Fine tuning the sks

[NSP64]

Has anyone 'fine tuned their sks? what have you done and does it seem to help. I am going to make a recoil buffer, have done a trigger job. My Yugo won't cycle with the loads mentioned in the articles here, so I got to looking, the gas piston has a lot of slop and I'm probably getting blowby. I'll try to make a teflon ring for the piston.

[mooman76]

I can't remeber exactly who it was but someone here said he got his SKS to shoot 1 moa. I turned it into basically a bolt action though!

[Bret4207]

If you go over to Accurate reloadings cast bullet page there's a guy named Starmetal Joe who claims he got his SKS shooting "one ragged hole" groups. I never saw any targets to prove it, but you could ask him what he did.

[Larry Gibson]

I've "tweaked" several SKSs over the years. Can't say it was "fine tuning" as I wasn't trying to make a silk purse out of a sow's ear. I wanted to keep the SKS funtional "as is" but wanted some improvement in accuracy (with decent ammo - not foreign milsurp blastin' ammo). I have bedded them, adjusted the trigger pulls and modified the gas system for smoother, less violent ejection. It worked as most of them would shoot 2-3 moa with issue sights at 100 yards and easily holds 10 ring on B27 target at 200 yards from sitting or prone positions.

If that's what you're interested in I can expound a little and perhaps add some pictures when I get home in a week or so.

Larry Gibson

[trickyasafox]

That sounds pretty neat larry-

was it expensive to tweak them out to that level?

[RU shooter]

the biggest accuracy gains are to be found by feeding it good ammo and mounting a peep sight to the rear of the receiver and doing a good trigger job on it.

[Larry Gibson]

That sounds pretty neat larry-

was it expensive to tweak them out to that level?

I had the tools so other than my time and the bedding compound there was no expense. The only tools needed were simple ones for the bedding, a drill press and a hand drill along with an assortment of #'d drill bits. Also a torch for rehardening a couple trigger parts and a couple fine stones to smooth the sear engagement surfaces.

Here's how I modify the gas tube for less violent ejection with standard ammo. With loads using the Lee 312-155 or the GB WFN 150 gr bullet and 4895 the cases are ejected out about like an M1/M14.

SKS GAS TUBE MODIFICATION


SKS rifles are notorious for their violent ejection of fired cases. This may be desirable on the Russian tundra at 20 below but for the reloader trying to find the brass it is intolerable. The following modification will allow the rifle to function reliably yet will deposit the brass into a small area to the right front of the shooter. It also will lessen the hazard to bystanders. Velocity of the ammunition used is not affected.

Use standard 7.62x39 ammunition or the equivalent handload with 123-125 grain bullets when making this modification. The gas system of the SKS allows for more than enough gas port pressure to drive the piston back in the gas tube and cycle the action. This was designed this way to ensure absolute reliable functioning in extreme temperatures and conditions. What this modification does is simply to “vent” the gas after it has imparted enough motion to the piston to cycle the action with out driving it so violently back. As this modification vents the gas rather quickly the use of other than standard ammunition to regulate this cycling may cause malfunctions then when standard ammunition is used.

Attention cast bullet shooters: if you want to shoot really reduced loads with light bullets then regulate it with that. With Lee's 312-155 or heavier bullets I've found functioning to be fine with the conversion made for standard ammo. When medium burning powders (4895, etc.) are used and velocity is in the 1600 fps range I've not had any malfunctions.

To accomplish this modification it will require the following tools:

15 drill bits from #45 (smallest) to #31 (largest)
Center punch
Small round file
Electric drill, cordless or hand drill if power is available at range.

Before going to the range remove the gas tube from the SKS and take out the piston. On each side of the gas tube center punch .22” back from the face of the gas tube. Center punch .35” back from the face of the gas tube directly on top. Now drill each with the #45 drill. You will now have 3 holes, one on each side and one on top. The hole on top will be slightly further back from the ones on the sides. Deburr the inside of the tube with the file lightly and reassemble the piston into the tube and assemble it back onto the rifle. Load up the tools, ammo and rifle and head to the range.

Fire 5 rounds and observe the ejection pattern and how violent the action cycles. Drill out the top hole only using one size drill larger at a time. Test firing with at least 3 rounds between each drilling. You must disassemble the gas tube each time to drill.
NOTE:
I have found on several Russian SKSs that with 2 side holes of #45 size and the top hole of #31 size they will lay the brass into and area of about 3 feet diameter about 6-8 feet to my right front when shooting from a sitting position. The recoil of the rifle is much easier to manage as the action is not functioning nearly so violently. A couple have required the 2 side holes to be enlarged to #40 drill bit size.

Several Chinese SKSs have required an additional hole .3” behind the top one. If the first three holes have not “vented” enough gas then drill this 4th hole. Again starting with the #45 drill bit and going one size larger with a test firing each time.

CAUTION
It is easy to get impatient and drill to much too quick without adequate test firing, DON’T!! You can’t put the metal back. New gas tubes are available at gun shows and out of Shotgun News for a reasonable price. If you’re not sure of your abilities get one first and try it before messing up the original. I have not messed any up using the above method. I have one tube (original Chinese tube that does fit the Russian with minimal fitting) that when used on my favorite Russian will lay the brass almost within arms reach.

[Larry Gibson]

I'll take pictures of the bedding and trigger mods when I get home and post them.

Larry Gibson

[NSP64]

Larry, sounds good I'll keep my eyes pealed.

[Bret4207]

I guess my Yugo 49/59 with the switch to turn off the gas is a peach compared to what Larry went through!

[Larry Gibson]

Not much to go through actually, I've modified numerous SKS's since, pretty simple. They stay semi using my way instead of reverting to single shot (bolt action repeaters). Just depends on what one wants is all.

Larry Gibson

[NSP64]

Made a rubber bumper that will keep bolt carrier from slammin cover. Midway carries them but are out of stock Found a rubber o-ring(metric) at ace hardware that fits around the piston but slides easily. I am loading some 120-140 gr boolits with 2400 & 4227 to see if they will cycle action now. If the o-ring works,but doesn't last, I'll make o-ring from teflon

[NSP64]

Welllll. recoil buffer was good, trigger job worked great o-ring didn't seem to help with 15gr 2400 under a 140 gr PB boolit still didn't work, 17gr 4227 under 115gc boolit almost ejected. Trimmed 3 coils off of main hammer spring, shortened sear/polished, now have takeup then crisp letoff.

[DanM]

Here are a couple of useful links for SKS stuff. The Tech-sights are the bomb if you don't want to put a scope on it. Kivaari does a good reliable trigger job that also gets rid of all that excess take up. I messed up one SKS trigger trying to get it too light. It started doubling on me. I think 3.5-4lbs is about the best you can expect.

http://www.tech-sights.com/
http://www.kivaari.com/

[swabbie]

I have mounted the tech sights and could hit a 12x6 plate at 200 yards with them

this is a miracle for me

next step is kivari's trigger job, and I think I'll order a spare gas tube to try smoke poles mods,ans I'm now castin boolits for the rifle.

still want to acquire a Russian SKS to accompany my norinco "cowboy companion"

thanks for the tips!!

[NSP64]

I have a second resizing die for the 7x39 that I opened up to minimally size my brass( still neck size the same). The new sizer allows the cartridges to fit the chamber snugly.I am off tomorrow,rain forcast(perfect for range session I will slap scope on and see if improvements help. Tried some lee .312 155gc boolits over 4227& 2400 but was getting erratic velocity fluxuations(powder position) and no cycle of action. Back to IMR4895,shot good and cycled action. Will make up new close spaced loads (.2gr changes and shoot for groups.

[kjg]

I had the same problems with my sks and imr 4227 and 2400 went to imr4895 and presto found the load and keeps brass right by right hand and and table, have yet to scope it, had desent results using ideas 172 grain 311413, and lee's 160 grain sks bullet, getting roughly 1" or better at 50 yards gavent gone back to any other yardage to to time and weather restraints here in central georgia been getting some nasty weather. kjg

[swabbie]

Hmmm.I'm gonna try some 2400 loads,but better have a plan for 4895 or H335 if the rifle doesn't cycle..

Was going to pick up some 4895 next week anyway..

would either of you care to part with ur recipe for 4895 using Lee CTL 312-160 boolits without gas checks?

thanks

[kjg]

Swabbie I havent used any unchecked load as of yet, was thinking of trying it with a paper patch but for some reason my pp bullets aren't working as well as others out there as mater of fact I could be sizing them to small and getting gas blow by, but sticking with gas checks untill someting else comes up like a gascheck maker . kjg

[badgeredd]

I'll take pictures of the bedding and trigger mods when I get home and post them.

Larry Gibson

I'm waiting Larry. I will be modifying the gas tube like you said on one SKS. I bought an aftermarket tube just for this purpose. The gun is a early Chinese made from Russian parts.

Also, anyone who may be interested, since I didn't have a mold in the 150-160 range, I lapped out a 311291 Lyman mold that I had bought cheap. It was rusty so I figured no harm would be done. Lapped it to get a .313/.314 diameter on the body and increased the nose to .303. The boolit drops at 178.2 grains with gas check and lube from a babbit mix that is 18 BHN. I only put lube in the lowest lube ring and crimped into the top lube groove. OAL length is 2.135" and it loads, feeds, and functions flawlessly in my rifle. My load is 18.5 grains of IMR 4198 (19.5 started to show pressure signs) and it is checking at an average of 1705 fps. Also tried some AA2015 and IMR 4227 but didn't check velocity or accuarcy (just checking for pressure). The 4198 gave me a 2" group at 50 yds with the original sights (My eyes need something better).