Chamber casting the SKS: Am I doing this wrong or is my gun kaput?

[Aaronbern]

HI, hope everyone is having a good November. Long story short I have a 1955 Tula SKS that was sold to me as a Vietnam "bring-back". It was without papers so I was more expecting a beat-up early import. It is well-worn with pitting under the stock and all the signs of some time in the jungle or in grandpa's damp closet. It shot well with commercial ammo, well enough to ring an 8 inch plate at 100 yards consistently. I wanted to get into CB loading for it so I slugged the bore at .312. In my preparations I decided to do a chamber casting. I was shocked at what I found. The bore measures .314, ok, a little worn, but the throat is GARBAGE. With a micrometer and a dial caliper I',m getting 0.319 just ahead of the rifling and 0.340 just past the case-neck! (see attached pic) Am I doing something wrong? How is this even possible? I was expecting a little throat erosion but .340? There is a very faint line where the case-neck ends at 0.345.

Maybe this rifle was used in combat, thousands of rounds of corrosive ammo is quick succession, or shot with corrosive surplus and put away wet.

Has anyone else seen these kind of chamber dimensions? All I've found in searching is a service offering chamber reaming to ENLARGE the throat! Will this even shoot Cast? I'd like to see some other chamber castings of SKS rifles, both worn and as-new to compare. What do you think is going on here?

[Jniedbalski]

Looks like a deep cut military chamber to me. I haven’t slugged any of my guns just use the biggest cast that will fit the chamber. .310 to .312 bore should be common but your .314 sounds a little big.if you used carosafe it does expand .004 or.005 thousands After a short amount of time. I have seen .070 to .080 thousands past the end of the case neck in ar 15 but .319 seems very long for the lead. Mabe they used a cut down 7.62x54 R reamer instead of using a new one. The Russians where good at making what they had work. I thank it should shoot fine. Just find the biggest bullet that will chamber and go shoot. I have had good luck with the lee .160 2R tl gas checked bullet designed by ed Harris. It just works .one good thing is you never have to trim your brass for being over length.

[Aaronbern]

measurements were made 1 hour after casting, all diameter.

[Jniedbalski]

What is the size of a fired casing at the neck? Just wondering?

[Aaronbern]

fired case (yugo surplus) are 0.342 at the case mouth.

[junkbug]

I remember reading that the barrels of water cooled machine guns would "egg-out" like that. Yours is not really terrible. But certainly heavily worn. Try the largest boolit that will freely chamber and see how it shoots.

[RU shooter]

fired case (yugo surplus) are 0.342 at the case mouth.

What's the neck ID of that fired case you can load a bullet .001 or so under that dia

[Larry Gibson]

That is a pretty common Soviet chamber. It is not an anomaly or "shot out", it is a normal style Soviet chamber. You'll find many SKS and MNs with similar style chambers. Basically the chambers were cut with a pretty long throat with no shoulder/step at the case mouth and with generous dimensions. The chamber throat just tapers from the neck diameter down to groove diameter.

Yes it will shoot cast bullets. I suggest one of 150 - 160 gr that casts at .315/.316. You'll want a GC mould also. Size at .314 - .bullet diameter as cast but probably not larger than .316. Might look at NOE or Accurate moulds. You'll also want to use a "hard bullet" by either ALLOY, WQing or HTing. COWW + 2% tin WQ'd out of the mould generally works well. A 150 - 160 such cast bullet loaded over 24 - 27 gr H4895 should work well.

[Aaronbern]

Thanks for the tips everyone, I plan on using the Lee 160gr powder coated and gas-checked, cast from hardball (50/50 lead and linotype). I'll have to experiment with it like everything else in this hobby. I've been eyeing H4198 and Reloader-7.

[Maven]

"I'll have to experiment with it like everything else in this hobby. I've been eyeing H4198 and Reloader-7." ...Aaronbern

Those are good powders to start with, Ab. As for moulds, I use a NOE ~160gr. GC (C.E. Harris design), which fit the bore of my Type 56, Chinese SKS (new) perfectly. It casts a tad larger than .316", but I size it to .316" - .3165" and get good accuracy @ 50 yd. from the "as issued" Type 56. Btw, I seat it to 2.125" OAL and use no crimp of any kind, as I found crimping adversely affected accuracy.

[starnbar]

I have a couple sks and they range from early 50s to chicom 80s and they all have generous throats I didn't buy em for tack drivers with 5 sons who drop rifles out of tree stands they served me well in that respect and 2 of them shoot damn fine out to 100 yards I am talking 5 shots you can cover with a quarter.