7.62x39 confusion

[bkbville]

I want to begin to cast boolits, and I want to start with my SKS and Saiga.

To keep costs down I want to use the Lee 312 155gr mold.

What I don't understand is what sizer do I need for this?

I've gone through about 15-20 threads and I'm not exactly figuring it out:

I read in one place, use them "as cast" and so use a .314 to attach the GC and not really size them.

In another (lenghty) article they say size to .312.

Some seem to say 'bigger is better'

Can someone clarify this for me?

Also - if I use a Lee 309 mold for some 30-06 - should I size that exact? (for an M1)

What if I use the 309 in a 7.55 Swiss?

[Ole]

What is the bore of your barrel?

I have a Chinese SKS and a YUGO SKS.

The Norinco has a measurably larger bore than the YUGO.

Example: I sized (.312") two pure lead 2R155's. The test slug for my Norinco went through without much issue. The rifling marks were very modest. The test slug for my YUGO took a good bit of effort to get through the barrel. The rifling marks were a good bit deeper in the same size bullet.

[Ole]

FYI:

I would be willing to send you a couple pure lead bullets for you to slug your barrel with.

PM me your address and a dollar to cover shipping and i'll get you 4 pure lead slugs. Then you'll know better where you stand.

[Maven]

Ole is correct: BBl. dimensions of SKS' vary by country of manufacture and probably era of production as well. You'll have to slug your clean, well-oiled bore to know what your final "size to" diameter, and possibly, mold choice should be. Btw, this is also true of your .30-06 and 7.5 x 55mm, although .309" may fit the 7.5 quite well.

[bkbville]

The SKS is a Yugo - I haven't slugged it yet - nor the Saiga.

Let me generalize the question a bit - do I match the boolit size to the what I slug the barrel (groove surface to groove surface)? Or should it be larger or smaller?

So if the barrel slugs out to .311, would I then size the boolits to .311?

Some of what I've read would lead me to believe with a .311 slug you may even want to go .312? (which with an FMJ bullet would certainly not be a good idea)

Or do I want the boolit a little smaller than the groove (but larger than the land-to-land)? (e.g. I have friend that loads .308 bullets for x39 - the lee die set even came with collet for both .311 and .308)

I would like good accuracy, but would compromise some if I can use what I load in either rifle.

I might still have a lead sinker I can use to slug the barrel (hard to find in NY - you can't get lead sinkers here any more) to get the true numbers on the barrel, but I want to understand the general concept.

[StarMetal]

The SKS is a Yugo - I haven't slugged it yet - nor the Saiga.

Let me generalize the question a bit - do I match the boolit size to the what I slug the barrel (groove surface to groove surface)? Or should it be larger or smaller?

So if the barrel slugs out to .311, would I then size the boolits to .311?

Some of what I've read would lead me to believe with a .311 slug you may even want to go .312? (which with an FMJ bullet would certainly not be a good idea)

Or do I want the boolit a little smaller than the groove (but larger than the land-to-land)? (e.g. I have friend that loads .308 bullets for x39 - the lee die set even came with collet for both .311 and .308)

I would like good accuracy, but would compromise some if I can use what I load in either rifle.

I might still have a lead sinker I can use to slug the barrel (hard to find in NY - you can't get lead sinkers here any more) to get the true numbers on the barrel, but I want to understand the general concept.


My SKS is Yugo too and it's barrel groove DOES mike out at .311 so I size .313 for it and it shoots great.

Joe

[Buckshot]

..............Welcome to the board bkbville. Whew, new to cast boolits and starting out with an auto loader :-) I have an SKS made in Romania. I bought it so long ago I don't recall when I got it :-) Come to think of it, the last time I held it was when we moved to town in 2000! Hopefully it hasn't evaporated on me. I decided to try cast in it but sure didn't spend any time experimenting.

I had the Lee C312-155-2R and loaded up 10 rounds each of 3-4 different book loads for jacketed ammo. Setting myself up for failure, eh? :drinks: The carbine functioned perfectly, ejecting the empty brass with authority, and not a bobble in feeding. I was absolutely amazed to find that all 10 rounds from each load actually printed on the target paper at 50 yards. In fact a couple loads actually produced what could charitably be called groups!

IIRC the best was about 4.5". I do not recall any problems (like leading) when I cleaned it afterwards, but as I said, it WAS quite some time back. While a 4.5" group at 50 yards isn't anything to carry around in your wallet to show people, it surely exceeded what I had expected to see with those loads, as they all equaled or exceeded 2,000 fps.

As was suggested, slug the barrel to see what you have. Joe mentioned, " My SKS is Yugo too and it's barrel groove DOES mike out at .311 so I size .313 for it and it shoots great." You do want to cast to at least the groove diameter, and better yet a thousandth more. In Joe's carbine, he's probably fitting the boolit close to the throat, which is a fine idea if the boolit is large enough, and if the case will chamber with a boolit of that OD.

While I suspect the SKS will have a chamber generous enough to allow chambering with a slug close to throat OD, it's a good thing to make sure before letting the bolt slam a round into the chamber and pulling the trigger to see what happens.

I'll let others who've intelligently spent time with their SKS's in working up cast loads give you some pointers in that regard.

....................Buckshot

[Bret4207]

No cast through my SKS yet, but in the other 35 or so rifles I load for I like my boolits +.002 give or take. Some may even go +.003. You NEVER want them smaller than groove size, much less bore size.

BTW, if your SKS is the Yugo 49/56 (IIRC) turn that darn gas switch to "OFF". Nothing worse than chasing brass all over God's green creation when you don;t have to.

[jonk]

In general, you should size cast bullets 1/1000" over groove diameter to start. If you can do 2/1000 and still chamber then by all means, do so. You can keep bumping it up as long as it will freely chamber, though at some point even if you can chamber it there is a distortion effect that will start to erode accuracy.

[MT Gianni]

My son was over for his birthday a few weeks ago and we took the SKS and Handi-Rifle in 7.62 out. The Handi is scoped with a 3.5 Weaver and sighted in @ 1"high 50 yards. He took 2 shots to break a gallon milk jug @ 175 yards off hand. The SKS ran about 3.5" @ 50 yards with the same load. His comments were " not much good is it." The load is built for the handi but the potential is there for the cartridge. Look at the bottom of this page for Castpics and go to the data and loads section. lots of good info is there.

[bkbville]

In general, you should size cast bullets 1/1000" over groove diameter to start. If you can do 2/1000 and still chamber then by all means, do so. You can keep bumping it up as long as it will freely chamber, though at some point even if you can chamber it there is a distortion effect that will start to erode accuracy.

Thanks Jonk - that is what I wanted to know....

I dug up some lead fishing weights - maybe my last two, so I'll slug the barrel soon.

[FAsmus]

bkbville;

The 7.62x39 is easily one of the most fun cartridges to load for that I've become involved with.

I bought a Yugo SKS, never slugged the bore but instead fired a few as-cast Ideal 311284s ( as-cast size 0.314 ) into a snow drift, recovered the spent bullets and measured them.

Bore size was 0.301, groves measured 0.3135. on one and 0.3125 on the other.

I tried some several bullet designs including the Lee 312-155-GC fired as-cast at 0.312 and the GC sized on at 0.314 with moderate results - groups typically going into 5x2.500 @ 50 yards. Then I bought an old Ideal 311466 on eBay. This mold casts bullets right at 0.313. I sized on the GCs at 0.314, loaded with a good load of 1680 and my groups go into 5x2.000 at 100yards all day long.

I like the 311466 because I can load to proper overall length to fit the magazine and still have enough bullet out front for the body of the bullet engage the origin of the rifling when the round chambers. Its kind of "magic bullet" for the gun you might say.

Good evening,
Forrest