9mm AR help/suggestions

[ArmedRPh]

Greetings fellow INGO'ers

I have an SBR'd AR lower that I'd like to put a 9mm upper on. I've built a few uppers in my time, so I'm not too worried about the general process, but I would like any feedback/helpful hints you have around:

1. I've seen a few comments around the Stern 9mm magwell conversion system. Anyone have extensive time on one? Happy with its performance so far? Buyer's remorse?

2. Any suggestions on any changes that I need to make on my buffer? I've seen more than a couple of comments about needing to run a heavier buffer (H2), but would like some local feedback if you have any experience with it.

3. Any specific missteps you've had in your 9mm upper build that you wish someone had told you about before you did it. (I'm looking at an 8.5 inch barrel running glock mags and I will run a can on it, if that helps)

Thanks ahead of time for sharing your experience.

Mike

 

[CPT Nervous]

I run a CMMG Mk-9, which is a Colt style AR-9. Mine is an 8 inch barrel with an integral suppressor.

I don't have any experience with the magwell conversions, but I will tell you to run a heavier buffer. Get a 9mm buffer. You'll want something heavier than an H2. I ran an H3 for a while, but the heavier 9mm buffer is much better.

Make sure that you check the ejector and that it's tuned properly. It will have to be lined up properly with the bolt. Also make sure that your bolt does not go more than about 1/4" past the bolt catch when you pull the charging handle all the way back. There are spacers you can buy, or you can use quarters.

 

[Simon6101]

I have been running a Stern Defense and love it. I have tried to beat it up by using a Binary trigger on it and it is still going

 

[gmcttr]

...Get a 9mm buffer... Also make sure that your bolt does not go more than about 1/4" past the bolt catch when you pull the charging handle all the way back. There are spacers you can buy, or you can use quarters.

If you use a 9mm buffer it will be longer than a standard carbine buffer and will not need a spacer. This assumes you have a carbine buffer tube and not the longer A2/rifle extension tube.

If a carbine buffer is used and allowed to have full travel and the magwell conversion provides last round hold open capabilities, the bolt slamming into the bolt catch is likely to damage or break the bolt catch.

 

[Ggreen]

Colt mags are the ticket. 32rd mags at midway for 18 bucks on a regular basis. Taylor freelance +10 extension run 30. Together they have been 100% reliable for me.

I use a Macon armory magwell adapter. It's slick as snot and drops mags free for fast swaps. He is also my go to for barreled uppers. I use a faxon bolt and picked up a guntec 9mm buffer assy from primary cheap. You will have to tune the ejector to your install, but that's easy.

 

[jrainw]

Ramped bolt
$2.25 in quarters.

 

[ArmedRPh]

Thanks everybody. I appreciate the feedback.