[tarawa]

Well I figured this needed to have a thread of it's own.
I received the new 5.45 x 39 (23mm) trunion from K-Var and a OOW 5.45 receiver.
1) I drilled the trunion and receiver.
2) Riveted the trunion to receiver.
3) Riveted trigger guard.....so far so good. Mag fits nicely.
4) Test fit the bolt head to the trunion....no go!
5) I had to grind away at the small ramp on the left (ejector) side of the tunion. I believe it is part of the feed ramp. The bolt now goes in and locks into position. (I thought that if you got a 5.45 trunion, everything should fit).
6) Set-up barrel and started to press in the barrel.
7) Noticed that I wasn't quite lined up with the sight base.
8) Set barrel in a vise and used a wrench on the receiver to twist and align the sight to trunion. Needless to say, everything is in alignment, but not without creasing the receiver.....cosmetic, but you think I would have learned from my first build (also creased the receiver in the same spot) JB weld will fix it up.
9) Resumed pressing barrel.
10) As I was getting close, I noticed that the trunion is narrower than the sight base. sight base is .900....trunion cut out is .875
11) Removed barrel. (Noticed some light gouging on the barrel after removal)
12) I guess the next step is to open up the top of the trunion to accept the RPK sight base.

What did I get myself into? Any suggestions?

 

[hcpookie]

can you post a pic? I'd like to see what's going on....

Sounds like you can probably file/mill off the extra material. Only talking .025"...

 

[tarawa]

can you post a pic? I'd like to see what's going on....

Sounds like you can probably file/mill off the extra material. Only talking .025"...

I am going to mill it off. It seems as if the one side is thicker than the other, so the first thing that I have to do is check the center. I may have to remove most of it from one side.

 

[Dirtalert]

What did I get myself into? Any suggestions?

RPK HELL------ABANDON ALL HOPE ALL YE WHO ENTER HERE!


Suggestions? Cold Beer and Fresh Donuts works for me. :smile:

 

[Dirtalert]

Hope you fare better than me G. I drilled and pinned the barrel this afternoon and now headspace is off. This is not funny anymore.

 

[Winn R]

on my RPK's--'47's--I happened to fit the trunnion into the barrel and headspace prior to installing in the receiver.

It just happened that way but I'm now thinking that's a valid proceedure.

Good luck to both you guys.:sorry: My shop's full of consolation prizes--I prefer to look at them that way instead of pricy paper weights.

And generally I can figure some way of salvage that makes the end result even better.

 

[tarawa]

latest update

Went to work today on my RPK after being in New England for a week. I finally got the barrel pressed in, headspaced and pinned. I accidently used an oversize drill bit for the pin hole, so I had to cut some drill rod and harden it. I have my doubts about the hardness of this air hardening rod, so I am going to replace the pin later. Headspace is perfect. With the headspace perfect the siteblock was a little bit forward, so I pressed it in place. It is good that the barrels from K-Var were not pinned or drilled! I believe that the gas tube will fit now. It was too tight before.
I now know why one should use an RPK trunion with these barrels. Although my head space is perfect, there is a gap about an 1/8" between the front of the trunion and the sight block. There is also amn 1/8" of excess barrel showing in front of the trunion. The RPK trunion must be a bit longer where the barrel presses in.
I also had to trim .060" from the rear of the receiver to get the cover to fit. This build has been painful.
The receiver will need some JB weld to fill all the nicks, dings and scrapes.
At least the RPK wood that I bought is beautiful. Let's hope it fits without me ruining it!
I guess that I am about 75% completed of the worse build experience that I ever had.

 

[Dirtalert]

Good to hear your progressing G. I am dead in the water with this project. I ran out of patience and money. I'm still confident I will get my government RPK research grant. What bolt did you use for the 23mm trunnion? I think if I had to do it over. I would have had my barrel turned down and use a 74 kit. I figured just pop the barrel in a SAR-2 and go. Piece of cake. Man, was I wrong! Post some pics when you get it done.

 

[tarawa]

Dirt,
I am using everything from my K-Var 74 kit except barrel, front trunion and stock set.
Things to do:
Rivet rear trunion.
Change gas piston.
Install trigger group.
Putty up the receiver to cover all the dings and dents.
Paint.
Clean the cosmoline from the stock set and install.

 

[Dirtalert]

So, when you got the new trunnion from k-var did you have to turn the barrel down at all or hone out the trunnion, or did it just fit?

I know you said you had to make an adjustment on the trunnion for the bolt to turn.

I'm beginning to think a sar-2 trunnion is a totally different animal than what a mil-spec 23mm trunnion is. I know the bolt is anyway. I'm afraid to have a 74 bolt milled down. It just doesn't look like there would be enough meat left. At this point, I'm starting from scratch. I'll have to romove the sar trunnion, rivit another in, use new barrel or weld up what I have and repin.

 

[tarawa]

So, when you got the new trunnion from k-var did you have to turn the barrel down at all or hone out the trunnion, or did it just fit?

I know you said you had to make an adjustment on the trunnion for the bolt to turn.

I'm beginning to think a sar-2 trunnion is a totally different animal than what a mil-spec 23mm trunnion is. I know the bolt is anyway. I'm afraid to have a 74 bolt milled down. It just doesn't look like there would be enough meat left. At this point, I'm starting from scratch. I'll have to romove the sar trunnion, rivit another in, use new barrel or weld up what I have and repin.

I didn't turn the barrel down or hone the trunion. I had a very hard time getting the barrel started and had to remove it several times to remove burrs that were the result of pushing it in crooked. I then realized that my (xebec) push block was chipped on one of the surfaces causing the misalignment. I had to then shim it to level everything.
I have to work on my press a bit too. It has a little to much side to side motion for me, causing lateral movement while pressing. I am going to install delrin or teflon guides to keep the movement vertical.
I don't know if the "new" 23mm trunion from K-Var is the way to go either. It is definately not the optimum wat to go. All I can say is that you can make it work. Turning the barrel and using the AK 74 trunion is probably a better idea. You still will have to work on the sight base to get it to fit in the trunion.

 

[Dirtalert]

G,
yeah I know the sight base will still have to be addressed. I initially thinned down the ears on the first trunnion. I didn't like how thin they were so my second try I thinned down the sight base and actually pressed the opening in some with a clamp. That seemed to work better and the bolt carrier still slid in and out of the sight base with no problem. Shame on me, I know it's a rig job!

I don't really like the idea of turning the barrel down. I guess that would save me from buying a trunnion since I have a couple of 74 kits. Hate to screw with them though since they look primo and I know from past experience I can build a 74.

 

[tarawa]

Shame on me, I know it's a rig job!

If you want to see a rig job, you should see my sight base. I ground mine with a dremel tool! Before I finsh this gun, I will have to use the JB weld on the site base also!
It is a shame to ruin a perfect AK-74 kit....like I may have done! I will sell my barrel and trunion. I am going to build an AMD-63, using the plum furniture. It should be neat.

 

[tarawa]

Well, I thought things couldn't get any worse...until I misdrilled the rear trunion holes and the rear tang was pointing up in the air when I got finished riveting it. It was hideous looking. I got some practice with the welder and plugged all the holes. I re-drilled the receiver for a new rear trunion (AK-47 type). I re-riveted the rear trunion, cleaned up the receiver, fitted the pistol grip and buttsock and then put it together to the point of looking like a gun...somewhat.

 

[Winn R]

I now realize how lucky I have been with mismatched barrels and trunnions.

When I built a Bulgarian mil set on the early sixties era East German trunnion, all it took was swapping around through different bolts in a box and the trick was done. I remember thinking "it really shouldn't be this easy".

My hat's off to you guys.:notworthy

 

[tarawa]

I now realize how lucky I have been with mismatched barrels and trunnions.

When I built a Bulgarian mil set on the early sixties era East German trunnion, all it took was swapping around through different bolts in a box and the trick was done. I remember thinking "it really shouldn't be this easy".

My hat's off to you guys.:notworthy

Winn,
I have never tackled anything so difficult and frustrating. The lower forearm needs fitting and so does the gas tube. A bead blaster would be helpful along with a bucket of body putty for the receiver. Thank goodness paint hides a lot of flaws.
But I must admit.....it sure does look good to me in the condition it is in.