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12-24-2009, 06:11 PM #1
Replcing a Bad SKS Barrel -Pictorial (long post)
I posted this with the SKS Boards, but I thought I'd share it with NES Members too!
My fourth attempt at replacing a "bad bore" Yugo barrel on a good receiver with a Chinese Type 56 barrel is something I thought you guys would appreciate. So I took pics this time.
Here is the Chinese barrel on the receiver stub that I bought from Numrich. It's covered in surface rust, but will clean up and accept cold blue. After this pic, I soaked the barrel down with PB Blaster penetrating oil, wrapped it in plastic and let sit for a week. Most of the surface rust wipes off with a rag afterward, and the moving of the rear sight block and unthreading of the receiver stub goes much easier too.
1. Prepare sight block for movement.
The pin on the rear sight block must be pushed out from left to right using a 3/32" punch
2. Move sight block forward
With the receiver stub resting on the vise jaws and the barrel pointing down through the vice, a drift punch can be used to tap the rear sight block forward on the barrel until there is enough room to fit a quality 22mm wrench accross the flats of the barrel lug.
3. Remove barrel from receiver stub.
With the wrench in place and the stub secured in a strong vise, take a three foot pipe and place it over the wrench. In a short concise burst, break the threads loose in a counter-clockwise direction for the right handed threads. The barrel should twist out by hand from here.
(no picture - I didn't have three hands! But I'm sure you get the gist of it.)
4. Repeat steps 1-3 with Yugo barreled action
Keep the Yugo receiver, throw the sewer pipe out (after you get the sight goodies off!)
5. Screw Chinese barrel into Yugo receiver
As you can see, the Chinese barrel did not fully index into the Yugo receiver. It came up about 45deg short. My previous replacement went 15deg past proper index and I will elaborate on this condition later.*
6. Check replacement barrel indexing
To allow the new barrel to fully rotate clockwise to proper index, material had to be removed from the receiver. The amount of material is MINISCULE to allow for the remaining 45deg rotation. I used a 3M metal buffing pad on a right angle buffer. I cannot tell you how much material that I removed, except that it was probably only the crests of the milling tool marks that came off with the buffer. With medium pressure, I buffed for about a minute at high speed, checking frequently by inserting and removing the barrel by hand until it came to about 5deg from indexing fully.
7. Properly index barrel
Using the wrench and a hammer, I snugged the barrel clockwise until the bottom lip of the extractor releif (cut-out in the chamber face) matched evenly with the upper right rail inside the receiver. Don't worry if your index mark from the replacement barrel doesn't match the index mark on the receiver. IT JUST WON'T HAPPEN. The two existing index marks were stamped on different mating parts and WILL NOT ALIGN.
8. Tap sight block toward receiver
Using a hammer, lightly tap the front of the sight block back toward the receiver until it stops moving. You may have to adjust the angle a bit by tapping side to side until the bore in the block mates up with the bore in the reciever. Your retaining pin that you tapped out in Step 1 will not go back in until you drill out the hole with a 3/32" bit and reaming ever so carefully until the pin is snug but starts through from right to left. Using the punch, seat the pin into place.
A properly indexed barrel will look like this.
The bolt should drop snugly into the recess in the receiver.
The finished product is now ready for stripping, cleaning and Cold Blueing. I use the Birchwood Casey three stage kit.
*note: If the new barrel goes past indexing before it tightens against the receiver, align it properly and use a prick punch in several areas on the mating surfaces of the barrel lug and the receiver to prevent rotation during use.
9. Take to a Gunsmith for proper HEADSPACING!!!
I am not a gunsmith, and only play one on the internet. Anyone who tries this at home does so at his/her own risk. All alterations should be checked by a gunsmith before operating this mis-matched barreled action as a functional firearm .
Have fun. 8)
12-24-2009, 09:47 PM #2
Be sure to update when you get it complete with stock, hardware, and to the range.
12-27-2009, 05:11 PM #3
After buffing the metal bare and smoothing out all the nicks and scuffs, I applied the three stage Birchwood Casey cold bluing. Then I dug through the parts bins and came up with an Albanian bolt carrier, a Yugo bolt, a Romanian mag, a Russian stock set, Chinese trigger group, bayo and cleaning rod.
Kind of makes a neat looking gun when done.
Happy building guys!