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/ThePoeticJester May 01 '26

I think TNA or another gunshop started making newly made gas pistons, maybe the tighter fit there might help? Otherwise you could open the gas port slightly more (hell it'll errode over use to be more open lol) could try stripping it all down and polishing all contact surfaces along the gas system, maybe less friction would help

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u/starw24-ps4 May 01 '26

Yeah the gas mating surfaces is where I was worried, this gun is a mix and match of different factories so there is a small gap in the gas tube where it attaches to the port.

Will polish before I head out thank you!