MGMan805

Running a 7.62x39 upper on a full-auto M-16 lower

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Just wondering if anyone has put a 7.62x39 upper on a M-16 lower and got it to run full-auto properly?  What did you have to do to make it run?

Mine will run semi-auto, but not full-auto.

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My friend put his on my RR. It functioned perfectly. I do know he changed out the buffer and buffer spring to run it.

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2 hours ago, Ryo said:

My friend put his on my RR. It functioned perfectly. I do know he changed out the buffer and buffer spring to run it.

Thanks Ryo.  What is a ‘RR’?  Any idea if he went heavier or lighter?

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Is it a full auto bolt carrier?

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56 minutes ago, MGMan805 said:

Thanks Ryo.  What is a ‘RR’?  Any idea if he went heavier or lighter?

registered receiver

 

4 hours ago, MGMan805 said:

Mine will run semi-auto, but not full-auto.

bolt bounce.

I have one, used it many years with a MM AK mag lower, then switched to ACS mags on a m16 lower.

I cut my 16 barrel down to 11.5" and run a MG7 can. I do run a h3 buffer and a super heavy spring as my gas port is too large.  Runs like a champ.

The keys to a 7.62 upper, file the bolt tail down unless you have a extra long firing pin(mine was pre long FPs) to prevent light strikes. Heavy hammer spring and the aforementioned heavy buffer spring as well as heavy buffer.

if yours runs perfectly in semi, its bolt bounce.

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Taylor makes good points. I do believe the buffer my friend installed was a heavy one. 

Yes RR is registered receiver. Wish I had a DIAS but my RR runs reliably. 

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Thanks guys.  If I ever get to the range I will give the suggestions a try.

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Posted (edited)

I put together a 10.5" upper using a Faxon barrel and installed a Wolf heavy hammer spring to pop hard Russian primers.

It runs 100% on top of a RR factory auto sear as well as when using a RDIAS.

It's one of the more interesting MG's as 7.62x39mm out of the short barrel is more of a challenge than 5.56mm is...

I should add that because Faxon drilled the gas port the correct size (after I returned it due to short stroking) I'm able to use a carbine or "H" buffer and it cycles fairly slow for a 10.5".

Hope you get it running correctly. Feel free to ask more questions. They're awesome when you get 'em working right! 

Edited by openbolt

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6 minutes ago, openbolt said:

I put together a  7.62x39mm 10.5" upper using a Faxon barrel and installed a Wolf heavy hammer spring to pop hard Russian primers.

It runs 100% on top of a RR factory auto sear as well as when using a RDIAS.

It's one of the more interesting MG's as 7.62x39mm out of the short barrel is more of a challenge than 5.56mm is...

I should add that because Faxon drilled the gas port the correct size (after I returned it due to short stroking) I'm able to use a carbine or "H" buffer and it cycles fairly slow for a 10.5".

Hope you get it running correctly. Feel free to ask more questions. They're awesome when you get 'em working right! 

 

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I had a colt 762x39 upper and it ran like a top on a reg. reciever. I also set it up to run with the East German Plastic core ammo, almost no recoil and didnt miss a beat. The magazines were the key whenI got it running back in the 90's . At that time the only mags that worked were the ones made by G-tec.

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Since this came back up I will add the dura mags are better than the ASC mags. ive had ASC mags fail and and the dura mags havent

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