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extending your 7.62 bolt to longer calibers(PICS)

3K views 16 replies 9 participants last post by  Braddog 
#1 ·
THIS IS HOW I EXTENDED A YUGO M72 BOLT FOR MY 8MM PROJECT
BUILD AT YOUR OWN RISK........WIDE OAK TREE IS YOUR FRIEND

I WAS GOING THROUGH MY PARTS BIN AND FOUND MY PROTOTYPE EXTENTION.I DID NOT USE IT BECAUSE I DRILLED IT TOO OFF CENTER BUT YOU GET THE IDEA...OH YEAH DONT FORGET TO TAP AND THREAD THE ENDS OF THE BOLT AND EXTENSION.TRY TO USE A ROUND TYPE FIRING PIN TO REDUCE CHANCE OF PIN CHAFFING ON DRILL MARKS WHEN YOU BORE THE F.P HOLE ..A NON TELESCOPING CAR ANTENNE WORKS WELL FOR ME.

PAY CAREFUL ATTENTION WHEN EXTENDING THE SCALLOP CUT FOR EJECTOR,DON'T CUT INTO THE BORE.

ANOTHER ALTERNATIVE IS TO USE A MOSIN NAGANT CLEANING TOOL SLEEVE
THEY COME IN THE $5.00 KITS FOUND EVERY WHERE(HARD METAL)

YOU CAN TAP THE LARGER I.D THEN ADD A THREADED ADAPTER OR CUT A STEP ON THE BOLT AND RUN A DIE ON IT.

ALSO THE TWO HOLES ON THE SIDE OF THE SLEEVE CAN SERVE AS A ROLL PIN REST YOU CAN LOAD A FIRING PIN SPRING ON.

HOPE THIS HELPS.


Cylinder Auto part Wood Metal Nickel
 
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#3 · (Edited)
Car antenna for a firing pin...okay.
Looks like a plan.
I was stuck on the bolt extension for my 8mm conversion.

Note: I found that the #8 bushing from Victor machine is almost the exact dimensions
of the AK bolt shaft. I had one laying around. 8 x 13/32 x 1-3/4, cut to length and weld on.

thanks!


I'm using MG13 mags with an M76 barrel.
 
#4 ·
Don't forget that when you move the ejector back for the longer 8mm you will need to extend the cutout on the bolt stem for it and the area where it goes when the bolt rotates.

Looking good guys!
 
#5 ·
Gunter said:
Don't forget that when you move the ejector back for the longer 8mm you will need to extend the cutout on the bolt stem for it and the area where it goes when the bolt rotates.

Looking good guys!

That is correct. I can model it after my M76 bolt.
I also found a 4mm hex key that I modified for the firing pin.
 
#6 ·
If you have a lathe, I'd consider using either drill rod or a grade-8 bolt that is turned down to the right diameter. Nice and hard that way, and you shouldn't have to worry about the pins getting peened and either breaking or dulling down to light primer strikes.
 
#9 ·
:thumbup1:

10 days ago it was in the white with no holes or trigger guard, now its finished! Holy cow you build fast. Let us know how she shoots.
 
#16 ·
That is exactly what I did.
It was an alteration of the original RPK bolt and carrier for
8mm.

I've got a few hundred rounds thru mine so far.
Situation seems normal. No unusual wear or stress.
 
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