9mm, some very basic questions (not covered in the other 9mm thread...)

[Martinjmpr]

I did read through the other thread, just wanted to make that clear. My situation is this: I want to build another AR but I already have one in 5.56, am interested in another caliber. Had thought about 7.62 x 39 because ammo is cheap, but all the stuff I read about problematic magazines made me shy away from that - I don't want to spend several hundred bucks on something that doesn't work. So now I'm thinking 9mm since I have a couple of Glocks (17 and 23 w/9mm conversion barrel.) So my questions are on the 9mm AR platform itself. First of all, does the 9mm AR use the direct gas impingement of the 5.56 version or is it straight blowback? Reason I ask is that I know other 9mm carbines are straight blowback with an unlocked bolt. Also on the other 9mm thread I was looking at pictures of the bolt and it doesn't look like that bolt rotates, but maybe I'm not looking at it right? Next question, other than a 9mm upper, what else is needed? I know there's a magazine block to take the smaller mag but is there a separate magazine release or does it use the same one as the 5.56 version? Final question, are there any "CO Legal" < 15 rd magazines that will work in these? Thanks in advance.

[MarkCO]

After I did all my research about 9mm uppers, I ended up with a .22LR upper AND a .300 BO upper. Just a thought.

[Great-Kazoo]

I did read through the other thread, just wanted to make that clear. My situation is this: I want to build another AR but I already have one in 5.56, am interested in another caliber. Had thought about 7.62 x 39 because ammo is cheap, but all the stuff I read about problematic magazines made me shy away from that - I don't want to spend several hundred bucks on something that doesn't work. So now I'm thinking 9mm since I have a couple of Glocks (17 and 23 w/9mm conversion barrel.) So my questions are on the 9mm AR platform itself. First of all, does the 9mm AR use the direct gas impingement of the 5.56 version or is it straight blowback? Reason I ask is that I know other 9mm carbines are straight blowback with an unlocked bolt. Also on the other 9mm thread I was looking at pictures of the bolt and it doesn't look like that bolt rotates, but maybe I'm not looking at it right? Next question, other than a 9mm upper, what else is needed? I know there's a magazine block to take the smaller mag but is there a separate magazine release or does it use the same one as the 5.56 version? Final question, are there any "CO Legal" < 15 rd magazines that will work in these? Thanks in advance.

NO on 15 rd 9mm AR mags. There's a smith in CT who does, or was doing mag, well adaptions to allow use of G mags. I went the sten mag / olympic upper way. At the time sten mags were $5 per.

[SAnd]

Lone Wolf R&D manufacturers AR lowers that use Glock magazines. Double Diamond shows them on their webb site but has them as "unavailable" I believe the Lone Wolf lower uses the Colt style 9mm upper. I don't believe that anyone is making a gas operated upper, they are all blowback.

http://www.lonewolfdist.com/Detail.a...285845&CAT=288

Olympic Arms is also listing a complete Glock mag carbine on theirs site-
http://www.olyarms.com/shop/rifles/a...els/k9-gl.html

It looks like both of the above will take 15 round Glock mags.

[ray1970]

Some day I plan to build a 9mm. I like the Double Diamond lowers.

[Lurch]

Straight blowback and doesn't rotate. Another option is a magwell and converted UZI mags.

[SideShow Bob]

If you wanted to go with a larger caliber, Bazooka Bros. makes pistol caliber Gas impingement ARs in the following calibers.

45 ACP, 45 Super, 460 Rowlands, 10 mm, 7.62x25 and 45win. Mag.
And they sell complete upper, complete lowers or stripped lowers for the same calibers.

http://bazookabrothers.com/pages/home/1

[ChunkyMonkey]

GMR
http://www.jprifles.com/1.2.13_GMR.php

Or the low end one is JR 9mm carbine

[Circuits]

The most common 9mm upper systems, Colt pattern or Olympic pattern, are blowback, with no gas system at all.

There are direct impingement 9mm uppers, but they can be a bit ammo picky and problematic, given how little gas the 9mm cartridge generates. The 45 and 40 DI versions are much more reliable and less ammo-dependent.

No matter the upper you choose, in order to use Glock mags, you'll need a mag block or a dedicated Glock mag lower. The mag blocks are no longer made or generally commercially available so far as I know, so getting one involves finding one used or commissioning custom work.

[ThunderSquirrel]

I have a Double Diamond Lower that takes Colt Mags, paired with a Rock River 9mm Upper. I went with the dedicated 9 upper only because it does not have the hole drilled for the gas tube. Its not a huge deal, but keeps the blowback from throwing out into the handguard / barrel. Just a preference thing.

As stated above, using Glock mags is going to require a dedicated glock lower. Double Diamond makes a great one, But I think their lead times are crazy now. Also, glock mags will also require you to 'fit' your bolt to the mags. The feed lips on a glock mag are higher than they are on a colt mag, and require you to take some material off your bolt to avoid excessive wear.

If you're interested in taking a look at one and ideas, I can meet you up at Bowers sometime, since it says you are located in Englewood.

Obligatory gun porn below...