9mm mag block for 5.56 lower....which one?

[God's Country]

Thinking about building a 9mm rifle. I already have a lower and would like to use it, so that means a mag block. I would prefer Glock mags because I already have a bunch. Stern
Defense has a nice design, but ouch on the price ($180). Any others worth considering?

[Emptymag]

Didn't even know they made them for Glock style mags.

Yeah, the price has always been an issue. At one time, that was one of the only options, but now there are dedicated lowers, so it's a harder pill to swallow to buy a mag block.
I'll look at my bookmarks from when I was building my 9mm carbine and see if I find anything...

[DucatiRon]

The Stern works well. Just the mag release is on the side of the magwell and you have to push the release forward towards the barrel. Ok for everyday use but didnt like it for competition. Pay attention to glock conversion blocks. Many do not have an ejector or last round bolt hold open. Many companies build that into their glock compatible upper. Do good research.

I run a top loaded Hans for Colt SMG mags. It has preformed flawlessly in 2 years of IDPA and Steel Challange competiton. Also around $180. It has a steel ejector built into the mag adapter and has last round bolt hold open.


I would suggest a dedicated Glock lower if you are set on glock mags.

And please stay away from the 30 dollar pmag adapters. Those are some junk. For those that dont know they make an plastic insert for a pmag to switch from 223 to 9mm just using the mag. The ejector on the adapter is plastic and fails relatively quickly.

[God's Country]

I may end up going with a dedicated lower. It would certainly be cheaper, but being able to reverse back is also appealing. I'm not set on Glock mags. I need to look at the cost overall.
Odds are I won't use it any more than any other of my black rifles. Hoping the cheaper ammo will peak my interest more.

I'm aware of the mag release, but not the last round situation. Good tip thanks!

It's really a question of whether I want to get a FFL involved with the build. It would be nice to just order everything and be done with it. The closest FFL that is easy to deal with on internet orders is a bit of a drive.

[Emptymag]

Hahn is probably the most known/reliable that I'm aware of.
I can't find any old bookmarks, but here are two threads of mine (COLT pattern) that may have something useful within.

9mm AR15 - Best Way to Build One?


PAFOA Logo 9mm AR15 Carbine Build

I got SUPER lucky to snag my PSA COLT PATTERN mag block for $30 on clearance. I wasn't sure it would be reliable at such a low price, or I'd have bought a dozen and sold them for 2x as much.

[Hodgie]

You might want to give this a good look while it's not super cheap and only a 5.56 mag insirt it only requires a 9mm upper which can be had on sale for cheap at times.

I have seen these run in full auto with zero failures.

https://aimsurplus.com/mean-arms-end...rt-single-pack



Here is a comparability video from the manufacture.

[Hodgie]

The Stern works well. Just the mag release is on the side of the magwell and you have to push the release forward towards the barrel. Ok for everyday use but didnt like it for competition. Pay attenetion to glock conversion blocks. Many do not have an ejector or last round bolt hold open. Many companies build that into their glock compatible upper. Do good research.

I run a top loaded Hans for Colt SMG mags. It has preformed flawlessly in 2 years of IDPA and Steel Challange competiton. Also around $180. It has a steel ejector built into the mag adapter and has last round bolt hold open.


I would suggest a dedicated Glock lower if you are set on glock mags.

And please stay away from the 30 dollar pmag adapters. Those are some junk. For those that dont know they make an plastic insert for a pmag to switch from 223 to 9mm just using the mag. The ejector on the adapter is plastic and fails relatively quickly.

How quickly because I have yet to see any fail from the reviews I have seen including full auto use that were properly set up as shown in the above manufactures video. If your looking or a weekly use 9mm rifle then I would pass on this but to give a 9mm AR platform rifle a shot I think it's a good option without breaking the bank, and a dedicated lower can be added at a later time.

[DucatiRon]

I may end up going with a dedicated lower. It would certainly be cheaper, but being able to reverse back is also appealing. I'm not set on Glock mags. I need to look at the cost overall.
Odds are I won't use it any more than any other of my black rifles. Hoping the cheaper ammo will peak my interest more.

I'm aware of the mag release, but not the last round situation. Good tip thanks!

It's really a question of whether I want to get a FFL involved with the build. It would be nice to just order everything and be done with it. The closest FFL that is easy to deal with on internet orders is a bit of a drive.

You will insanely love your rifle in 9mm. If you run 147 grain subsonics it will even be better. I used a block because I wanted a SBR lower. I would like to add a few short barreled uppers to my collection so it was my best route.

Dedicated Glock lowers usually have last round bolt hold open to my knowledge. No expert there because I went Colt build. If you do go Colt I will warn you. There are about 10 different mag manufactures. Not all mags will function correctly in your build. You are working with stacking tolerances. You might find that a 13.99 mag works fine or like me and only 30 buck mags will work. That is one problem I am very aware of. Basically you buy one of a few and see which one runs the best and return the others.

On a good note a 9mm carbine will basically eat any ammo you feed it. Round nose, Flat nose, conical nose, ammo to long for pistols, dam near anything. I've ran mine a whole year on bad reloads I bought off a customer because he didn't seat the bullet deep enough for his handgun. Over 5k rounds of ammo for under half price. It was a good year for the carbine.

[DucatiRon]

How quickly because I have yet to see any fail from the reviews I have seen including full auto use?

The failure in those adapters are if you apply any and I mean any pressure to the mag while firing. You cannot hold the mag or rest the mag on anything. Seen a few videos on youtube about the failures. Its an instant failure.

One vid.

https://www.youtube.com/watch?v=L0lmtUDrKXQ&t=17s

[Hodgie]

The failure in those adapters are if you apply any and I mean any pressure to the mag while firing. You cannot hold the mag or rest the mag on anything. Seen a few videos on youtube about the failures. Its an instant failure.

Failure to feed or failure as in destruction of the part itself?

Quite honestly I have seen more budget 9mm carbine/pistol builds with major feeding and extraction issues then anything else in the AR world with the net with the exception of the very pricey CMMG rifles and those offered by Wilson. A much as I love PSA their 9mm platforms are very hit and miss. The only good thing about them when you get a miss is the life time warranty.