5.56 on AK74 kit build
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
UPDATE: A bit of weld on the guide and final assembly and all good., just needs a blast & finish>>
I just finished a 223/556 build using 74 parts, I used a wieger barrel from APEX a east german 74 trunnion I picked years ago, in fact the parts were all east german except for the bolt which is a 5.45 bulgy, yes the barrel needed to be trimmed to fit the rsb and trunnion and the gas block hole drilled, I have several 223 k-var bullet guides but others had no problem with using those guides with 223/556 so i kept the 5.45 guide, my only problem was not setting the rivets on the trigger guard real tight to the reciever, this cause a mis feed problem other than that I consider my rifle to be a workshop type model from eg74 to stg 941 as it would have been the natural progression in the workshops , using polish beryl mags
my wieger will be next in my shop just waiting on restorit to finish the wieger barrel unit
the wieger barrels are very accurate which should be expected from suhl. my wieger will use a 223 bolt bulgy and 223 bullet guide and wieger mags
I used a Henderson 80% with rails installed, I refuse to use ffl receivers in all my builds.
I have attempted to upload the pictures of this build which i posted in another thread on ak 223's here in february
you are a known builder and have alot of experience i think its easy to determine that it may be best to leave the 5.45 bullet guide and trim it if need be, but to answer your question yes the K-var bullet guide holes line up with the factory 5.45 guide holes in the trunnion
Thanks for the input on the 5.56 guide.
But to explain the situation., the 5.45 guide is much to far forward to contact the bolt lug at all. You can see this in the posted pictures.., it does not assist in camming the bolt.
A 5.56 short lug guide has the ramp much further to the rear and will look similar to the second picture in terms of the guide reference to the chamber face etc. At least that is what I hope the 5.56 guide does.
My thought would be to maybe add a bit of weld material to the camming "ramp" and reprofile it to fit your shorter lug bolt. Not sure that I would want to try it installed though.
Thanks., yes., that is plan II if the 5.56 bullet guide proves to be a no go. I'm going to drill & pull the 5.45 guide in any case. Then a matter of mocking up the 5.56 guide for fit & function from there.
I'm hoping from the info that the 5.56 K-Var guide is gtg for the short bolt. Kinda a bummer as the rifle cycles, feeds and extracts "as is" but I'm not comfortable with the bullet guide set up.
I guess one unknown variant (at least to me) of not staying with the 5.45 long lug bolt vs the short lug. Oh well., not the first head scratching build issue.
I built one using a Romy G AKM 7.62X39 trunion. Had to install a 5.45X39 feed plate and Dremel the bottom of the trunion's locking surfaces so AK74 mags would fit.
I built one just like the way you are doing it. E. German bbl and Bulgy AK-74. restorit assembled the front end for me. Used the 5.45 bolt. Runs great!