10MM DI AR Carbine build

[JGSFAB]

Sometimes its bad/good idea ordering parts to build something with leftovers you didn't need.
I ordered a 224 Valk upper and didn't need the bolt then I realize 224 Valk shares its rim with 10mm and I've been enjoying my G21 converted to 10MM. I've also enjoyed having a G21 and an AR45 blowback except for an out of battery experience. That really got me thinking about DI 'ing my large caliber carbines.
Green Mountain has some barrel blanks again so I grabbed a 40cal blank.
Now the gas system, needs to be short as possible, like up against the handguard short lol.
So no room for a stepped gas tube, really need a really high gas block.
Solution 1 , 0.936 block bushed and off-center bored (needs 0.181 off-center on a standard low pro gas block) 0.650 to 0.700 barrel diameter
Solution 2 , custom which is more than within my resources. In fact I could see my self doing a couple DI conversions. Will work on the 45acp, just needs more porting.
Hmmm.

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[kmk1012]

Sounds like a wintertime project, hope you mail it on the first try. Would be a neat little action, I wonder if the bolt would need to be a light weight one.

 

[JGSFAB]

I found a build on Reddit so its a "been done" and certainly works. I feel like you need the "hot stuff" loads which I have a AA#7.

 

[JGSFAB]

Worked on the gas block and barrel some , one short short gas system needs a straight gas tube so I plugged n welded a .936 block and off center bored it to .700 is. Printed out a jig to use the 3 jaw, worked fantastic. Used PLA printed solid, would recommend.

 

[edzz]

Very interested to see how this turns out, Please keep us informed, if this plays out as expected you should have a soft recoiling carbine.

 

[JGSFAB]

Hopeful it will shoot fast and safe

 

[JGSFAB]

Well everything is coated and ready for assembly. More pics tomorrow , too much stuff going on.

 

[JGSFAB]

Well first rough assembly. Forgot to grind out the extension for large single feed... and of course mag sits too high (expected).
Other than that it looks good.

 

[JGSFAB]

It cycles light reloads (180gn , 7gn unique)... feeding still needs some work. Might need to radii the breech a bunch. Trying some mag work first. Mag still sits super high.

 

[Happyguy]

I have a factory DI in 10mm and to get it to really run I am having to load max from old AA books for #7 but it does run. They run a coiled gas tube.

 

[JGSFAB]

I have a factory DI in 10mm and to get it to really run I am having to load max from old AA books for #7 but it does run. They run a coiled gas tube.

If I can get the mag to work I think it will work with std. loads. I do have a few cans of AA #7 for some hot loads.

 

[Happyguy]

I am running grease gun mags in mine, the first one I built way back when was an Olympic Arms upper and it ran great on grease gun mags also.

 

[JGSFAB]

I am running grease gun mags in mine, the first one I built way back when was an Olympic Arms upper and it ran great on grease gun mags also.

45acp mags seem to fit an AR15 BC better than the 10mm mags. I did some whittling on the poor Bolt carrier and bolt. Also made a new mag catch as I cut up the original...
It feeds from the bolt catch!
Cerakoted all the modded and new parts in Elite Blackout then it's back together and more testing...

 

[JGSFAB]

PICS

 

[Happyguy]

It is a project. Hoping you complete it soon.

 

[JGSFAB]

Today was pretty good, it's picking up from the mag on cue. 50% of the rounds didn't have enough poop to kick the bolt back far enough. Gonna make a zero weight buffer and add more lube. Recoil spring might be a 308 spring, feels stiff.

 

[JGSFAB]

Well 11.5gn of AAC7 does the job , ejects 4 o clock 8ft away every shot. Recoil is extremely satisfying, good boom and very light.
Wondering if lighter loads will run with a can but WTF is the point of the mighty 10mm if your not going to run full power loads?
I load some twice and no signs of the brass getting tore up.

 

[MichaelH]

You know, you can buy this….but I guess you'd miss out on the project fun.

10mm DI (direct impingement) Upper Receiver Group

Our Macon Armory 10 mm direct impingement upper receiver group is based on the standard AR15 direct impingement action used in our AR45 . Our barrels are Cerokote coated and hand-crafted with a 1:10 twist and 5/8 x 24 muzzle thread using 4140 Chrome Molybdenum steel, providing both accuracy...

maconarmory.com

And it's a grand, and they're custom built too. Maybe they're friendly and share tips?

 

[JGSFAB]

You know, you can buy this….but I guess you'd miss out on the project fun.

10mm DI (direct impingement) Upper Receiver Group

Our Macon Armory 10 mm direct impingement upper receiver group is based on the standard AR15 direct impingement action used in our AR45 . Our barrels are Cerokote coated and hand-crafted with a 1:10 twist and 5/8 x 24 muzzle thread using 4140 Chrome Molybdenum steel, providing both accuracy...

maconarmory.com

And it's a grand, and they're custom built too. Maybe they're friendly and share tips?

If I didn't make it small window side charge it would have been easier. I'd say they all need max velocity 10mm loads.
Only thing I'd change is possibly making a indexing handguard nut / gas block to get that port an inch closer to the bullet.

 

[MichaelH]

Honestly, I'm not the kind of guy who'd normally be into AR's, but when I found out you can build and modify them—super easily—the draw was there. You're beyond me with altering the parts, but I now relate.