sks gas system fouling

[Harmon_Greer]

Will shooting bullets with gas checks in my SKS clog the gas system with lead?

i have the lee 155 grain mould and the 113 grain "soup can" and would like to know if they can be utilized without possible unreasonable cleaning or terrible inaccuracy.

I would/could cast them out of straight linotype if needed.

Harmon

[StarMetal]

I wouldn't cast them out of straight lino. A good mixture is 50/50 WW's and lead. Even just WW's are good. Size so bullets are about .001 to .002 over groove diameter. If you get a bad lead wash in your gas system then your load isn't exactly right. With correct loads SKS shoot very well and they shoot a long time between cleaning. Expect them to tear your brass up, possibly even losing some with their violent extraction. All in all very fun rifle with cast. I find the Lee 155 grain bullet shoots the best in mine.

Joe

[Larry Gibson]

I've found less fouling in the SKS and AK gas systems from GC'd cast bullet than when using milsurp 7.62x39. I'd also suggest an alloy of 60/40 WW/linotype as about the hardest (it is around 18 BHN) neccessary for the 155 gr Lee bullet. As Starmetal suggests if you get lead wash you're not using the right lube. I also concur on straight WWs working well (I add 2% tin just for better castability). I use Javelina and Lars 2700+ with excellent results. Starmetal is also correct on sizing; Mine drop at .313" or so and i just seat the GC and lube in a .314" H die in the 450.

Without modification the cases do get "slung" quite hard and far. I have modified my gas tubes so they eject milsurp or equivelent loads similar to an M1/M14. With the heavier bullet and full power loads of 4895 the brass is slung a little farther but it is finable and not damaged.

Larry Gibson

[Harmon_Greer]

im gonna try the lee soup can with 4227

any starting loads that WILL cycle the action?

[Ole]

I have used 16.0 grains of IMR 4227 with the Lee 2R155 bullet and it cycled the action of my SKS just fine. The round was noticeably lighter than 18.0 grains of WW680 with the same bullet.

For alloy, I used straight WW's, water dropped into a bucket with 2% tin added. No leading was noted at all in the barrel. A little in the gas system after 100 rounds. Nothing serious though. Took less than 5 minutes to clean it out.

[JIMinPHX]

I just loaded up a few of Ole's boolits & tried them in an SKS this morning (Thanks Ole:drinks:). They tested out at 24bnh. I lubed them with LLA & loaded them over 15 grains of 2400. My average speed was just a hair under 1800fps. The action functioned reliably. Standing at 30 yards with no rest or sling, I shot groups that were smaller than a baseball.

The boolits were about .0015" under the groove diameter of the gun that I tried them in, so I expected bad fouling. & questionable accuracy. I was pleasantly surprised. There was just a hint of leading at the chamber mouth & just a thin film of lead for the first 1/4" on the inside of the gas tube & on the face of the piston. Everything cleaned up without any trouble.

From looking at the recovered boolits, it appears to me that they didn't obdurate fully into the grooves (as would be expected from an undersized hardcast boolit). The boolits also deformed less than some flat point 30-30 slugs of similar hardness that I have shot at about the same speed. I think that I am going to anneal a few of these & try them again to see what happens.

[Ole]

I just loaded up a few of Ole's boolits & tried them in an SKS this morning (Thanks Ole:drinks:). They tested out at 24bnh. I lubed them with LLA & loaded them over 15 grains of 2400. My average speed was just a hair under 1800fps. The action functioned reliably. Standing at 30 yards with no rest or sling, I shot groups that were smaller than a baseball.

The boolits were about .0015" under the groove diameter of the gun that I tried them in, so I expected bad fouling. & questionable accuracy. I was pleasantly surprised. There was just a hint of leading at the chamber mouth & just a thin film of lead for the first 1/4" on the inside of the gas tube & on the face of the piston. Everything cleaned up without any trouble.

From looking at the recovered boolits, it appears to me that they didn't obdurate fully into the grooves (as would be expected from an undersized hardcast boolit). The boolits also deformed less than some flat point 30-30 slugs of similar hardness that I have shot at about the same speed. I think that I am going to anneal a few of these & try them again to see what happens.

What kind of SKS did you shoot those in, Jim?

I have a Norinco and a YUGO and my YUGO has a good bit smaller bore than my Chinese one does. I slugged both with a pure lead bullet and the YUGO bullet was notably tighter.

[JIMinPHX]

It's Chinese. The bore is loose as a goose. It's like .3135" to .314. The whole thing looked like it had almost no wear on it. I think it was just made that way.

[Ole]

It's Chinese. The bore is loose as a goose. It's like .3135" to .314. The whole thing looked like it had almost no wear on it. I think it was just made that way.

Yeah you'd never guess how well those things can shoot by looking at them. :)

[JIMinPHX]

I was amazed.

[Bret4207]

My Yugo SKS has the gas cut off so I can use it "single shot", sort of a straight pull action. Very nice for a reloader!

[Maven]

Harmon, If you use CB's that fit your SKS' bore and don't push them to milspec velocities, your gas system will have few lead deposits. One thing you can do to prevent this is to coat the gas piston, particularly the front surface with something like white lithium grease, which will allow for easy removal of any Pb deposits there.

JIM in PHX, My Type 56 also has a ~.313" bore. Past experience with both Lee and Lyman mold dimensions, particularly those designed for the SKS (both had a 311 prefix), led me to seek out Veral Smith (LBT), who produced the same C.E. Harris-designed bullet as shown in an earlier post. On a good day it will shoot the 1" center out of a target @ 50 yds. from my as issued Type 56. Btw, the bores of most SKS's, with the principal exception of the Yugo's,* are chromed, which is why they look so good and clean so easily.


*Yugoslavia didn't have access to chromium except through the USSR. The political situation between the two (Yugoslavia was a thorn in the Soviets' side.) kept the supply of chromium to a minimum.

[StarMetal]

Maven is right, the Yugo's aren't chrome lined. If you're not shooting surplus corrosive ammo who cares. The bores on the Yugo, in my opinion, are pretty consistent and very well made. The whole rifle is very well made. Bret is right about the gas shut off valve and that's how I use mine. No sense in chasing brass or having it damaged. The Yugo's are more robust rifles. When I bought mine I got an unissued one, glad I did. I feel a better grease to coat the cylinder and piston with are the anti seize ones. I say this because they seem to stay on better and longer. That may be because of their high temperature rating. I don't use it on my Yugo because I don't need to, but I use in on the cylinder pin of my Ruger Old Army. Found that grease works fairly well in hindering black powder fouling.

Joe

[JIMinPHX]

I didn't know about the gas shut off on the Yugos...Interesting. I remember somebody saying something about removing his gas piston to make the rifle into a straight pull so that he would not need to chase brass. Also interesting about the chrome bores... It seems that several inexpensive surplus guns have this (usually) expensive feature.

[StarMetal]

I didn't know about the gas shut off on the Yugos...Interesting. I remember somebody saying something about removing his gas piston to make the rifle into a straight pull so that he would not need to chase brass. Also interesting about the chrome bores... It seems that several inexpensive surplus guns have this (usually) expensive feature.


There are two Yugo models, the one has a grenade launcher and this is the one with the gas cutoff for obvious reasons.

Joe

[JIMinPHX]

Maven, are you saying that you had a mold custom cut to duplicate the Harris boolit, but just a little bigger in diameter? If so, did you try the gun with the "normal" size boolits first & then try it with the fat ones after? How much difference did you see?

[Maven]

JIM...., What I did first was slug the bore several times and then look at what molds the major manufacturers offered. Both Lee Precision and Lyman cut molds for the C.E. Harris-designed bullet, but I feared both would drop CB's that were too small for my Type 56's bore and I wasn't willing to gamble with my $$. LBT was willing to cut a mold to the spec's. of my bore for a fair price and so I had them do it. To answer your specific question, no I've never tried the Lee and Lyman undersized CB's in my SKS (I size mine to .314".), but tests with other undersized CB's indicated poor accuracy. Over the years I've discovered that my SKS will shoot quite a few CB designs surprisingly well if they cast large enough initially for me to size them to fit. This includes an ancieint Ideal .32-40 PB design and a 195gr. "fat" Loverin w/GC that I use in my Arg. Mau. and Finn. Nagants. The CB I need to retest is the group buy Lee 30-150-TL (unsized) if I can figure out how much, or more precisely, how little CLAYS, Unique or Blue Dot I'll need to use. Btw, I'm not expecting such a load to operate the action and may just remove the gas piston to spare myself mangled cases.

[Harmon_Greer]

is the 155 lee the best bullet for the sks? or would the soup can work too?

[JW6108]

I didn't know about the gas shut off on the Yugos...Interesting. I remember somebody saying something about removing his gas piston to make the rifle into a straight pull so that he would not need to chase brass. Also interesting about the chrome bores... It seems that several inexpensive surplus guns have this (usually) expensive feature.

That's the easiest solution.

[Larry Gibson]

For a bolt action SKS the Yugo with the gas cut off is the nicest. If you don't have a Yugo the easiest is to remove the gas piston. However this leaves a large chamber for gas bleed off. I noticed a small but noticeable decrease in velocity and large fluctuations of the ES. Since you have to remove the gas tube to remove the piston it isn't much harder to remove the piston extention and spring. I removed the spring and turned a steel tube (made out of a section of old barrel) to replace the spring. This allows the gas piston to be replaced and it is then non-functional and stationary leaving a very small gas expansion chamber. More consistent accuracy and more consistent velocities resulted. It only takes a few more seconds to change out the spring for the tube on the piston extention rod.

However, since I abhore a bolt action SKS I simply got an extra gas tube and modified it to allow quicker gas venting. This softened the bolt velocity and allows "reasonable" ejection of cases with little to no damage to them. The softer ejection makes them much easier to find.

Larry Gibson

[StarMetal]

Larry's modified tube is a good that doesn't leave the SKS permanently modified. One thing to never do is shoot the SKS without the gas tube and piston. You'll get a serious blast of gas and possibly other stuff back into your face.

Joe

[JIMinPHX]

If you don't have a Yugo the easiest is to remove the gas piston. However this leaves a large chamber for gas bleed off.
Larry Gibson

I may make up a non-functional dummy piston to replace the original. If it has a good snug fit in the piston housing & a little center hole for gas bleed off, it should keep most of the fouling out of the places where we don't want it.

[superior]

I fired my sks paratrooper saturday with the gas piston removed and had excellent accuracy.
I didn't notice any ill effects whatsoever.

[Maven]

superior, Starmetal was referring to the tube that contains the gas piston. Trust me, you NEVER want to fire the rifle without having it locked securely in place. You are correct about accuracy being essentially the same with or without the gas piston in the gas tube.

[StarMetal]

superior, Starmetal was referring to the tube that contains the gas piston. Trust me, you NEVER want to fire the rifle without having it locked securely in place. You are correct about accuracy being essentially the same with or without the gas piston in the gas tube.

Paul,

I can tell you this. As you know my Yugo has the gas valve. I've compared shooting it (recoil wise) with the gas on and gas off. I have a scope on my SKS and with the gas on the eyepiece sometimes bumps my glasses. With the gas off not a chance of it. I'm using a pretty stiff load by the way. Far as accuracy gas off or on I haven't noticed a difference. I do have an idiosyncrasy with semi-autos and that is I feel the cartridge gets chambered the same way and the bolt locks up the same when in the semi-auto mode. In other words I think those two things are more consistant then yanking the bolt by hand. Like I said though I haven't noticed a change in accuracy. Just a quirk of mine.

Joe

[superior]

OOps! ur right, maven. i didn't read carefully.

[badgeredd]

However, since I abhore a bolt action SKS I simply got an extra gas tube and modified it to allow quicker gas venting. This softened the bolt velocity and allows "reasonable" ejection of cases with little to no damage to them. The softer ejection makes them much easier to find.

Larry Gibson

Thanks to Larry's modification, my type 56, made in China with Russian parts, functions flawlessly without the violent bolt movement and ejection.

I've been using a modified 311291 (lapped to drop @ .314 for my .313 bore) in mine using AA2015 for 1950 fps, and 15 ES. After I added a modified Williams peep sight to it I can consistently shoot a sub 2" group at 70 yards. I'm happy with it! As for leading or fouling, I get more fouling with Milsurp ammo. No leading at all with Lar's Canauba Red. My boolits are right at 16 bhn with an alloy of 20% railroad journal babbit mixed with WW.

Edd