Yugo SKS - bore opening under rear leaf, WHY??!!


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judaspriest
August 19, 2007, 07:47 PM
Hi all,

A surprising finding when replacing the rear sight of a Yugo SKS - there is an opening in the bore there! It seems totally bizarre - what functional purpose can it possibly serve? It also explains the annoying exhaust at every shot that I smelled. Needless to say, it was quite dirty there as it is impossible to get to during the normal course of cleaning.

I am considering having it sealed up somehow, but thought I'd check with the experts first to see if it serves some obscure purpose. Any ideas?

Many thanks,

JP

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DMK
August 19, 2007, 07:49 PM
It's not opening into the bore. It's opening into the tube above the bore. This tube holds the oprod and spring.

In front of the oprod is a piston and in front of that is a gas valve. Under the gas valve is a very small hole that does go into the bore. When the bullet passes this hole, gas from the burning gunpowder goes up into the gas tube pushes the piston back, the piston pushes the oprod back, and the oprod pushes the bolt carrier back. The bolt carrier pulls the bolt up (unlocking it) and back. On it's way back, the bolt cocks the hammer for the next shot. The recoil spring behind the bolt carrier pushes the back carrier forward, which pushes the bolt forward, which pushes the next round in the mag into the chamber. Pull the trigger and it all happens over again.

BTW, when the gas piston gets all the way to the rear, the gas in the gas tube is vented via several small holes in the gas tube. These are under the top handguard.

As to why that hole is there? I don't know. Maybe it's there as a way to extract a broken oprod spring. It's covered by the flat rear sight spring when the sight assembly is together, so dust and dirt can't get in there.

jpwilly
August 19, 2007, 07:54 PM
Yea it's certainly not under the same pressure as the bore your you wouldn't have those sights any more! BTW cleaning it is optional!

judaspriest
August 19, 2007, 09:58 PM
I see. So, I take it trying to seal it up won't be wise, will it? :)

Thanks,

JP

DiN_BLiX
August 20, 2007, 09:46 AM
A surprising finding when replacing the rear sight of a Yugo SKS - there is an opening in the bore there!

Im confused, can you post a pic?

dstorm1911
August 20, 2007, 11:01 AM
actually cleaning it is needed unless ya are 100% totally absolutally positive no corrosive primers have been used in your bargain Russian commercial ammo.......

Ya might be getting excessive gas blow by if the gas piston is worn, the op rod actually only moves about 10 mm on an SKS (thats why they are a short stroke gas system as opposed to the AK where the gas piston is actually attached to the bolt carrier and will follow it through the full cycle) most of the Yugo SKS that saw actual use often didn't see any cleaning even if the bore was cleaned the gas system wasn't which resulted in corrosion eating up the edges of gas pistons etc........ ANY place powder gases can reach on a weapon ya need to clean

Correia
August 20, 2007, 12:32 PM
It is the same on an AK47. Pull your rear sight and sight spring off and it is open into the gas system. It is totally normal, and is no big deal.

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