Hey guys do any of you know if you can run a CMMG Mutant with an RDIAS? Thinking it might be a fun host. Or if not what AR that accepts ask mags in 7.62x39mm will work ya think? I know the MGI Military Hydra is another option.

The mutant is based on the AR10, so it can not be used with an AR-15 conversion device.  I have a couple of MGI lowers.  They work great with AK mags.

Scott

I had contacted CMMG a while back about the MK47 as an RDIAS host.  They said the bolt carrier would need machining as they had to on their post samples they made.  I guess it needs a sear trip machined into the carrier.  I also asked the spacing between the upper lug to the the fire control group if it is AR15 or AR10 spec and never got an answer on that.  Originally I read FCG back was AR15 and FCG forward more AR10 spacing which is why the bolt carrier and charging handle are proprietary.  Now I am not sure.  There are no shops locally I can look at one and not really willing to take a $1000+ gamble.  I saw another thread the RRA AK mag AR might work but no success posts.  I know a few guys have had great success with the MGI setup.  The problem is finding/getting the lowers without having to buy the whole rifle and standard uppers need to be modified to work and end up very thin after machining to clear the AK mags.  Michaels Machines used to make AR-47 receiver sets but the website is gone and not sure he does anymore.

I too have been running the MGI setup for years.  I agree that availability has been spotty and wish they would make more magwell options or even keep producing some that they stopped making.
I wish I never sold my GG magwell setup as I would like to use that with the CMMG Guard setup.
They also made Glock magwells but are no longer available.


Friend of mine did buy a spare 556 magwell from Windham and it worked fine on his MGI setup: https://shop.windhamweaponry.com/collections/mcs-multi-caliber-system
Their AK magwell looks cut more and I'm sure more compatible with more AK mags than the MGI AK magwell.

PSA is another option for uppers and lowers but also has spotty availability.  
I bought some of their stripped KS47 uppers that are machined from billet when they had them in stock.
Before these came out, I was getting the old DPMS Hi Riders or Lo Pro's milled out for the wider AK mags.

I'm fortunate enough to own both the GG magwell and a large frame (.45 ACP and 10mm AUTO) Glock magwells are for blowback setups.  The Guard lower (I have one in .45) has the mags lower than the MGI.  But the Guard lower is not low shelf so my DIAS won't work without modification.  (As these MGI magwells are no longer available, I am not interested in selling so please don't bother to ask)

The original MGI AK 7.62X39 won't allow a Russian style drum (the one with the lever to load the drum without taking the back off) to lock up.  I'm guessing that is why the newer AK magwells aren't as deep.

The PSA 7.62X39 uppers I got use standard AR upper receivers.  The carriers look to be modified for use with AK mags.  I bought some LAR-47 upper receivers from RRA that are for AK mags but have not gotten around to switching the upper receivers.

Scott

Hmm... I have a 9mm Guard and it is low shelf.  Works with my RDIAS with no mods.

For the PSA KS47, the billet version does take AK mags.  Here is a link: http://palmettostatearmory.com/psa-ks47-stripped-upper-receiver.html

To be honest, I have not searched the PSA site much.  I am on the email list to see what is on sale.  I once did look at the KS-47 stuff, but the uppers were out of stock.  The stuff that I have bought through the emails at a discount in 7.62X39 has all used standard upper receivers meant for use with a standard magwell AR.  That is why I bought the upper receivers from RRA.  I'm currently in the middle of another project.  Who knows, when I'm ready to start the 7.62X39 project the KS-47 stuff might be back in stock.  I have tried PSA CS and they have not been helpful.  They have really good prices on the stuff they put on sale.  In the almost two years that I have been on their email list they have not listed KS-47 stuff.  Even with the cost of buying the upper receivers from RRA to convert the the PSA uppers for AK mag and drum use, the PSA is still less money than RRA.  RRA does use chrome lined barrels, but all the uppers are 16".  So I have the cost of having the barrel shortened and rethreaded.  RRA also doesn't have pistol length barrels.  So to have a RRA barrel shortened to around 7.5" would be even more money to pay for that custom work.  I bought a "PSA AR47 16" Mid-length 7.62x39 1/10 Nitride 13.5" M-Lok Free Float Upper - With Hybrid BCG & CH" for $380 shipped.  I also bought "PSA 7" AR-47 7.62x39 Upper W/ 2A Armament M-Lok Rail & KAK Flash Can - W/ BCG and CH" for $520 shipped.  At least that is what I have chosen to do.  There are several ways to get there.  This is the direction I am currently going.

Scott