Anyone done this before? I'm preetty certain I have it figured out but ant help appreciated.
I am asembling a East German STG 941 barrel. I reprofiled it for he AK74 components from the Bulgarian AK74 kit. I am using one of the old Nodak single stack 5.45 receivers (economy $48) which I opened uop for the Bulgy 5.56 waffle mags to fit.
After the lathe work on the EG barrel., the asembly went well. I decided to use a Yugo 5.56 bolt vs the 5.45 bolt. The Yugo bolt and carrier are short bolt lug vs the 5.45 long bolt lug.
The headaspace and everything went well. The barrel does seat maybe .200" further into the trunnion due to the short lug., and so all the barrel components "stack" on this alignment.., no problem there.
All during the build and mock up the rifle cycled, picked up and chambered and ejected round nicely.
As I pulled the barrel for final trunnion to receiver riveting I noticed the small nick on the outside left rear of the barrel near the bullet guide. I did not give it too much thought and I riveted up the trunnion.
I re-inserted the barrel and was just about to do final pins on the gas block and FSB when I closely examined the bolt to bullet guide match up.
hmmm, the barrel setback makes the bullet guide much too far to the forward position to assist in camming the bolt. The bolt still chambers rounds and goes into lockup but only on the rotation from the carrier vs the assist from the bullet guide.
Doh!., I had originally ordered a 5.56 bullet guide from AA-OK in advance of the build., but after a 3 month wait they had not delivered and were out of stock. I canceled that order in January.
Meanwhile I found a 5.56 guide at K-Var>
The Largest AK-47/74 Rifle...
What I don't know is if it has the same rivet location and alignment as the 5.45 trunnion machining. It has a guide ramp that is further to the rear. I hope/presume this is for a short lug bolt. But this is unknown. I will start measuring.,
I'm hoping I do not have to de-rivet as I may be able to remove the 5.45 guide and install the 5.56 guide with a block inside the receiver bottom. If not I'll pull the 6 trunion rivets.
A normal 5.45 long lug barrel insertion in a 5.45 Bulgy trunnion>
A 5.56 short lug bolt headsaced with an East German 5.56 barrel in the Bulgy trunnion with 5.45 bullet guide in place>
You can see the insertion depth difference