and bounce cans on a 50 yard range, not very stringent accuracy requirements). Also used a lot of 147 gr tuncated cone lead over WW231 (do not have load data handy but recall projectile and powder). Load was dirty, but functioned fine.

[caspian guy]

I think you'll find all of the commercialy avaliable 9mm ars are blowback. I read a thread on arfcom where a guy had built himself a di 9mm upper, he ended up with a gas port position almost on top of the chamber to get enough gas to run the gun. I believe he still said it was very sensitive to powder choice and load to get it to run. (I believe he was running a large charge of slow powder, kinda analogues to a major 9 load). If I can remember I'll try to find and link the thread.

[OPENB]

I have an Oly 9mm flat top I got from Midway. I got a tax stamp and SBR'd it to 11.5". I put a Primary Arms Micro dot with a riser, and a Yankee Hill folding rear sight on it, and zero'd at 50yards. With my major 9mm ammo, it is 1" low at 100yards. I use the Hahn block that allows use of unmodified Sten mags, which I bought a boatload of when they were $1 each. I had a couple cut down to 20rds. for easier use on a bench with a shooting bag. I read up on 9mm's on ar15.com, and decided on the Oly system. Has been 100% for me. It is blowback. Half the cost of Colt.

[THM7]

+1 on the RRA...a friend let me borrow his to see if it was something my 13yr old son would like to shoot in the carbine matches. The gun never skipped a beat...I believe all his mags were colt.

[Supermoto]

I have a spikes tactical 9mm. With a 7.5" barrel, its a lot of fun to shoot.

http://vimeo.com/11386623

[smokshwn]

RRA upper from Brownells. Hahn dedicated mag block, and C Products mags, 9mm compatible hammer in a DPMS Lower and it has been rock solid throughout.

[Chills1994]

fleshoid wrote:

. Then there are the Oly .223 sized mags with the block built in and no conversion or mods to your lower needed. I wouldn't have to get used to a different feel between my.223, 9mm AR and my upcoming NC .22 upper for mag changes.

Oh! Wow! I wish I had thought of that with the mags.

Extrapolating that out in the other caliber direction....just thinking out loud here....

what if you started with an AR-10 lower, and .308 sized mags, then either had special mags made or had an adapter made up where you could feed .223 out of the same mag and lower and maybe with just a barrel swap and a bolt change you could shoot .223 out of the same gun???

Or if you could pick up a kit where with the same AR-10 lower you could shoot 9mm, .223 and .308. Of course, there will be those guys who will want to shoot 6.5 Grendel and/or 6.8 SPC out of it too.

idid or does any outfit like Larue make a modular ARish upper with a quick change barrel system?

not to derail this thread...

I was looking into 9mm or other pistol caliber AR's carbines. I went to arfcom and just got totally inundated with all the choices....Hahn blocks and uzi or sten mags....then there ramped verus unramped bolt carrier groups and then special hammers and buffers you gotta use...jeesh!

all the choices and if/then's about made my head spin. at the time the Glock mag system seemed the most interesting. 33 round Glock 18 mags sound like they would be fun to shoot.

I just wanted to throw my hands up and just buy something right off the shelf that would work.

[highxj]

After researching the niner carbines, I decided on a factory Colt 6450 that I found for $1100 brand new. So far, it has been perfect with the supplied 32 round Colt mags and it's a hoot to shoot. One oddity is that it has the large trigger group pins.....I didn't notice that until I tried to stick a Wilson in it. I haven't really wrung it out for accuracy but informally it surely seems very good, and it's really light with it's skinny 16" barrel. On the down side to some may be the old style carry handle upper, but I like it for what it is.

I haven't *really* figured out what it's for yet other than a range toy, but I do like it. I may run it in a 3-gun match one time if they will let me.

Dan

[cas]

I know there are one or two guys selling DI uppers in .45ACP, and possibly other calibers (7.62x25, maybe some stuff like .357 SIG, 10mm.. not sure, I don't really remember.) Don't recall hearing about 9mm, but that doesn't mean there isn't.

I've put together two RR 9mm uppers, but oddly enough never fired a round out of either of them. I do however have an Oly .45 ACP upper. I hate Oly, I hate the Oly system with their Rube Goldberg paperclip ejector.... but you know what? The stupid thing runs and runs and runs. Round nose, truncated cone, SWC's... eats everything I've fed it, never a hiccup.

[StealthyBlagga]

If you really wanted an HK94, you could consider the ATI-imported HK-clones from Turkey. They are made in an HK-licensed plant and I hear good things about them. However, if you want a gun to win at a subgun/PCC match, you are on the right path with an AR15/9... I would go down the Colt-pattern route myself (RRA is a good solid choice).

[OPENB]

I know there are one or two guys selling DI uppers in .45ACP, and possibly other calibers (7.62x25, maybe some stuff like .357 SIG, 10mm.. not sure, I don't really remember.) Don't recall hearing about 9mm, but that doesn't mean there isn't.

I've put together two RR 9mm uppers, but oddly enough never fired a round out of either of them. I do however have an Oly .45 ACP upper. I hate Oly, I hate the Oly system with their Rube Goldberg paperclip ejector.... but you know what? The stupid thing runs and runs and runs. Round nose, truncated cone, SWC's... eats everything I've fed it, never a hiccup.

This is my point exactly, they just plain work. I'd agree about most Oly stuff, but their pistol caliber carbines work. Plus there are no mods required to the lower to switch between calibers, works with .223 hammers and buffers/springs. I had one in .45 too, it used .45 Uzi mags, which were very hard to find.

[Revopop]

Don't forget CMMG, their bolts can be used with a regular hammer, should make switching back and for on the same lower much easier.

[cas]

I had one in .45 too, it used .45 Uzi mags, which were very hard to find.

I have a grease gun mag lower. Spendy but super cool.

http://www.ny-tactical.com/Photo%20Sets/PCC2010/index.htm

Edited December 29, 2010 by cas

[OPENB]

I heard you had to use the Cavalry Arms polymer lower to use grease gun mags. Is that a regular aluminum lower? Is the mag well different to take grease guns? Very cool!

[cas]

It's a billet lower made for GG mags and the Oly system.

[Chills1994]

On some other gun forum, I saw a 9mm AR with a side charging handle. I thought that looked pretty slick!

Oh, and I read on another forum just lately that if you go with an Olympic pistol caliber upper you have to drill your lower for some paper clip pin thing which I guess acts like an ejector (shrugs shoulder).

Edited December 31, 2010 by Chills1994

[ac4wordplay]

Oh, and I read on another forum just lately that if you go with an Olympic pistol caliber upper you have to drill your lower for some paper clip pin thing which I guess acts like an ejector (shrugs shoulder).

Close, but not quite. The upper receiver is drilled and has the wire ejector installed. Surprisingly, it works quite well. Removing the ejector (easily done), the upper receiver can be re-barreled in whatever caliber you choose without issue (the holes are inconsequential).

Best,

ac

[Chills1994]

^^^ah...okay...thanks!

[sasquatch981]

I have an RRA with a spikes block and C-Products mags that have been "massaged" to be 100% reliable. It also has a Jard Trigger and hammer that breaks at 1.5lbs.

I have close to 20K rounds through it. At first I was breaking trigger pins, but once I switched to KNS anti-rotational pins, problems stopped. This has been ultra-reliable for the last 5-years. It used to have a VM-Hytech block that used un-modified uzi mags, but I wanted to switch to the "normal" mag release. Just make sure you have a "heavy-buffer" and your good to go.

Local Rifle Match Video

Edited January 3, 2011 by sasquatch981