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Saiga 12 new barrel and bolt issues


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I recieved a Saiga 12 that needed the barrel replaced. I bought a new 18 inch barrel off of somebody that was sold as a second because of chamfering.  I made some scribe lines on the receiver where the old barrel was so I would know how far to push in the new barrel. I installed the new barrel. The new barrel had a longer Tab? than the original barrel (to improve feeding issues?) . 

 Anyway, To cut to the chase. I thought I installed it properly until I noticed that the bolt wont close into battery. (the bolt wont rotate into the front trunnion lugs).  Note...I already drilled and put in the barrel pin and drilled the gas port holes..

 Do I -  Remove barrel pin and pound out the barrel until the bolt closes, redrill for the the barrel pin and fill the gas port holes , re-drill gas port holes??

  OR Do I - Grind down the trunnion lugs so the bolt will rotate into battery?

 

I have built several aks from original barreled parts kits but never from a new barrel.

 This is my first experience with a Saiga 12

Please help,

Thank's,

Craig

post-51182-0-59030600-1476216976_thumb.jpeg

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Can you lock the bolt into the barrel without the carrier in place?

 

Can you tell exactly what feature is conflicting and preventing the bolt from going into battery?

 

Without pictures this kind of question is rather hard to diagnose.

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Shoot a picture from above and below. Get some colored sharpies and put red on all the bolt surfaces and blue on the back of the barrel/ locking surfaces. I's hard to see what's going on with white on white. Also that will let you know what is hitting first.  If the barrel is too far forward or back, when the camming groove in the carrier forces the bolt to turn, either the front or back edge of the lugs on the bolt won't clear into their grooves. It looks OK from the position of the extractor to me, but if you are looking from the magwell, you can see the interaction much more clearly.

 

Also, I don't want to be rude, but let's eliminate some obvious stuff. Is the bolt's camming lug properly indexed into the carrier? 

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I think I discovered the problem..

 I removed the barrel pin today and gradually pushed the barrel out until the bolt would rotate into the trunnion lugs. I think I had the barrel in too far.  

 How can I re-drill and re- pin the barrel without risking the barrel moving? 

 Can I fill the groove in the barrel where I originally drilled with solder or JB weld and then re-drill?

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Go up a size in the barrel pin. use the shank of a drill bit for the new pin if you can't find a suitable rod closely sized.


p.s. I think ginsboy2003 on youtube has some videos about dealing with that particular issue. He's got a lot of good AK building / correcting content.

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Go up a size in the barrel pin. use the shank of a drill bit for the new pin if you can't find a suitable rod closely sized.

p.s. I think ginsboy2003 on youtube has some videos about dealing with that particular issue. He's got a lot of good AK building / correcting content.

Would you happen to know what size of drill bit I should use to drill the pin hole and what size I should use as a barrel pin? How much larger should the pin be compared to that of the hole?

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You can also run a bead of weld in the barrel pin channel and just drill it out and re-use the OE barrel pin. 

You're gonna want to use an end mill of the appropriate size, to drill it out. Also, you should pick up a set of calipers if you're doing this kind of work. You need to be measuring things in the .001-.002" areas for this work.

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  • 1 month later...

Ok, I got the barrel tig welded and properly installed and headspaced.  What kind or type of end mill bit should I use? there are a bunch of different types. I will have to order it because they dont sell any within about 60 miles away. I think the barrel pin size is 5/32 but its tapered.  but it seems a 5/32 drill bit will fit into the hole. I used a regular drill bit the first time.

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  • 2 weeks later...

I think the barrel pin is 5/32 so that means that I would need a 9/64 bit which I cant seem to find anywhere!  Unless I get a 5/32 bit and somehow make a barrel pin one size up (whatever that might be?) Any ideas???

 

#21 or #20 would be a close oversize for 5/32.  Never forget that you have basically 4 types of drill bits to work with...  Fractional inch, number, letter, and metric.  A good drill size chart will give you the sizes of each in decimal inch, in order from smallest to largest.  You want the pin to ideally end up a thou or two bigger than the whole for a tight drive fit.

 

I would for sure take the advice to use a sharp end mill seriously.  Shotgun barrels are not overly thick so you won't have a lot of room for oversizes.  With something like an AK rifle barrel, there is simply a lot more metal to work with, so if you are fitting a new barrel to a used trunnion, it's simpler to just use the first oversize to begin with, and know that you have a couple oversizes beyond that if you screw up or need to rebarrel later.

Edited by Netpackrat
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also, if you need to buy tooling, ALL the sizes of everything can be had from MSC direct. Sadly they bought out Enco, which was cheaper and had better organization for mills and drills.

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