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AR-9's - Teach Me

mu2bdriver

mu2bdriver

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Thinking about them. Who makes quality parts? Are there general issues with them? Is one ammo weight better than the other? What are your firsthand experiences with them?
Thanks in advance.
 
Most AR-9s are straight blow back designs, so they are much more picky with their buffer spring/buffer combinations than a regular AR. They are dependent on the bolt mass plus the buffer weight and spring to hold the bolt closed long enough to let the pressure drop to safe levels, yet not be so strong that they prevent the gun from cycling. CMMG does make a radial delayed blowback 9mm (upper only and full rifle), that I would think would be a bit less picky, but I don’t have any first hand experience with them. To avoid having to pick out my own buffer spring/buffer, I went with an FM products complete build kit (no longer available) that included their matched buffer spring/buffer. Just needed to add my own 9mm lower.

The FM parts were all high quality and I haven’t experienced any problems with them. The AR-9 I built using a 80% AR-9 lower works just fine with a standard AR fire control group. Of course I don’t put a lot of rounds through it since it was just a “for the heck of it” build.

Most AR-9s lack a last round bolt hold open since there is no standard for it. The manufactures that offer it generally require you to use matched uppers and lowers from the same manufacture, since the LRBHO design is specific to them.

All in all, if I wasn’t just building an AR-9 for fun I’d stick with a 9mm PCC. The Ruger is good bang for the buck, plus it can use Glock magazines (good if you’re a MA inmate that needs to use pre-bans). I like my Beretta CX4, a bit more expensive than the Ruger, not a take down and some find the design off-putting. The Sig MPX is much more soft shooting than the blowback designs, being a gas operated short stroke piston, but is way more expensive.
 
JP Rifles if you're going to use Glock mags. Buy once, cry once.

If you manage to find a Colt SMG pattern lower you can use notched Uzi mags (or Colt SMG mags $$$$). I would still suggest a JP Rifles upper.
 
ok, i will say that.
9mm luger has very little practical sense in a rifle. it was an oddity build while the 9mm ammo was dirt cheap, to get it done for fun and play at the range.
now as 9mm ammo is on par with .223 - it is no longer sensible in any meaningful way.

an another 9mm - a 9x39mm caliber is a different deal, but a pistol one is just a range toy, not really worth the effort to pursue.
 
This is similar to the build kit I used:
www.opticsplanet.com

FM Products Glock Style 9mm 16 inch AR Forward Charging Builders Kits FM9-16-FS-BLDR Color: Black, Finish: Melonite Coated, $20.00 Off w/ Free Shipping

Shop FM Products Glock Style 9mm 16 inch AR Forward Charging Builders Kits | $20.00 Off Be The First To Review FM Products Glock Style 9mm 16 inch AR Forward Charging Builders Kits...
www.opticsplanet.com www.opticsplanet.com
Comes with everything except a Glock compatible 9mm lower. Now $545.39 and OP is having a 7% off sale till 5/16/22 11:59 PM CT.

I originally paid $427.99 for the kit and $119.99 for the Glock compatible 9mm lower. All in for $548. Less than a Ruger PC, but I wouldn’t have gone much higher for a "just for fun" build.
 
paul73 said:
ok, i will say that.
9mm luger has very little practical sense in a rifle. it was an oddity build while the 9mm ammo was dirt cheap, to get it done for fun and play at the range.
now as 9mm ammo is on par with .223 - it is no longer sensible in any meaningful way.

an another 9mm - a 9x39mm caliber is a different deal, but a pistol one is just a range toy, not really worth the effort to pursue.
Click to expand...
You are not wrong, kind of. The AR9 is a little M1 Carbinish when it comes to practiality, but myself and lots of others would disagree. Its the gun that I shoot the most. PCC has really taken off in USPSA, Steel Challenge, and falling steel matches all over the country. I have also noticed a lot of older folks switching to PCC from a pistol in competitions.
It's just a plain blast.
 
cathouse01 said:
Comes with everything except a Glock compatible 9mm lower
Click to expand...
Is there any way to use Glock mags with a usual ar15 lower? Are there any adapters for magwell that work well, or getting a dedicated lower is the only way?
 
paul73 said:
Is there any way to use Glock mags with a usual ar15 lower? Are there any adapters for magwell that work well, or getting a dedicated lower is the only way?
Click to expand...
Absolutely. A number of companies offer them. Stern Defense makes one of most popular. I ran a "drop in" adapter while waiting for my Form 1 (back in the pre-eForm days). Ran like a top and let me QC my bolt and upper. They even offer them in "AR Kits."

getstern.com

KEY COMPONENTS 4 INCH BARREL KIT 9MM.

Looking for just the key components for a 9mm carbine conversion? Look no further. IN THIS KIT:SD 6 Inch 9mm barrel, threaded .5-36, 1 in 10 twist.SD BU9...
getstern.com getstern.com



BTW, the suppressed 9mm carbine, loaded with 33 rds of 147gr GDHPs that normally rests near my bed would strongly disagree with being called a "range toy." You know, assuming it could read...
 
Awesome, thank you. I didn't know much about FM Products and the price-point and lack of reviews was right on the edge of 'will this be a disappointment?' I'll look into JP also. You guys always come through. Thanks again.
 
I have a New Frontier Armory AR9 that for the little it has been fired has worked perfectly. It uses standard capacity u notch Glock mags.
I built it thinking I could shoot all day for the price of a Happy Meal but the change in ammo pricing upped it to Rib Eye Steaks. 😂

I’m left eye dominant so it blows the gasses into my face and I don’t care for that too much.
 
Thinking I'd like to build a 9mm AR and perhaps later toy with the PCC games. Maybe see if Mrs. Mountain likes it too. My parts pile would get me pretty far in the build after I get a Stern Defense adapter and bolt. I'm a big believer in putting most of the $ for an AR build into the barrel, bolt/BCG, and trigger. I know nothing about 9mm barrels.

@andrew1220 or anyone who shoots in competitions- what barrels are the way to go? Everyone using 16"? Something shorter with some sort of extension and pinned to 16"?

edit- I'm not against buying a complete upper but generally prefer to build something the way I want it. Taccom stuff OK?
 
Last edited:
Mountain said:
Thinking I'd like to build a 9mm AR and perhaps later toy with the PCC games. Maybe see if Mrs. Mountain likes it too. My parts pile would get me pretty far in the build after I get a Stern Defense adapter and bolt. I'm a big believer in putting most of the $ for an AR build into the barrel, bolt/BCG, and trigger. I know nothing about 9mm barrels.

@andrew1220 or anyone who shoots in competitions- what barrels are the way to go? Everyone using 16"? Something shorter with some sort of extension and pinned to 16"?

edit- I'm not against buying a complete upper but generally prefer to build something the way I want it. Taccom stuff OK?
Click to expand...
if you will find a cheap way to use glock mags using standard ar15 lower with an adapter - let me know pls.
as one shown above - stern - was around $400, and i have no desire to buy any more lowers.
as of barrels - all i saw there was a usual suspects list - cmmg-faxon-foxtrot-psa.

like, this one is said to be using glock mags, but, it is short:
www.opticsplanet.com

FM Products FM-9 AR 9x19mm Parabellum Rear Charging Upper Receiver, 5 inch w/ Blast Diffuser Up to $20.00 Off — Free 2 Day Shipping w/ code 2DAYAIR — 2 models

Shop FM Products FM-9 AR 9x19mm Parabellum Rear Charging Upper Receiver, 5 inch w/ Blast Diffuser | Up to $20.00 Off 5 Star Rating on 1 Review for FM Products FM-9 AR 9x19mm...
www.opticsplanet.com www.opticsplanet.com
 
Last edited:
paul73 said:
if you will find a cheap way to use glock mags using standard ar15 lower with an adapter - let me know pls.
as one shown above - stern - was around $400, and i have no desire to buy any more lowers.
Click to expand...
I have lowers, uppers, triggers, etc. Stern 16" barrel, conversion adapter, and bolt are $450 total- relatively cheap.

I'm looking for something suitable for steel games. I don't need flex on the poors level, just suitable for beginner / mid level performance.
 
Cur said:
JP Rifles if you're going to use Glock mags. Buy once, cry once.

If you manage to find a Colt SMG pattern lower you can use notched Uzi mags (or Colt SMG mags $$$$). I would still suggest a JP Rifles upper.
Click to expand...
I have a 9mm that is 100% JP except that it uses a Rock River conversion unit on a standard JP AR lower. The big advantage here is that I can use cheap Uzi mags with a notch cut. If I want to spring for a Colt 9mm mag ($$$) I would also get bolt holdopen. It also means that my SBR lower can take 9mm and 556/223 uppers (registered as 9mm, have not got any uppers yet, but they will be JP).
 
Rob Boudrie said:
I have a 9mm that is 100% JP except that it uses a Rock River conversion unit on a standard JP AR lower. The big advantage here is that I can use cheap Uzi mags with a notch cut. If I want to spring for a Colt 9mm mag ($$$) I would also get bolt holdopen. It also means that my SBR lower can take 9mm and 556/223 uppers (registered as 9mm, have not got any uppers yet, but they will be JP).
Click to expand...
I'm a big fan of JP and if I had already dipped my toes in the PCC pool I'd probably get one.

I definitely want bolt hold-open and for convenience want glock mags. Perhaps a JP upper to start plus a Stern adapter and bolt for a lower I already have? Dunno if that would work.
 
Mountain said:
I'm a big fan of JP and if I had already dipped my toes in the PCC pool I'd probably get one.

I definitely want bolt hold-open and for convenience want glock mags. Perhaps a JP upper to start plus a Stern adapter and bolt for a lower I already have? Dunno if that would work.
Click to expand...
do you plan to sbr it or run a 16" barrel?
 
Rob Boudrie said:
I have a 9mm that is 100% JP except that it uses a Rock River conversion unit on a standard JP AR lower. The big advantage here is that I can use cheap Uzi mags with a notch cut. If I want to spring for a Colt 9mm mag ($$$) I would also get bolt holdopen. It also means that my SBR lower can take 9mm and 556/223 uppers (registered as 9mm, have not got any uppers yet, but they will be JP).
Click to expand...

You actually turned me on to them a long time ago when I posted here about an AR9. I used to use a mag drop in and PWS lower.
I managed to get a YHM Colt SMG lower (shout out to Whiskeywon) and it runs like an absolute top.
 
cathouse01 said:
…The Ruger is good bang for the buck, plus it can use Glock magazines (good if you’re a MA inmate that needs to use pre-bans). I like my Beretta CX4, a bit more expensive than the …
Click to expand...
All good info in your post. I’d say a CX4 is even better for MA people because Beretta 92 prebans are a lot cheaper than Glock prebans.

Also, aside from the Sig MPX, LMT is supposed to be coming out with a 9mm AR that uses gas delayed blowback like the MPX. No idea when it will come out though.
 
Last edited:
Mountain said:
Thinking I'd like to build a 9mm AR and perhaps later toy with the PCC games. Maybe see if Mrs. Mountain likes it too. My parts pile would get me pretty far in the build after I get a Stern Defense adapter and bolt. I'm a big believer in putting most of the $ for an AR build into the barrel, bolt/BCG, and trigger. I know nothing about 9mm barrels.

@andrew1220 or anyone who shoots in competitions- what barrels are the way to go? Everyone using 16"? Something shorter with some sort of extension and pinned to 16"?

edit- I'm not against buying a complete upper but generally prefer to build something the way I want it. Taccom stuff OK?
Click to expand...
I don’t dabble in PCC but I see guys is using SBRs and 16 inch barrels.
@SJan had a sweet SBR setup:
www.northeastshooters.com

SHOW ME YOUR PISTOL CALIBER CARBINES POST THEM PICS

Cx4 and a Remsport (Lonewolf) R9 Nice. Just picked up a cx4 and put a sig Romeo5 on it but still need a light. How do you like that inforce?
www.northeastshooters.com www.northeastshooters.com

This thread might be helpful
www.northeastshooters.com

PCC Advice

Anybody got any advice for someone looking to purchase and eventually compete (IDPA/USPSA) with a PCC ? I have zero experience with them other than to watch others shoot them at matches. I like the look/price of the Beretta CX4 Storm but reviews have not been kind. Anything out there that is...
www.northeastshooters.com www.northeastshooters.com
 
I had just decided to do a 14.5” ar9 build and ordered a spikes colt mag lower a few days ago, so I’ll be watching this thread with much interest.
Being in ma I like the idea of cheap preban uzi mags. Haven’t decided on upper components and will likely just try to be patient and shop for deals/sales. Saw a deal on toolcraft bolts the other day and now can’t figure out where…
 
wcorey said:
I had just decided to do a 14.5” ar9 build and ordered a spikes colt mag lower a few days ago, so I’ll be watching this thread with much interest.
Being in ma I like the idea of cheap preban uzi mags. Haven’t decided on upper components and will likely just try to be patient and shop for deals/sales. Saw a deal on toolcraft bolts the other day and now can’t figure out where…
Click to expand...
I believe this is it. Scroll down the page

 
I had thought about doing an AR9 build but with mp5 mags like the New Frontier C-5 or Quarter Circle 10. I only read into them a little bit but the whole idea behind the mags was availability & the none ass rape prices of pre-ban glock mags
 
milktree said:
Yes.

Unfortunately (as far as I know) there's one guy who makes them, and requires you send him the trigger group.

I understand that what you get back is quite good though.

ETA:

Beretta CX4 Storm Accessories & Parts Upgrades

Upgrade Beretta CX4 Storm trigger hammer guide rod
sierrapapacx4.com sierrapapacx4.com
Click to expand...
I have the SierraPapa hammer/trigger/spring kit in my CX4 and it makes a world of difference. You do have to send them your trigger housing but they give you a nice video of how to remove it (and how to reinstall it when you get it back). They do this because they have found enough variations in the dimensions of the CX4 trigger housings that they want to custom fit the kit to ensure that that the hammer remains cocked and doesn’t fall unintentionally. The kit is well worth the $186.50 (plus $21 shipping both ways via USPS flat rate box). It pretty much does for the CX4 what the Geissele Super Sabra Trigger Pack (at $350) does for the Tavor X95. If you want to go whole hog you can also get their Machined Aluminum Trigger Housing for an additional $350, but then you have to send them your complete lower (kicks the shipping charges to $50). I just went with the hammer/trigger/spring kit for $207.50 all in. With their aluminum housing its $586.50 (the aluminum housing requires the separately priced hammer/trigger/spring kit). If you already have the trigger kit like me you can just purchase the housing (but you still have to send your entire lower).
 

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