r/canadaguns • u/starw24-ps4 • May 01 '26

Fix my gun SKS Undergassing Fixes?

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I have received an sks that has a barrel which has been cut and crowned down to 18.6”. The owner told me it has been short cycling, which from my research says could be due to either the gas system being loose or more likely due to the dwell time in the barrel now being shorter.

I am going to bring this gun to the range with a bunch of spare parts for a day to start troubleshooting it, and see if I can get it to work. My current fix steps are below, am I missing anything? Do you guys have any tips to help this cycle? 18.6 Sks pictured with a cherrywood stock for attention.

  1. Try it as normal, if it doesn’t work then -

  2. Swap gas tube to second one

  3. Tape front end of gas tube in case of gas loss

  4. Swap long gas pistons

  5. Swap short gas piston and spring

  6. Swap recoil spring

  7. Swap bolt and carrier

  8. Try a detachable mag and new ammo?

Worst case if it still doesn’t run, I may look into either getting a lighter recoil spring or cutting down an extra one to see if that lightens the bolt. Thanks!

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u/therowdyirishman May 01 '26

You seem like quite a thorough gent, so hopefully this isn't irrelevant advice due to you already taking these measures. I would start by doing a through inspection of the gas system. Check to insure the gas port isn't obstructed by heavy fouling. Check out the gas tube to see if heavy fouling or corrosion are restricting movement of the primary piston. Check the same for the short piston and ensure the retention lever is in the correct position. After that I'd give the bolt and guide rails a look to check for wear that indicates an unhealthy amount of friction. Lastly I'd ensure the recoil spring is installed in the correct orientation.

The SKS tends to be quite reliable and receives ample gas. Given this I'm leaning towards the prior owner being a bozo rather than it being a genuine dwell time issue. If I were you I'd try all of the above prior to investing in spare parts. Good luck and give us an update with what you learn after range testing. You can also try posting on r/SKS if you wish.

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u/starw24-ps4 May 01 '26

Thank you for the reply sir! After the comments on here I’m going to give the gas port a second look, I just eyeballed it and guessed it was fine since I didn’t see anything. Will be giving it a once over cleaning.

Spare parts wise I have another sks so they’re easy to swap in a few seconds, but yeah I’ll give those tips a shot before I start gutting the old girl. Thank you!