I want to complete my 545 collection with a bulgy rpk74 clone. I know K-Var has the milled one at $2500, but I'd like to build a stamped receiver unit. Anyone know where I might find a parts kit or some useful parts other than K-Var?

God, I miss Todd Grove...

SS

Ak builder, COAK arms, Apex

Not to to be a downer here - but there was a discussion I saw recently and the consensus was that a kit, if one was to find one in private hands, would be in the 1500-1700 range.
I have not seen a discussion of building one of them dated post 2008ish. YMMV - and good luck, I for one am mighty interested.

What are you doing barrel wise?

I've heard that some people had issues with Todd. All I can say is I was treated fairly. I mentioned to ORF that I was having extraction issues with a 74 build and when I compared that bolt's machined recess for the extractor spring it was deeper than the others I had on hand (all from ORF). I fixed the problem by cutting off the end of a hex key and dropping it into the recess as a spacer. But, a few days after my call to ORF I was surprised to find a pristine complete 74 bolt in my mailbox at no charge.



This is one of the options I was wondering about. Actually I was thinking of buying a Romanian RPK front trunnion and changing bullet guides on that. I don't have one on hand to determine if that would work or not. Since my initial post here I found a good deal on a complete RPK74 rifle built by Vector and bought it, but I'm still considering building one with an AK-Builder flat and collected parts.

Please do let us know how the M85 Yugo bulged trunnion works out!



I called K-var a month or so ago and asked them about that RPK-027 barrel because the photo they show does not look to be the same contour as the one they use in their milled RPK rifle, nor does it look like the ones that came in the RPK74 Bulgy parts kits. I asked what diameter the barrel shank was and they told me that they were "new generation" RPK 74 barrels and that they were 22mm, not 23mm. He also seemed to be certain that they are the same contour/same barrels they used in the milled RPK-74 rifles they offer. I can tell you guys for certain what the barrel shank is this week as I have one on order and it should be here Tuesday.If it's 22mm, I imagine I could machine a sleeve with an ID of 22mm and OD of 23mm, press it on the barrel shank, weld it in place and then use it in the 23mm trunnion.

SS

Mine has arrived, and it is 23mm!

SS

Please update us. Extremely interested to see how this ends up.

Any progress on this RPK 74 build ?

It's been a long time but, I finally got it to a point where I am confident that this thing is going to work.
First I need to talk about this pic.

On this bullet guide, I cut the caming ramp just to see if an AK74 bolt and guide would work in the M85 trunnion. I didn't want to fit a new bolt not knowing if it would work and I am glad I didn't too.

I didn't see it at first but I knew something was off. Notice in the pick above, the little gap at the front of the bullet guide. Turns out that the rivet hole is too far to the rear, .037 too far to be exact. This will cause excessive fitting to the bolt and feeding issues due to the guide sticking out too far into the magazine as in the pic below.

So, weld or ???. I didn't like the idea of welding on a trunnion so I tried to elongate the hole. After about three attempts I decided, that was not going to work, the rivet kept moving back when they were smashed. So I had to weld it up which turned out, not to be so bad. I used my little Mig at first thinking a good fast weld would produce less heat. Ether I didn't get it clean enough or it didn't like the metal in the trunnion. I went back over it with the Tig and some stainless filler and that work great. Filled up and smoothed out the botched Mig job and still kept the heat to a small area about 1/2" in diameter. Just think - weld fast, cool with air until the orange glow disappears then dunk in water.

Problem #2 didn't have anything to do with the trunnion. It was the AK-Builder rails they use in the RPK receivers. The humps that are suppose to be magazine guides are not big enough so that the mag fit is very sloppy. (Note; This applies to the Bulgy 74s and the Romy 47s) To correct this, I use the Mig welder again and ran a bead across the humps, then sanded them down until I got a very tight fit. I will finish them up after heat treat and final assembly.
After welding.

Now sanded to fit tight.


While trying to keep this as Bulgarian and Russian as possible, I acquired a slightly used Bulgarian bolt and carrier which fit the new bullet guide with a little file work on the corners of the lugs. The ejector has been fit and the M85 one piece center rivet in place but not smashed, just in position for testing. The mag port was cut back a little, I didn't take measurements but, I would guess about .060" was cut to get the mags in. They clear the M85 center rivet but not a standard rivet and sleeve without a clearance cut like NDS does on their Yugo receivers.

New bullet guide installed.


Feed ramp in proper position.


M85 center rivet.


Bolt and Carrier slide into home smoothly.


The rest of it is pretty much a straight forward build. I probably wont get this finish for a long time as I have a lot of builds going at the same time and need to get all the receivers done so they can be heat treated in batches. That's another saga.

GOOD LOOKING WORK

Where are you sending your recievers for heat treat?