XCR Gas Valve Setting for Surpluse 7.62x39 Ammo

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Gobc

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I've got an XCR and love it. However, I'm finding that the Czech surplus ammo take a lot of force to extract. I've got my gas valve set to 4. If I reduce it to 3, its very common to get an extraction failure. I've read that the lacquer coating on these shells kind of cooks and acts as an adhesive in the chamber.

Has anybody noticed this on their XCR? Should I be worried about excessive wear and tear on my rifle?

Thanks
 
i've noticed the same thing on mine. The last time I took it out, I used Czech surplus that had been tumbled to remove the coating.

If my valve is at #1, I get the occasional FTE. At #2, it seems to work fine.

How many rds through yours? Past the break-in period ?
 
I think I'm at around 2000 rounds through the rifle now. At setting 4, i get reliable extraction, but as soon as I dial it down, i'll start getting extraction failures.

The break in period was brutal, had tons of faild extractions and jams. Thank god it's over. Rifle works great since. I just have to have it set a the highest gas valve setting.
 
i leave it on setting 4 when shooting surplus. i have a a little over 1000 rounds of 7.62 x 39 now and it works much better than it did when i first got it.
 
With surplus 7.62x39 I find setting four gives the gun way more gas than it needs. Setting four really slams that gas rod back. Setting 3 would work but had a lot of failures due to not enough gas. Since I only shoot surplus 7.62x39 I decided to drill my number 3 hole larger. You will notice a large difference in hole sizes from 4 to 3. I used a 5/64 bit and made the number 3 hole in the gas valve a bit larger.

Now on setting 3 the cases land about 10 to 12 feet away at about 2 o'clock or so. The gun is nice and smooth and it has enough gas to operate without failures.

Do this at your own risk and don't blame me if you don't get the same results.
 
My rifle functions on #2 for the most part, with a few FTE, when the rifle is clean. The failures will occur because of insufficient gas. A few failures to engage the bolt catch on the last round for the same reason; I keep the gas on #3 for operation with the surplus ammo.
It’s a problem is with the low quality and inconsistent ammo and not the rifle.
I pulled 100 rounds of Czech surplus ammo (1968 Lot) apart this is what I found.
Bullet weight (Gr) Min 121.2 Max 122.8 Average 122.2
Powder charge (Gr) Min 21.8 Max 24.6 Average 23.2 (mathematical)
As you can see, there is a large variance in the loads.
This also explains the accuracy issues with this ammo.

But the ammo is cheap and great to plink with.
 
Thanks for all the replies. It seems like were all getting similar results which puts me at east. I might try drilling out the hole as The Giant suggested. But don't worry, if I F it up, I won't blame you.

Thank all.
 
Weird.

I've gradually dialed down all the way to the S setting (So far over 200 rounds ejected reliably, chucks casings about 4 feet). Czech surplus, 1993 production (1200 round crate)

At setting #2 it would chuck the casings about 25 feet to the right.
 
My results are same as Rockenrod. rifle will run a long time with no problems, and then will FTE. Turn gas back to 3 and no problems. Am still waiting for new bolt catch though. Had same results pulling and weighing bullets and powders too, lotsa variance. But, you get what you pay for. And the way this gun goes through :redface: ammo I am glad there is cheap surplus for it.:dancingbanana:
 
First time out with the new conversion kit, it would only cycle properly on setting 4 for the first 200 rounds, the second time out it worked fine on setting 3.
 
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