9mm AR setup

[greyling22]

I am looking hard at converting an AR in 223 that I don't use into a 9mm carbine. If I can do it cheap enough.
Currently I load a 125grn lee rnfp made a wheel weights over 4grn of WSF. bullet is sized .358 and runs about 950-970fps out of my handgun.

I'd like to keep that load, but it is my understanding that 9mm AR's want a relatively hot load to run right, and my load is not hot.

So, here are my questions:
Can I run a lighter spring and get proper function like I had to with my light blackout loads? I know the AR is blowback, not gas operated.
Would a lighter or heavier buffer help ensure that the gun would function?

I have a spare carbine spring that I can cut short for experimental purposes, and I have a spikes st-t2 buffer (4 to 4.3oz according to the website) barrel would be 16", no suppresor.

and finally, I have not shot an ar9 before. I hear if you are running suppressed you get a lot of gas in the face. what if you are not? I shoot left handed.

[Moleman-]

Blowback works by bolt and buffer weight (mass), the spring just needs to be strong enough to reliably strip a round and chamber it. I use the Lee 124gr rn-tl with W231, greendot, or unique in mine at just a bit faster than what you're pushing them. I've shot mine suppressed and it does allow more gas to blow back towards the shooter than without the suppressor. Never shot them lefty though. Put all of mine together from parts. You'll need a ramped bolt, mag, magwell block, muzzle attachment and barrel bare minimum along with your 223 rifle. I'd likely also get a 9mm port door and deflector since you shoot left handed. Jse has 9mm port door kits for around $12-$13. The cheapest best bolt I've found recently is the blem Spinta precision for $110. Jse often has barrels for $100-$130. I would likely also get a longer heavy buffer. Some people put several quarters under the recoil spring in the buffer tube to limit bolt movement instead of the longer 9mm buffer. What magazine are you going to use?

[greyling22]

Thanks for the info. I wanted to make sure I could use my ammo before I got too into the details of picking out specific parts.
Probably I should have started with deciding if I want Colt or Glock mags. I don't have a glock, so I'd be starting from scratch mag wise. I've heard too many sketchy things about the promag block, so I was eyeballing the kak block that takes Colt mags(100), or the upcoming torkmag block that takes Glock mags. ($75)
Or I could spend a little more and get a dedicated glock lower from runner runner Guns or goballistic for around 140 delivered and ffl'd. So affordable options either way.
Palmetto has some good deals on Colt style metal form mags if I go that route, and glock mags are everywhere.
I figure glock is the future, and the mags are supposedly easier to load, but the Colt gives you last round hold open and looks better, so I don't know.

[cwheel]

I just finished putting together a 9mm AR with PSA parts. I got the lower that uses Glock mags, no last shot hold open. Mine shoots lite cast reloads quite well shooting a 120 gr. Lyman 358242 over 4.7 gr. of Unique. That bullet and powder charge was developed to use in a Ruger LC-9 to train my grandson, a lite load. Still functions well in my PSA 9mm AR. I don't think you will have much of a problem needing rounds loaded to the top of the chart in a 9mm AR, but that depends on how you do your build and what parts you use. I think I paid $250 for the fully assembled lower and another $350 for the fully assembled upper with bolt and charging handle, $600 for the rifle without sights. A Colt 9mm around here runs about $1200, and putting one together from parts ran just about as much by the time you were done. What motivated me to build a 9mm AR was the price of 22 LR. I have a Dillon 550 setup and run 9mm cast rounds through at about 4-5 cents a shot + some labor on a snowy day. 22 LR around here was running around 8-10 cents a shot. Wouldn't take long to pay for that 9mm AR at that rate when the grandkids show up.
Chris

[Moleman-]

I had about 25 sten mags when making my first 9mm upper so that's what I used 7-8 years ago. If I had it to do again I'd likely go with the colt mags and a dedicated lower. I've been eyeing dedicated colt style lowers lately. If going with the colt style with a bolt hold open feature, the longer buffer or block (quarter stack) will limit how fast the bolt is traveling when it is stopped by the bolt latch. Often guns that use a standard length car buffer without the block will break or bend the bolt latch. Just recently finished another one because the kids were burning through my 223/5.56 ammo for plinking. Cast lead 9mm's are more economical than 223 and lets the kids feel like they're shooting something bigger than a 22lr.

The last batch I loaded up was for use with a suppressor. 147gr berry's over 3.6gr W231. The 124gr Lee RNTL with 4.0gr W231 is supersonic out of a 16" barrel but cycles well in my blowback 9mm ar's.

[Jack Stanley]

By the time I finished converting my .223 type lower , it would have been as cheap to buy a dedicated lower and use that . I chose to use Colt style mags because a Glock is not very likely in my future . And , as mentioned PSA has good deals on them from time to time plus having a bolt hold open is a good feature .

Mine is not suppressed and I shoot left handed and I've never had any problems .

Jack

[greyling22]

well, right now I'm looking at a dedicated glock lower from new frontier (rebranded. probably runner runner or joebob), a spinta blem bolt, and trying my carbine spring and st-t2 buffer, with the understanding that I will probably need an H3 buffer in the end. I already have a 16" faxon barrel and the upper, handguard, and lower parts from the 223 AR. I just need a good muzzle device. hoping for just a nitride finished thread protector. need something to cover .58 length of threads and an OD of .728. but I may need a crush washer and flash hider if I can't find something that fits. (open to suggestions)

[milsurpcollector1970]

I built one from an 80% lower colt mag style ran good didn't like the gas in the face (not suppressed) Also recoil was kind of annoying not painful though. I was running a max load of power pistol with 115 gr jacketed getting around 1400 fps

I think the spring and buffer can be taylored to any load u want

[Tmaloy]

My AR9 pistol build uses the Colt style. I used the Lee 120 TC under 4.5 grns of CSB1 powder and the Lee 150 RN under 3.5 grns. of HP38 for a softer shooting load. Cycles a bit harsh with the Lee 120. I also invested in a Hahn block and Hahn heavy buffer that is longer than a regular buffer. If you plan to use a carbine buffer tube, you can use a standard length buffer but if you do that I suggest putting a $1.75 in quarters to use as a spacer in the bottom of the tube. Learned that this was the reason some people were breaking bolt catches when it comes back to far and jams into the bolt catch.

[CITYREPO61]

I built a 9 AR with a 223 lower, Brownell parts with a JSE complete uppEr. I run 124 lrnfp in front of unique.
Awsome fun.
Whatever platform you go with will be fun to shoot.

[77aspen]

greyling22
I built a 9mm 80% colt style lower recently. I found that switching from a H2 AR style buffer and stock carbine spring to a Wolfe XP carbine spring and dedicated 9mm style buffer changed the whole recoil. It went from sharp kick feeling to more of a push. I am also a lefty, with the ar buffer I could feel some unburnt power and blow back. With the dedicated 9mm buffer it is definatly less to almost gone.

Just an FYI the H3 buffers weight 5.4oz and the 9mm buffers are 7.5oz to 10oz. I skipped the H3 after doing some reading on the 9mm buffer, since mine is dedicated and I wasn't sure the H3 would be a big enough jump in weight.

I load the Lee 120TC nonTL over BE at about the same speed as you for my Glock and AR. I works with the new xp spring and 9mm buffer.

The 9mm platform is fun when it works right but it can be a pain to get there. I had to bend and the file the ejector, kept geting stove pipe jams, and you want a 9mm hammer or rounded hammer.

Hope this is helpful.

[azgunner]

Go for a brand new dedicated 9mm and forget about converting your existing AR. There are some amazing deals on PSA and with the specialty parts you'll need, it just isn't worth it in the end. Back before PSA made them, I bought a dedicated CMMG colt style lower for $150 - stripped, but the YHM magwell blocks were going for $175, so it only made sense. These days you can get some crazy deals and build yourself a PSA 9mm glock mag carbine for under $500 if you grab those deals.

[HankBoman]

Don't know if you've finished or even started your build yet but here's my .02.

I built mine from an 80% New Frontier Glock mag lower. I also used the New Frontier bolt which allowed me to use a standard lower parts kit. I really wasn't too concerned about LRBO so I just used a standard mil spec upper. I went with a Kaw Valley 8.5" barrel and a Kaw Valley linear comp.

It's a lot of fun to shoot and I've put a few thousand rounds through it so far. The lack of a LRBO still doesn't bother me but if it ever does, there are a few uppers out there that address the issue. The one I have my eye on for the price to come down on is a non reciprocating side charger which would be pretty cool. Until then I'll just keep emptying 30 rd Glock mags until it doesn't go bang and slap in another mag. No big deal.

[Shingle]

Iv got 5 carbines that load would run great in carbines tend to work with lighter loads than handguns unless you over buffer it there is little need for buffers above 5 oz. in a 9mm IMHO.

[Moleman-]

Make my own 9mm buffers out of 304 SS and they usually come out at around 7.8 ounces. Shooting them suppressed and you'll get a lot more gas coming out the ejection port and charging handle area with a 5.5 ounce buffer.

[greyling22]

I went ahead and built on a palmetto Glock lower with a Midway 9mm buffer ~5oz a faxon 8" barrel and a regular carbine spring. It cycled great with my 4 grn of wsf and a Lee 125grn lrn bullet, but I had a couple feeding problems early on. The angle of the bullet moving from the mag to the chamber would deform the bullet some and occasionally hang up with the bullet jammed in the top of the chamber.
I found a cz Evo scorpion carbine locally for cheap and tried that. Runs like a top, bullets are fed straight into the chamber, and accuracy is good. Less crud back at my left handed face too.
Now, it had the worst trigger I have ever pulled, the safety was too stiff and the grip sucked. But I was able to fix all those issues. I kept the cz and sold the ar.

[Moleman-]

Ended up getting a couple CMMG lowers when they were on sale a while ago and passed the magwell colt style magazine block onto my father inlaw. The dedicated lowers feed much better. I made my own barrels with a 33 degree feed ramp and have no issues with the Lee 124gr. Got an AR-Stoner 9mm barrel to go with the magwell blocks and found it didn't feed as nice even in my CMMG 9mmm lowers so we're going to recut the chamber bevel to 33 degrees and see if that fixes it. Still use the sten mags and magwell blocks for the DI uppers since they don't need the fixed ejector.

[747 captain]

I use lee 125 gr. Do get a bit of leading though