Jump to content
Brian Enos's Forums... Maku mozo!

38 in an AR9?

Recommended Posts

Did my first build a little while back using budget receivers and a bunch of other brand parts to complete my AR 9.  It's built on a 556 platform and I took the Endomag route.  I either got incredibly lucky or was given a lot of really good advice from tech departments, probably a little of both.  At well over 1000 rounds it's worked flawlessly without a single misfire or jam using 9mm ammo from 100 to 150 grains.  It's set up to have the option of using a magazine adapter and Glock or Colt mags however I haven't tried it.


Maybe I should count myself lucky and leave it alone however with the similarity between the 9 and 38 rounds, I'm wondering if there's a way I could have a simple reliable option to use one or more of the 38 rounds.  If anyone has any information or input I'd be glad to hear it.

Link to comment

Hmm. 9mm is 9x19, 38S, 38SC & 38TJ are essentially 9x23, but straight walled case. Kinda doubt you will find a barrel that will work with those. If you are talking about 38 special or 357 mag, if they did make a barrel and mags that would work, it would be a serious issue getting them to feed right with the case rim (and could possibly be an issue with the 38S, as it it also semi-rimmed.)

If you want a different caliber, your best options are 40, 10mm, or 45.

Link to comment
  • 3 weeks later...

Yes on the .380, with both of them having the same diameter it seems, at least in theory, to be possible.  With the 9mm casing and overall length being longer maybe that distance makes it a non-starter.  After looking into it further I think the ability to do it is more of a mute point that I originally thought.   If it even were possible you'd spend more money to have an alternate conversion type system that would allow you to use smaller less powerful ammo that for the most part is less abundant and more expensive that regular 9mm ammo.....in 2021 that's not a very good option.


I've started looking into fringe 9mm ammo options at both extremes of grain weight from as low as 50-55grn to as high as 185-190grn.  My thinking is these are really better options for having a varied use and outcome as opposed to .380 which has the obvious feed question.  If anyone has experience with low or high 9mm grain weights out of a 10"-16" 9mm barrel I be interested to hear what you have to say.

Link to comment

need to check if you can use 380 in comp? I have used 380 in 9mm before - works.  OK I need to clarify this comment, 380 100 grain bullets in 9mm cases ! Not 380 bullets in 9mm gun!


Edited by Texaspaul
Link to comment

Unless you want to be the least popular guy at your range, please don't shoot .380ACP at a USPSA match... that damned brass causes all kinds of problems if it gets into folks' 9mm reloading process. The only person hated more is the guy with a 9x21 :roflol:

Edited by StealthyBlagga
Link to comment
On 7/20/2021 at 10:23 AM, StealthyBlagga said:

Unless you want to be the least popular guy at your range, please don't shoot .380ACP at a USPSA match... that damned brass causes all kinds of problems if it gets into folks' 9mm reloading process. The only person hated more is the guy with a 9x21 :roflol:

Not true. 38 Super folks had bounties on their heads back in the day when real men shot SC in Open!

Link to comment

Chillywig in WV...went to school in SW PA and had some fun in WV playing club rugby many years ago.  I like the engineering part of it all almost as much as using the products.  I like the sense of accomplishment from taking a bunch of parts no one else would consider putting together and then making it work reliably.  My AR9 has parts from 15 different manufacturers.  The variety wasn't on purpose, it was just the direction it went as I gathered info and bugged tech departments.  The tech people at mean arms, cmmg, and ballistic advantage were a big help, that said I'm sure they're glad I'm done calling.  My attention span even with things that work is short and I figure the greatest number of options you can give yourself for reliable multi-purposing is worth looking into.  To me one lower you can swap a few basic parts on and have options for 22, 223/556, and 9 seems more practical than lugging around 3 firearms.  I haven't done any competitions but a twist on the 3 gun where reconfiguration for 3 calibers on 1 lower is part of it could be interesting.  Texasdawg, you mentioned to smaller and the bigger stuff and I'll looked at the Berrys site.  I don't have reloading know how or equipment but I bought a brass catcher, a de-primer, and a big bottle of white vinegar a while back and using the poor man's cleaning method I'm developing a nice collection of cleaned once fired casings.  I know one thing for sure, real tired of store hopping and standing out front of sporting goods stores waiting for them to open.

Link to comment

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...