[Dirtalert]

Well I've managed to stuff this barrel into a SAR-2 receiver. It's at the max now and headspace is loose. I can't tell what holding it up from going further. Possibly the feed ramp or it is just seized up. Any thoughts?
TIA

 

[Winn R]

Dirt --George is talking about doing the exact same thing.

He just got the K- var barrel to stuff into a standard '74 trunnion.

Now -- You've been sharp -- only a hair away from a complete gun!!

It should be apparent what's stopping it. If not, it's little trouble to take it back out (I've never gotten one right the first time).

Look on the trunnion to see how far the other went in.

 

[hcpookie]

OK I wanna know... feed ramp?

 

[Dirtalert]

Now -- You've been sharp -- only a hair away from a complete gun!!

Winn,
If you are referring to Rapunzel's hair, then yes you are correct. :smile:

I had this Sar-2 put back although I don't know why. It's a rough looking one. It was supposed to be NIB. Well by Century's standards anyway. I thought it would be a fitting sacrifice to the Gods of knowledge. Like many quests for knowledge the prize you see at the end of the road may be just another milege post reading:----ANSWER 50mi.

Now my question is what the hell is holding this thing back! It Might be apparent to the trained or "sharp" eye, neither of which are attributes that my eyes possess. You should have heard the 20 ton press groan and creak and then the horrible sound of flying steel and crashing glass. I must really consider moving that press away from my garage windows. :smile:

The worst part of the whole thing is trying to maneuver that damn bipod in between the cross braces of the press. Next time maybe I'll just remove it.

I'm going to take a closer look at the thing and see if I can figure out what's holding it up. If not out it comes.
As always thanks for the help and advice.

 

[Dirtalert]

OK I wanna know... feed ramp?

Pookie,
That would be my guess but only a guess. I have to see if can stick a feeler guage between the barrel and the feed ramp. Looks awfully close.

 

[Winn R]

Winn,
If you are referring to Rapunzel's hair, then yes you are correct. :smile:

You should have heard the 20 ton press groan and creak and then the horrible sound of flying steel and crashing glass.

As always thanks for the help and advice.

Life around the Dirt house must be interesting. And we are obviously not referring here to what, in the southern vernacular, we used to call "close as a Red C*** Hair".

Are you using a lube between the barrel and trunnion?

And I've never been ashamed to choke a barrel in a vise and take .001 off just to make life a little easier. It's always nice to wear your problems down.

It may be possible to knock a Red C*** Hair off of the barrel where it's getting stopped and not encounter the area contacting the bolt face.Or, it would be my preference to work on the trunnion but they are harder to get into.

But you will have to pull the barrel out to do it.
How tight was the fit with the original barrel?

 

[Dirtalert]

Winn, I initially used the black paste that xebec sent with the press kits. I started pressing the barrel and realized it wasn't straight, so I pressed it out again. I was out of paste so I used wheel bearing grease as it was the only thing I had. The barrel went in as expected but got to that point where it would not go anymore. I thought it was the feed ramp but there appears to be space between the bottom of the barrel and the ramp. At least enough space to insert a small gauge stainless steel wire. Couldn't find my feeler gauge. I can't see a thing that would cause it not to push more. Would you suggest soaking it down in penetrating oil? (liquid wrench or something). I'll have to use something to coat it when I press it out.

The original barrel pressed out easily. If anything it was too loose.

Life around the Dirt house can best be described as: Hours and Hours of sheer boredom, interrupted only by brief moments of insanity and chaos.

 

[hcpookie]

What about this -

The area around the barrel pin should be smooth. A slight raised bump in that area could cause this to happen. May not need to remove the barrel. OTOH if there is a bump on the trunion where the barrel pin sits, same thing maybe.

Another thought - if it went in crooked and raised a shaving that could cause it to seize as well. Can you remove it and sit the barrel side-by-side to the original? I'd like to see if there are any bright metal tracks where the barrel may have gotten shaved. I saw this when I was playing with my I-Beam press.

 

[tarawa]

I will doing the same thing, but I will start with a new K-Var AK-74 kit. I will check and see where the original barrel sits before I press it out.

Dirt,
Where are you getting the RPK wood??

 

[tarawa]

Dirt,
Is it possible that the barrel is in the whole way, but the breech block isnt designed for a 5.45 x 39 bolt face?? Just a thought. Maybe there is just too much room in the locking lug area.

 

[Dirtalert]

I will doing the same thing, but I will start with a new K-Var AK-74 kit. I will check and see where the original barrel sits before I press it out.

Dirt,
Where are you getting the RPK wood??

G-
I read your post the other day about Interordnance having some RPK stock sets. We'll see what shows up if anything. I have a plum rpk plastic set.

 

[Dirtalert]

Dirt,
Is it possible that the barrel is in the whole way, but the breech block isnt designed for a 5.45 x 39 bolt face?? Just a thought. Maybe there is just too much room in the locking lug area.

I don't know but I tried to press it in further again today same thing.
Thanks

 

[tarawa]

I don't know but I tried to press it in further again today same thing.
Thanks

Dirt,
I just got off the phone with Andre from Global. I was asking him questions about his new 23mm trunions. He said that it wont work with the AK-74 barrel because it is machined for the 7.62 bolt, not the 5.45. I guess if the locking lugs are smaller on the 5.45 and it will not headspace correctly. He said the barrel must be turned down and the original AK-74 trunion must be used wit the AK-74 bolt.

 

[Dirtalert]

Dirt,
I just got off the phone with Andre from Global. I was asking him questions about his new 23mm trunions. He said that it wont work with the AK-74 barrel because it is machined for the 7.62 bolt, not the 5.45. I guess if the locking lugs are smaller on the 5.45 and it will not headspace correctly. He said the barrel must be turned down and the original AK-74 trunion must be used wit the AK-74 bolt.

G-
What I am using is a sar-2 receiver. It had a Romanian barrel in it. I believe the 5.45 romanian barrel is 23mm. The bulgy AK-74 barrel is 22mm. I am using the bolt that came with sar-2 to check headspace with. Do I have to change trunnion to ak-74 and turn barrel down? I'm confused.
A sar-2 + RPK barrel should work in theory. Help me out here G. :smile:

 

[hcpookie]

SAR-2 = 5.45 x 39 so you should be OK there.

You're sure of the measurements? Perhaps Winn's idea is the best idea... IF and I mean IF that's reversed, the trunion is 22mm and the barrel is 23mm, then that's the problem - too tight of a press fit and the thing is just tooooo tight to budge past that point - too much bearing surface to adhere to.

SO.... Winn always favors using a disk brake hone to take off .001 - in fact that's really about all you can take off... then you could make the press fit more manageable.

Hrm maybe not - I just got this info from
http://www.aa-ok.com/AK_Tech/aktechinfo.htm


BULGARIAN BARREL: O. D. DIMENSIONS Chamber .871" (22mm w/ .004 - .005" press fit)
ROMANIAN BARREL:Chamber .908"(23mm w/ .003 - .004" press fit)

So doing the math here, assuming the RPK-74 bulgy barrel is the above measurement, you are looking at a real nice & loose press fit. Can you caliper your barrel journal? Let's see if perhaps its just a bit on the large size.

 

[tarawa]

Dirt,
If the Sar-2 is 5.45 you should be ok with the bolt fitting the trunion correctly, but the barrel diameter is still too big to press correctly.


hcpookie,
Do you think honing the trunion is better than turning the barrel to the correct diameter? I just figured that Global builds these RPKs commercially and wouldn't steer me wrong.

 

[hcpookie]

Just parroting what Winn said, I think it may help.

I've seen another build of a SAR-2 > RPK-74 conversion but no mention of how easy it was.

If its already pressing in that far, I would guess that turning on a lathe wouldn't help, but you never can tell.

FWIW

 

[mike26038]

Dirt I just thought..

of a couple things here...

The RPK-74 bbl should be about .908" and the SAR about .907" so you could be producing shaving that are holding you back. You could press the bbl and have a look see. That really aint to big a deal to do....

OR

I noticed you mentioned Xebec, so I am assuming you are using his press blocks??? If this is the case, have you checked to see if the trunnion push block is hitting the rear sight base causing the hangup?? When I did my build this is what was stoping the bbl from going in all the way..

Just a few thoughts.....

 

[Dirtalert]

I noticed you mentioned Xebec, so I am assuming you are using his press blocks??? If this is the case, have you checked to see if the trunnion push block is hitting the rear sight base causing the hangup?? When I did my build this is what was stoping the bbl from going in all the way..

Mike,
Initially this is what I thought the problem was. The push block would contact the rear sight block, but I made a mod on the push block and it clears. It still would not press any further.
Thanks

 

[Dirtalert]

Thanks for all the tips on this issue. You guys are first rate.

I'll press out the barrel and see what's what. Probably won't have a chance until Sunday.