barrel installation

[Weed]

I finished receiver build up today I'm pretty pleased with results a couple of my rivets didn't come out as well as I wanted, but it will do. It's hard to keep from ringing the receiver with riveting tool. I caved sides in slightly and made a sort of turnbuckle and jacked it back apart within a couple .000 bolt works fine. My latest problem is I miked Barrel and used a set of snap gages on ID of trunnion I only come up with about .0015 interference fit I think this is aplenty ,but looking at previous posts Several of them say their should be .005 interference Could someone please enlighten me on this? Any and all help is appreciated Weed

[Virginia Jake]

I think that 0.0015" might be a little on the light side. I have read of the fit going as high as 0.005". I think that 0.003" is plenty.

Virginia Jake

[bsn]

The trunnions are not always round, try taking measurements from a few different locations you are probably fine.

[Weed]

BSN you must be a walking encyclopedia on AK builds you are correct the trunnion wasn't round It varied .003 It averaged out to a little less than .003 press and yes it was a pain to get in. I started with a rubber mallet and a block of wood I got it about 1/2 way pretty easily then It got a little stiffer I parted off a piece of brass and laid on top of barrel and made a funky looking brass part to put through receiver to support trunnion square and pressed it the rest of the way Its kinda tricky to get it true to push between lugs. I got it all together Didn't wait to finish the receiver, thought I'd cold blue it later I just wanted to shoot it . So after tying to tree and pulling trigger with string I thought it was safe to shoot it It fired from tree good. Then I shot it correctly It works fine Now I need to figure front sight out It is shooting to right But it functions well Thanks to all again Weed

[bsn]

I clean my barrel and trunnion with Scotchbrite then coat everything with Lee case lube (won't freeze hard and cause problems) then freeze the barrel and heat the trunnion/receiver to 250-300 degrees, you have to work fast in heavy gloves but it will go together with very little press effort. I use a 3/4'X8" bolt that has been ground down to match the trunnion and run it through the magwell to supprt the trunnion.

[Packrat]

Weed, if you need help on the front sight, remember to chase the round: if the gun shoots right, move the sight right; if it shoots low, screw the sight post in. With the "C" tool for adjusting the sight, it's not to difficult to adjust pretty accurately. I use a penny under the ram to keep from marking the cross-pin. (Yeah, I know--who cares if it's marked?)

[Weed]

Packrat,Bsn Thanks for advise I ended pressing barrel in the hard way I suppose I did use a little sneeze on the end of barrel before installation .I had a bad experience a few years back using heat and freezing a part, then assembling Tried to put a bushing in a pulverizer yoke and put the bushing in dryice or cardox I got it out of the fire system in a bag Then heated yoke up with 2 rosebuds I tried to put them together and it went in easy 1/2 way then stuck I was better than a day building a strongback big enough and used a 50 ton jack and heat to get it back apart Not a fond memory. Anyway these things are addictting I want to do another one and with what I learned from you guys and what I learned the hardway I think the 2nd one will be even better. I did get the sight to move to the right with a brass sleeve and a press I guess they make a tool for doing this Hard to judge with a press I thought I might have bent barrel But sight came in fine and repeated at short range and at long range I think if it had bent It would not be accurate at short and longer ranges The only thing is the pin sticks through side of sight a little more on one side than the other about .012 to be accurate Thanks again and I hope to be of help to you guys as you have to me Weed

[Packrat]

Weed, the front sight won't be centered. (It could be, I guess, but that would mean that everything was perfect or the errors cancelled out.) As long as you can adjust it to zero, you're OK.