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armandolo
12-11-2008, 8:48 AM
There are two choices for a 7.62mm AK type rifle.

Choice 1 (AKM) - 45 degree gas chamber and a slant compensator
Choice 2 (AK103) - 90 degree gas chamber and a 74 style muzzle break

I understand that the slant compensator is to correct the muzzle climb during auto fire, so the muzzle break upgrade found on 103 may actually help with recoil and accuracy during semi-auto fire.

I do not understand why the AKM gas chamber was changed. Does 90 degree chamber have any advantages? Performance, maintenance etc. And lets say you had a choice of 7.62mm rifle which option would you pick?

Thanks

Booshanky
12-11-2008, 9:08 AM
I can't imagine the shape of the gas chamber plays that much of a role in the action of the firearm.

hybridatsun350
12-11-2008, 9:57 AM
7.62 AK's didn't originally use the 90* gas block. The switch to the 90* gas block was done on the AK-74 because they had a problem with some of the bullet jacket shearing off in the barrel. I don't know of any advantage to having a 90* gas block on a rifle chambered in 7.62.

jumbopanda
12-11-2008, 9:59 AM
7.62 AK's didn't use the 90* gas block. The switch to the 90* gas block was done on the AK-74 because they wanted to reduce the chance of the bullet shearing in the barrel or something like that.

+1

It doesn't really make a difference for a 7.62x39. The 45 degree one was originally designed so that you could poke a brush in there and clean the gas port, but honestly how many people have ever done that?

M. Sage
12-11-2008, 10:01 AM
7.62 AK's didn't use the 90* gas block. The switch to the 90* gas block was done on the AK-74 because they wanted to reduce the chance of the bullet shearing in the barrel or something like that.

The 103 does use the 90* block. And it is a 7.62 rifle.

hybridatsun350
12-11-2008, 10:12 AM
The 103 does use the 90* block. And it is a 7.62 rifle.

I know. I changed my wording almost immediately after posting my response.

armandolo
12-11-2008, 10:40 AM
Thanks for the mention of the Bullet Shear. But now I wonder if I sould put a 45* one on Saiga? Any comments.

I found this on tantals website:

" IMAGE 6: This is the 90-degree gas block which was introduced into Russian AK-74 production in about 1977. This design change corrected a problem associated with the higher velocity of the 5,45mm used with a slant gas vent and it's associated angled gas block. Going to a 90-degree gas vent eliminated "bullet shear" and the new gas block made cleaning the vent much easier.
Earlier Russian AK-74's had a 45-degree angle gas vent on the barrel and used an AKM-type angled gas block. It was found that the angled gas vent hole on the bore (and therefore longer groove) was causing the bullet to shear off metal as it passed this point in the barrel. This was something never encountered in the slower moving AKM bullet. Going to a 90-degree drilled gas vent, and drilling it in the groove instead of the land. corrected this and also was said to increase accuracy. The Russians designed a new gas block to accompany the new hole, which made cleaning out the vent easier."

skateboarder74
12-11-2008, 10:41 AM
It does not matter at all.

kalieracer
12-11-2008, 11:13 AM
Thanks for the mention of the Bullet Shear. But now I wonder if I sould put a 45* one on Saiga? Any comments.

I found this on tantals website:

" IMAGE 6: This is the 90-degree gas block which was introduced into Russian AK-74 production in about 1977. This design change corrected a problem associated with the higher velocity of the 5,45mm used with a slant gas vent and it's associated angled gas block. Going to a 90-degree gas vent eliminated "bullet shear" and the new gas block made cleaning the vent much easier.
Earlier Russian AK-74's had a 45-degree angle gas vent on the barrel and used an AKM-type angled gas block. It was found that the angled gas vent hole on the bore (and therefore longer groove) was causing the bullet to shear off metal as it passed this point in the barrel. This was something never encountered in the slower moving AKM bullet. Going to a 90-degree drilled gas vent, and drilling it in the groove instead of the land. corrected this and also was said to increase accuracy. The Russians designed a new gas block to accompany the new hole, which made cleaning out the vent easier."

5.45 / 5.56 / 7.62 = 90 - degree works just fine

7.62 = 45 degree works just fine

armandolo
12-11-2008, 12:06 PM
5.45 / 5.56 / 7.62 = 90 - degree works just fine

7.62 = 45 degree works just fine


What I mean though is if Saiga is drilled for 90*, whouldn't the 45* make it somewhat prone to problems.

Are there any converted Saiga owners who put a 45* chamber?

jumbopanda
12-11-2008, 1:09 PM
What I mean though is if Saiga is drilled for 90*, whouldn't the 45* make it somewhat prone to problems.

Are there any converted Saiga owners who put a 45* chamber?

Err, why would you want to replace the gas block anyway?

hybridatsun350
12-11-2008, 1:10 PM
Basically, what it comes down to is the 90* works on any caliber rifle. That is probably why all AK-100 series weapons have the 90* block. It is cheaper to manufacture them all the same even though the 7.62 doesn't require the 90* gas block.

armandolo
12-11-2008, 1:53 PM
Err, why would you want to replace the gas block anyway?


Its going to be replaced anyway to allow for upper/lower handguard install.