9mm AR in MA questions

[Cur]

So I want to build a 9mm AR... as always, living in MA complicates this, and "just move" sadly isn't a viable solution right now.

I do have a "pre ban" lower, so I have that going for me.

It's a mil-spec buffer tube, if that info is needed or relevant.

Uzi pre-bans seem to be readily available and cheap enough that I can buy 5-6 of them without breaking the bank as opposed to the Colt pre-bans people want arm and legs for. Modifying them isn't a big deal, I "know a guy" who can do machine work, and I own a dremel.

I was looking at this mag well insert by Hahn. (I don't care about losing last round bolt hold open). Seems to get a lot of positive reviews with modified Uzi mags.

I've looked at CMMG and RRA complete 9mm uppers.... at this point, are they just a universal fitment in regards to feeding from Uzi mags? Pick the barrel length / material / etc and I'm done?

Do I need a different spring or buffer?

I feel like I'm missing something...

Thanks~

 

[Rob Boudrie]

1. Yes, you need a different spring and buffer. I recommend the JP one. wwww.jprifles.com.

2. I have no experience with Hahn mag block. I have a Rock River block and can highty recommend it. It requires no receiver modification, and loads from the bottom, using a really nice allen screw driven retention mechanism. The Hahn loads from the top and they brag it cannot fall out. I don't believe the Rock River presents any fallout problems either (even if the lock was loose, the mag catch would keep it in). I like the way the RR locks in without any play, and uses shafts that push against the receiver without any twisting (you are not driving a screw against the receiver).

How about if you get a Hahn and we meet to compare?

3. I recommend a Nissin for cutting the mag catch and lowering the rear notch (日新工機｜立形多面加工機(５軸制御マシニングセンタ)), but a local shooter did his with a dremel and his works flawlessly. Or, you can buy in-stock mags from Greg at GFA and he can cut the notches.

4. If you want to go de-luxe on the 9x19 upper go with a JP. If you find a day about 50deg without rain, PM me and you can meet me and Hopkington for some fun times (bring ammo) and you can check out the JP. Put the JP next to any of the modestly priced uppers and you will understand that thou gettuth what thou payuth for.

5. UZI mags are fine as long as you don't get your panties in a wad over the no bolt holdback. I suggest an extension and longer spring from Taylor Freelance (www.taylorfreelance.com) to bring the 32 round UZI mags up to 42 rounds.

6. www.robertrg.com is a great source for UZI mags - cheap, great assortment of vintages and quality levels (ie, degree of rustedness if any). I found his description of condition to be right on and service prompt and reliable.

 

[413guy]

hahn also makes a bottom load block. just picked one up on sale for 150 shipped. I have a dedicated top loader as well I got for 200 last year, but like the idea of changing calibers faster with the bottom loader, just release the pressure hex pin, rather than have to remove the bolt catch.

I did a lot of reading on them both, people are all over the place with their feelings in regards to top and bottom load differences. some say the screw against the receiver in the bottom loaders causes outward pressure inside the magwell that can be bad and cause splits, but I can't vouch for that nor have I ever seen it. not having to remove the bolt catch like with the dedicated top loader is something to think about though.

you can find pre ban mags other than uzi, but takes time and are considerably more expensive. Uzi mags work well, I have some modified uzi and some old metalforms. I did my uzi mags with a dremel and small 8inch drill press. did 5 or 6 and each one came out better than the next, and they all work. BHO is just nice with the metal forms sometimes.


rob, if you ever want to compare the 3, let me know.


and cur, if you're interested in a line on the hahn blocks for 150, the guy may have some left, pm me and I can let you know

 

[Rob Boudrie]

you can find pre ban mags other than uzi, but takes time and are considerably more expensive.

Depends on how far a drive you are from downtown Natick. GFA has pre-ban UZI and Colt mags in stock.

 

[Cur]

Thanks for the info guys. I priced out a complete JPR upper and it's only about $200 ($900) more than a CMMG, so I might lean that way. I've used JPR stuff before, and it is top notch, and I'm a big fan of "buy once, cry once" philosophy.
I'll definitely check out GFA for mags when the time comes, thanks for the tip. I'm up by Lowell, so no issues making a Sat trip down that way.

So if I order the full JPR upper, I'll still need their buffer and spring, and either the RRA or Hahn mag well adapter... then mags, then I'm good to go?

 

[Rob Boudrie]

You can use any 9mm buffer and spring with the JP upper, however, the JP one is really nice and doesn't go "twang". They have two varieties - one is reputedly more comfortable; the other better for fast competition shooting. Call the factory and talk to Dustin if you are ready to buy and have questions.

If the JP premium is only $200 for the upper, you will probably regret it if you go cheap.

The only thing that seems to be missing in your specification is a sighting system. JP himself recommends the Vortex Spirtfire 1x.

If you plan on buying converted UZI mags from GFA, call ahead. Greg has a lot of stuff piled up on his Bridgeport in the back room and is not equipped to notch mags while you wait.

 

[Cur]

You can use any 9mm buffer and spring with the JP upper, however, the JP one is really nice and doesn't go "twang". They have two varieties - one is reputedly more comfortable; the other better for fast competition shooting. Call the factory and talk to Dustin if you are ready to buy and have questions.

If the JP premium is only $200 for the upper, you will probably regret it if you go cheap.

The only thing that seems to be missing in your specification is a sighting system. JP himself recommends the Vortex Spirtfire 1x.

If you plan on buying converted UZI mags from GFA, call ahead. Greg has a lot of stuff piled up on his Bridgeport in the back room and is not equipped to notch mags while you wait.

Ok, good info. I'm waiting for tax return $$ but I'll call first. I have a spare red dot, and some irons laying around so I'll probably use those for the time being.

 

[Cur]

You can use any 9mm buffer and spring with the JP upper, however, the JP one is really nice and doesn't go "twang". They have two varieties - one is reputedly more comfortable; the other better for fast competition shooting. Call the factory and talk to Dustin if you are ready to buy and have questions.

Ended up talking to James for about 30 minutes. Put my order in yesterday... 6-8 weeks!!

I went with their silent captured spring, mostly because it's just one piece and I like the engineering thought behind it. I'll give Greg a call in a couple weeks and talk to him about some mags, probably pick up half a dozen of them. Any idea (roughly/ballpark) what he's asking for modded 32 rounders?

 

[Rob Boudrie]

Please post a review of the JP when you get it. I expect you will be quite happy having spent the extra.

No idea on Greg's price. I'll talk to him about a group buy to make it worthwhile setting up his Bridgeport.

RTG Parts - Gun Parts and Militaria - RTG Parts, LLC is the standard for low cost UZI mags, but he does not do mods. The only pre ban 32 rounders he has now are "with rust". Gregs are going to be in better shape, but probably cost more like $20 than $10, plus mod fee.

 

[Rob Boudrie]

I've noticed that all the on-line suppliers seem to be out of 32 round pre-ban UZI mags, with the exception of some lower priced rusty mags.

25 rounders are still plentiful.

If you are interested in a 9mm EBR, you may want to stock up on mags while the supply line remains open.

 

[MGnoob]

Depending on which grade you get from RTG its a killer deal. They used to be even cheaper... they have a "gunsmithing special" and "value packs"
The uzi mags very well may come in perfect...with the steel hk91 mags like 4 out of 50 might have a meaningful amout of rust, but could be cleaned in no time.stay away from the lowest grade, your asking to be unhappy.

I was a huge fan of the colt mags for ar15 9mm...now i think it would be a mistake not to use cheap uzi mags

50 pack uzi mags


The top 4 mags look alot worse then they are in real life. The rest are near perfect, and come individually plastic wrap.. i could have "saved" $100 and received 50 rusted crap.

Both these mags have nice chrome followers

 

[Rob Boudrie]

Depending on which grade you get from RTG its a killer deal.

I got a few of the pre-ban top condition 32 rounders from RTG - very easy people to deal with. All RTG has left now in 32 rounders is the rusted ones. I may get a few and see what bead blasting plus refinishing does for them.

Any idea (roughly/ballpark) what he's asking for modded 32 rounders?

$45 for modified UZI mags when he has them in stock (he is looking for more inventory now); about $100 for the Colt mags.

 

[MGnoob]

That box of uzi mags in the photo is an order of the "rusty" ones is from RTG no more than 1 week ago...
They aren't rusty as far as im concern.they are IMI mags so they are all preban and for how cheap IMI mags are getting anything else seems silly.

Some of the hk 91s mags could definitely use refinishing, but the are datestamped 1963..so for 55 years old they arent that bad.