9mm AR

[tomme boy]

Anyone build one or buy one. I just ordered a pistol lower that uses Glock mags from PSA. I already have a bunch of Glocks so it seems to work to stay with the same platform.

Next I have to figure out which upper to get. I think I am going with the FM Products 9.25" side charger upper or PSA 10.5"

Just wondering how picky they are? If they are like the pistols to get to shoot well?

[BNE]

I assembled one for a friend a few weeks ago. I have not shot it, but he loves it. Said it was picky with reloads, but did fine with factory. (I think reloads will work fine, just need to size the cartridge correctly. )

I have one on order now! I am going with the FM products one that uses Glock mags and holds a spare mag in the handle. The “Glock store” says they have them in stock, but I don’t have a delivery date yet.

I went with the FM products 8.5” barrel as I hope to get into suppressors when I do t have a college bill for my daughter!

Can’t wait to compare notes!

[Papercidal]

I have a psa 10.5" upper and it works great other than that the chamber leade is pretty short it works perfectly with fmj or longer thin round nose (bayou 124gr rn) but truncated cone style bullets have a tendency to stick in the chamber if they aren't loaded pretty short.

[sukivel]

I’m interested in this...any reason, other than length, to not go with a longer 16” barrel?


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[Ickisrulz]

I’m interested in this...any reason, other than length, to not go with a longer 16” barrel?


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Once you get to 9 or 10 inches in a 9mm, you just aren't going to get much more velocity by going to a longer barrel. Of course anything under 16 inches is going to either be a pistol or a SBR. So if you don't want a pistol or SBR you'll have to go 16 inches.

http://www.ballisticsbytheinch.com/9luger.html

[dragon813gt]

I built one w/ Stern Defense parts so the lower wasn’t dedicated. I have no issue w/ the mag release location which seems to be an issue for some. I can take the mag block out and run any upper I want on it.

I don’t recommend the KAK Blade pistol brace. It beats you up good if you do shoulder it. There are more comfortable options for the occasional shouldering. And as of typing this shouldering a pistol brace is legal.

Mine has been reliable w/ any ammo I’ve fed it from WWB 115 grain to 155 grain cast. The throat is generous on the barrel and like all 9mm it’s important. It’s one of the most fun guns I own.

https://farm2.staticflickr.com/1740/27548151567_357690b890_b.jpg

[tomme boy]

I definitely want to keep it at the 8-10" area. The short throat is what I am worried about. I do have a bunch of lapping bullets but I don't want to use them unless I have to.

[merlin101]

I built a 9mm, I had the standard lower and used the Mean Arms 9mm mag inserts and a cheap no name barrel I picked up at a gun show. When I got the bbl home I noticed that it had no feed ramp, I mean absolutely NONE that I can see, I put it together as is and am happy with it. It seems to handle anything brass case even cast reloads without a problem, the only rounds that do hang up are some cheap steel case stuff I picked up a while back and didn't realize it was steel. That stuff is ROUGH and doesn't work well in any of my 9s, it's only redeeming feature is for malfunction drills. BTW I used the heavy BCG from Brownells and a heavy buffer as was recommended to my and it wooks.

[Shingle]

9mm carbines are weird about bullet and powder selection. The fastest load i have used is out of a 13.5" barrel it gets 165fps faster than a 16" with 124gr. over cfe pistol powder. Anything under 10.5 is slow.

[tomme boy]

Don't care about speed. Just want reliable and cheep. Consolidating my reloading is the reason for this. And I have always wanted a pistol caliber AR. And now that they are actually cheap enough and they are making them easy to use with Glock mags, why NOT?????

Plus this may be the last time we are able to own something like this ever again. So I am focusing on things I want right now over this coming year. After this year is up things are going to get mighty scary again and I am NOT going to pay stupid prices for anything. Did not last time and will not next time.

[Tackleberry41]

I put one together on an 80% dedicated lower, colt style. Yea the stupid 16in barrel but makes it legal. Not tried a comparison of the various lengths, but 16in they are alot faster than an 8in barrel.

One issue I had and seems common is some do not cut any sort of throat. Barrel from midway, it would load and fire, but near impossible to unload with the bullet jammed in the rifling. A second barrel from another company was the same. So required buying a throating tool.

Not seen any issues w reloads vs factory. Fun to shoot.

[m.chalmers]

With a Glock style lower most uppers will run fine. BUT any bolt must have the "Glock" style mod. An unmodded Colt bolt won't work.

A cheap PSA upper will work fine.

[Cosmic_Charlie]

With a Glock style lower most uppers will run fine. BUT any bolt must have the "Glock" style mod. An unmodded Colt bolt won't work.

A cheap PSA upper will work fine.

The FM Products complete Colt style 9mm uppers work fine with their Glock lowers.

[m.chalmers]

The FM Products complete Colt style 9mm uppers work fine with their Glock lowers.

Bolt is modded.

[Gtek]

BUT any bolt must have the "Glock" style mod? Would anyone be so kind as to save me the googlefoo time?

[Lloyd Smale]

ive got a 16 in cmmg that is as reliable as any gun ive ever owned. It uses colt mags and eats anything. I also have 4.5 inch gun I built on a psa glock lower and an upper from another company whos name I forgot because there was a rush on at the time and I just couldn't get an upper from psa. It was more of a learning experience. Mostly with finding the buffer and spring that worked best in it. I ended up with a 5.5 oz buffer and a carbine spring in a pistol tube. It also took some slight grinding on the barrel to make a sort of feed ramp. It now runs great with glock mags or the clear mags psa sells. With any of the glock knock off mags its still troublesome. theres a company that sells a ramped barrel and a bolt that matches it. If I did it again I would surely do it that way. I even bought a what they call upgraded bolt from the company that sold me the upper. It came rough with sharp edges and need quite a bit of smoothening with a file and stone. It also had the ejector pin whole to big and I kept breaking extactors or would find all of a sudden the gun wasn't ejecting right and would look and the ejector was GONE. I found a slightly larger pin at the parts store and used red Loctite on it and it never acted up again. But bottom line that bolt was FAR from an upgrade. Either that or the stock one was a piece of broom handle. took me most of the summer but it now runs well. If I had to do it today use the ramped barrel do some reaserch on which is actually a good bolt and id probably go with a colt mag psa lower. Mags are much cheaper and like I said my cmmg gun doesn't miss a beat and another downside to the glock lowers is they don't have last round bolt hold open and the colt mag ones do. All that said I highly recommend a 9mm ar. Nothing so much fun is so cheap to shoot. My cmmg gun will shoot cast coated bullet under 2inches at a 100 yards!! 4.5 inch gun does about the same at 50. Did I tell you that 4.5 gun is cuter then a puppy. Better get them while you can because it looks like pistol registered ar15s are pretty high up on the liberals banning agenda.

[Lloyd Smale]

ive got a 16 in cmmg that is as reliable as any gun ive ever owned. It uses colt mags and eats anything. I also have 4.5 inch gun I built on a psa glock lower and an upper from another company whos name I forgot because there was a rush on at the time and I just couldn't get an upper from psa. It was more of a learning experience. Mostly with finding the buffer and spring that worked best in it. I ended up with a 5.5 oz buffer and a carbine spring in a pistol tube. It also took some slight grinding on the barrel to make a sort of feed ramp. It now runs great with glock mags or the clear mags psa sells. With any of the glock knock off mags its still troublesome. theres a company that sells a ramped barrel and a bolt that matches it. If I did it again I would surely do it that way. I even bought a what they call upgraded bolt from the company that sold me the upper. It came rough with sharp edges and need quite a bit of smoothening with a file and stone. It also had the ejector pin whole to big and I kept breaking extactors or would find all of a sudden the gun wasn't ejecting right and would look and the ejector was GONE. I found a slightly larger pin at the parts store and used red Loctite on it and it never acted up again. But bottom line that bolt was FAR from an upgrade. Either that or the stock one was a piece of broom handle. took me most of the summer but it now runs well. If I had to do it today use the ramped barrel do some reaserch on which is actually a good bolt and id probably go with a colt mag psa lower. Mags are much cheaper and like I said my cmmg gun doesn't miss a beat and another downside to the glock lowers is they don't have last round bolt hold open and the colt mag ones do. All that said I highly recommend a 9mm ar. Nothing so much fun is so cheap to shoot. My cmmg gun will shoot cast coated bullet under 2inches at a 100 yards!! 4.5 inch gun does about the same at 50. Did I tell you that 4.5 gun is cuter then a puppy.

[Cosmic_Charlie]

I am running an FM Products hybrid Glock lower with one of their 9.5" Colt style uppers. Has functioned 100% so far. I also have an FM billet Glock lower that I'm deciding on an upper for. Would have gone with a .45 acp Glock lower if I had been able to find one in stock that had the lrbho feature.

Need to run some rounds over the crono and see how fast we are. Got FM's premium trigger to install as well.

[dragon813gt]

There are Glock lowers, and mag blocks, w/ last round bolt hold open. Just make sure you know what you’re buying. I believe the PSA lower is non bolt hold open. I know for certain that the Stern Defense mag block has last round bolt hold open. It’s a feature that will eventually be on every one since people want it.

There’s a lot to be said for certain systems that don’t require any fiddling w/ buffers, springs and other parts. I can remove the Stern Defense mag block and run any upper w/out changing out any parts. I am running a heavy buffer but this doesn’t effect the operation of any of the other uppers I own.

Regardless of what you buy and build. They’re an extremely fun gun to shoot. Ripping tough a 33 round 9mm mag is a lot easier on the wallet then a 30 round mag full of 5.56.

[tomme boy]

I really don't care about the last round hold open. I shot so many AK's and 10/22's that it does not even bother me.

I am hearing of some barrels that are having NO throat. Anyone run into this? I want to run the Lee 120 TC bullet. That seems to run in every other 9mm I have ever had.

[Shingle]

The 9mm AR will drive you nuts half or more of the barrels have no throat. I have 5 different barrels 3 would not chamber anything but 115gr. round nose. I got a clymer chamber reamer all now are way more accurate and will chamber up to 160gr. of any flavor and they are way more reliable.

[tomme boy]

Well I talked to a few people last night and this AM. And found out that most of the barrels seem to be all treated with melonite and will not be able to be reamed. Already talked to someone that ruined a couple reamers trying to ream some throats. The melonite is harder than hard chrome.

I also sent FM Products a email and asked them about shooting cast bullets in their uppers. They kind of beat around the bush about cast. But said they have thousands of uppers out there that people reload for and have had no reports of anyone having problems with cast in their barrels yet. But that they would really like to hear back from me what I find out if I do choose their upper as they have no knowledge of cast in them.

One thing I have seen about FM Products is they will stand behind their uppers 100% no matter what the issue is. Even if the issue was caused by the customer. Problem is no one has what I want in stock right now.

[dragon813gt]

Stern Defense barrels have generous throats.
https://getstern.com/barrels/barrels-9mm/

[Cosmic_Charlie]

Uncle Jim shoots cast through his FM 9mm AR and gets nice groups too!
https://m.youtube.com/watch?v=XdYdxd_iYOk

Primary Arms has good prices on their uppers.
https://www.primaryarms.com/Brand+Foxtrot-Mike-Products

Brownell's has their lowers in stock. The last round bolt hold open set up works very well on both mine.
https://www.brownells.com/manufacturers/fm+products+inc/index.htm

[Cosmic_Charlie]

Well, prices went up substantially at Primary Arms. Still reasonable IMHO when you look at the costs of building your own complete upper from parts. Ordered a 5" upper from them today for the hybrid lower. Should be a very light and handy unit.

[dragon813gt]

I was upset that Primary Arms is now charging tax. I know it’s coming to everyone. But I will look at other sites that still aren’t charging it. I’m riding that one until you can’t anymore [emoji23]

[tomme boy]

I seen that. I was going to place my order this Friday. I am calling them. They closed my account for some reason. They had a 25$ credit on there from a past order. I have not ordered anything from them in a couple years. They probably figured I forgot about it. Well I didn't! They screwed up my order the last time. I took the credit and kept the wrong product they sent me.

If not I will go with the PSA upper. PA is getting too big. They used to be a one man shop when I first ordered from them YEARS ago.

Pretty much everyone is charging tax now. It depends on the state you live in on whether they charge it or not. If you live in a Dem state then bet on it you are getting charged.

[HotGuns]

I build all sorts of 9mm AR's. Here's a little PDW I built. It is a registered short barreled rifle due to the stock. This one used the Colt style 32 round mags.

235357

[Iron369]

My glock 9mm sbr. https://uploads.tapatalk-cdn.com/20190207/63e3b9627c74be3c7e3271d76eadc390.jpg

[Cosmic_Charlie]

very nice!

[Warhawk]

I built a Foxtrot Mike (FM Products) 9mm carbine. Mine is 16" and takes Glock magazines. Despite the warning from FM that Winchester White Box would cause problems, I tried some. At 50 yards it was putting everything inside a 2 inch circle. I've also shot a variety of other ammo, and nothing shoots as well as the WWB. I did have some failures to feed using Israeli IAI die cut hollow points. They would apparently hang up on the chamber mount. This ammo has a very sharp jagged edge to the hollow point. Not a big deal to avoid that ammo.

[kbstenberg]

I am concerned that if there is a party change in the next election. They will not just make laws on new pistol cal. AR's. They will go for broke and try a total confiscation.

[Cosmic_Charlie]

I am concerned that if there is a party change in the next election. They will not just make laws on new pistol cal. AR's. They will go for broke and try a total confiscation.

Confiscation? Messy business that.

[Cosmic_Charlie]

I built a Foxtrot Mike (FM Products) 9mm carbine. Mine is 16" and takes Glock magazines. Despite the warning from FM that Winchester White Box would cause problems, I tried some. At 50 yards it was putting everything inside a 2 inch circle. I've also shot a variety of other ammo, and nothing shoots as well as the WWB. I did have some failures to feed using Israeli IAI die cut hollow points. They would apparently hang up on the chamber mount. This ammo has a very sharp jagged edge to the hollow point. Not a big deal to avoid that ammo.

I have been using CCI Blazer 115 gr. and it is very accurate. Tried some Aguilla hollow points and they would not feed. Remington +p HTP 115 gr. feeds fine. It has a rounded tip into the hollow point.

[Lloyd Smale]

I bought a 4.5 inch psa and it never ran well. What I ended up with is what I should have started with. I replaced my barrel with a faxom because they have a much better feed ramp (there on sale right now on there web site for around 80 bucks) and installed a https://taccom3g.com/product/taccom-glock-lower-feedramp/ which did wonders for feeding cast. Add to that to use AT LEAST a 5.5 once buffer, loose the pistol spring a carbine recoil spring (some say even an ar10 spring) and never go to a light hammer spring. If anything replace the stock one with an extra heavy wolf. I thought I might have a chamber problem too but what was happening is softer bullets were getting damaged so badly when feeding that they wouldn't allways chamber. If you do NOTHING else spend the 3o bucks on that feed ramp. Seated to max overall length in the loading books it feeds everything
The 9mm AR will drive you nuts half or more of the barrels have no throat. I have 5 different barrels 3 would not chamber anything but 115gr. round nose. I got a clymer chamber reamer all now are way more accurate and will chamber up to 160gr. of any flavor and they are way more reliable.

[Moleman-]

Usually just make my own 9mm AR barrels but bought a AR-Stoner barrel as a gift for my FIL a while back. He came over, we put it together and went in the back yard to test it. It fed terribly. I just copied the feed ramp on a MKII sten barrel for the feed ramp on the barrels I've made, so we took his barrel off which had a much smaller feed ramp and changed the angle to make it wider not deeper and radiused the transition from bevel to chamber wall slightly to remove the sharp edge. Worked great after that.

[Baltimoreed]

238950
All my pcc’s are in .45 acp and use greasegun mags so I can’t help you but good luck on your build. Pcc’s are a hoot and can be used in ipsc and zsa matches nowadays. Fun with a gun.

[tomme boy]

I went with the 8" barrel from PSA. It has fed everything I have tried in it so far. I have tried the clear 31rd mags, the 27rd Magpul mags, g19 mags, g26 mags. and they all fed Lee 124TC bullets and MP359-125 HP, RMR124 plated. Federal 124gr HP

Only misfeeds I have had was when I went to low on the charge weights to find how low I could go. It does have a short throat but not any shorter than my gen4 g19 does.

[Loudenboomer]

I bought a Stern Defense 4"upper and Fox trot Mike Lower. Feeds Bayou Bullets cast 124 TC and 124 FMJ. So far so good but just getting broke in. It will be even more fun when it's can gets out of Jail! :)