View Full Version : Gas tube vent holes (AK)
My SA 85 has them - others don't. What is their advantage - off gassing an over-gassed system to reduce gun wear?
Any disadvantages?
Thanks
Actually they all have them, just in different locations.
http://aa-ok.com/ak-gas-tube-comparisons.html
Speaking of gas tubes, what prompted the change in the design from a 45degree to a 90 degree gas block?
The AK-47 had/has a vented gas tube, which was changed to a vented gas block in 1959 with the AKM.
The Hungarians actually kept the vented gas tubes design of the older AK-47 and paired it up with the ported gas block. They're the only country that did this purposely.
AK's tend to be "over gassed", it's one of the design characteristics that makes them as reliable as they are. The ports are there to vent excess gas so it doesn't throw it all back into the receiver.
It also helps mitigate the effect of an enlarging gas port due to erosion through use over time.
Speaking of gas tubes, what prompted the change in the design from a 45degree to a 90 degree gas block?
The very first AK-74's had 45* gas ports/blocks, but that was quickly changed to 90* when it was found that they were getting greatly increased shaving of the bullet jacket material.
A 90* gas port also makes it much easier for the port to come through a groove instead of a land.
The very first AK-74's had 45* gas ports/blocks, but that was quickly changed to 90* when it was found that they were getting greatly increased shaving of the bullet jacket material.
A 90* gas port also makes it much easier for the port to come through a groove instead of a land.
OT, how much of of your replies on a given topic can you pull from memory and how much do you have to reference before answering to make sure you remember it correctly?
I can remember the gist of most of the answers you give but not with the specific detail and data you provide. If you are doing all that from recall it really is kinda impressive.
I'm not sure I could do it with a bottle of Ginkgo Biloba on my desk. I even had to look up the name of that memory aid.
Steyr, it's memory, most of my ref. books are boxed up.
Also, other post WWII gas operated military rifles bleed off excess gas as well...
The FN FAL does it both at the gas block (which is adjustable) as well as the gas tube under the handguards.
The M14's piston blocks venting of gas into the atmosphere until it's pushed back by sufficient gas pressure, allowing all excess gas to bleed out. It's "self regulating" and actually works.
Templar: So, do you think the Hungarian system is "better" by keeping both features?
Templar: So, do you think the Hungarian system is "better" by keeping both features?
Not really. It works fine, but so do the straight up AK-47 and later AKM/AK-74 style.
I used a vented Ultimak gas tube for my SLR-106, even though it uses the later vented AKM/AK-74 ported gas block.
No issues, but I doubt I'd have issues with a non ported tube either.
Now, I have, back in the day, used a non ported AKM gas tube on a Chinese rifle, which uses the older non ported gas block....
Rifle functioned 100%, but blew a lot of carbon back into the receiver, and may have caused the bolt carrier group to move back at a higher velocity. Once I realized what was going on, I switched back to a vented gas tube.
Not really. It works fine, but so do the straight up AK-47 and later AKM/AK-74 style.
I used a vented Ultimak gas tube for my SLR-106, even though it uses the later vented AKM/AK-74 ported gas block.
No issues, but I doubt I'd have issues with a non ported tube either.
Now, I have, back in the day, used a non ported AKM gas tube on a Chinese rifle, which uses the older non ported gas block....
Rifle functioned 100%, but blew a lot of carbon back into the receiver, and may have caused the bolt carrier group to move back at a higher velocity. Once I realized what was going on, I switched back to a vented gas tube.
My Arsenal also uses a ported gas block and I run a ported Ultimak with absolutely zero gas issues. The system is so overgassed that I bet you could run it with a guide for the gas piston rather than a gas tube.
There have been some people who purposely installed an unvented gas tube on an unvented gas block in an attempt to make them quieter when suppressed. You're talking some serious back pressure that greatly reduces parts longevity.
My Arsenal also uses a ported gas block and I run a ported Ultimak with absolutely zero gas issues. The system is so overgassed that I bet you could run it with a guide for the gas piston rather than a gas tube.
There have been some people who purposely installed an unvented gas tube on an unvented gas block in an attempt to make them quieter when suppressed. You're talking some serious back pressure that greatly reduces parts longevity.
Most likely you could. Later FAL's only have half of a gas tube. Once you get that initial slap on the piston from the gas, it's enough to keep it moving.
Most likely you could. Later FAL's only have half of a gas tube. Once you get that initial slap on the piston from the gas, it's enough to keep it moving.
Right,
most gas systems only allow 1/4" to 3/4" of travel before venting gas.
I believe in many designs, the primary thing that determines the duration of the power stroke is the length of barrel between the gas port and muzzle.
Right,
most gas systems only allow 1/4" to 3/4" of travel before venting gas.
I believe in many designs, the primary thing that determines the duration of the power stroke is the length of barrel between the gas port and muzzle.
How far does gas travel in an AK compared to an M-1 Garand?
Most likely you could.
I've been meaning to try that for a while. I think I might take one of my spare gas tubes down to my buddies shop and skeletonize it with his milling machine.
Powered by vBulletin® Version 4.2.5 Copyright © 2024 vBulletin Solutions, Inc. All rights reserved.