I have seen short pigtail gas tubes for sale, but never seen one for a rifle length gas system. Does anyone make these?
Thanks
Thanks
Pigtail gas tube
- Thread starter larryh128
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i've not seen one either. i thought the concept was to make shorter barreled platforms perform more reliably, mimicking a longer rifle function (delaying or altering bolt timing). curious
- Nov 3, 2010
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I thought they were supposed to mimic carbine length or longer. I have one in my junk box that was supposed to tame the gas on a pistol length 7.62x39 but it was so big it didn’t fit under handguard so I swapped to a standard one. Luckily I don’t have any overgassing issues anyway.
My thought was to help delay the bolt opening on a creedmoor. Got a heavy buffer, extra power spring, adj gas block but looking for a bit more lock up time. Suggestions?
- Nov 3, 2010
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Suggestions would depend on what your needing it to do as far as dwell time. A more adjustable gas block, extending your gas length, modifying your gas port are all options but may not be cost effective for the return your looking for. The biggest way to get a chime in for help is to define the problem or perceived problem and what your hopes are in reference to a solution.
I can adjust the gas to zero but I'm looking for a few mill-seconds more dwell time to help brass survive a few more loadings.
- Nov 3, 2010
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Totally adjustable by turning in the screw. I can go from bolt action to slamming.
- Nov 3, 2010
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Maybe a buffer setup with more adjustability or a hydraulic buffer. I’d lean towards more weight on the recoil side if changed recoil isn’t an issue to you. What is your setup now
I tried a hydraulic buffer and ended up with a Tubb flat wire spring and a 9 oz buffer. Only option now as I see it is to lengthen the gas tube. Right now the rifle runs good with the load I'm using but I'm always looking for more horsepower.
Pigtail gas tubes are voodoo. They don't increase dwell time, so all they are is three inches of more gas tube volume that is worthless to anyone who isn't making $ selling that snake oil.
I guess I need to be educated on +2, +3 gas systems, I thought (maybe incorrectly) that they had the gas hole further down the barrel? My thought was a longer gas tube would accomplish the same thing.
I freely admit that I could be wrong here, but I think that the reason that longer gas systems work while longer (pigtail) gas tubes don't work is that the longer system offers lower gas pressure at the port than would the shorter system with the pigtail tube.
Think about it this way. You basically have two values to work with, pressure and flow (volume). You can restrict flow (volume), but you can't restrict pressure. Pressure has to be regulated. At a given pressure (constant), and a given flow (volume), it doesn't matter how long the tube is. In other words, if you have 5' of ½" pipe with 50# of pressure on it, will making the pipe 10' long change either the flow rate or the pressure? The answer is NO.
thinking out loud: what about altering the size of the port in an effort to change velocity or perhaps pressure? but i guess that's what an adjustable gas port should do. is there any chance that your current gas port is not correct in dimension? you might be able to check with a pin gauge.
if you're reloading i guess you could always slow the projectile down, using different powder formulations?
what about a different weight bcg?
i've also read that linear compensators can inc dwell
if you're reloading i guess you could always slow the projectile down, using different powder formulations?
what about a different weight bcg?
i've also read that linear compensators can inc dwell
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No, it's been an issue with a lot of what I would call higher pressure cartridges. No issues with a 308 and go to a 6.5 C and there are issues if you want to shoot anything but lolly pop rounds. I'm not trying to shoot 28" bolt gun speeds but I would like to get a bit c;loser.
I fully understand that pressure is pressure but with that thought, how is moving the gas hole further down the barrel doing anything but slowing the pressure build up by a mili second?
my understanding is that the gas that impinges is developed and contained while the projectile is still in the barrel..if the port is too close to the projectile's exit then there would not be enough time for appropriate impingement.
The pressure peaks about 2" from the case mouth, then is dropping dramatically as the bullet goes down the barrel. IIRC an M4 "carbine" gas port is in the vicinity of 30-40ksi port pressure while a "rifle" system is more like 20-25ksi. Port pressure way out on the end of the barrel on an M1 Garand is closer to 10-15ksi.
The only thing the pig tail gas tube does is buy you the difference in time it takes 20-40ksi gas to vent through the port and pressure wave an extra 3 inches or whatever it is. The difference is much less dramatic than what moving the port 3" down the barrel does. The air/gas that is resting in the tube before firing is compressible, so it does slow things down slightly, but my opinion/guess is that that compressibility "spring" is bottomed out real quick and becomes non-compressible in very short order-- like nearly negligible.
This. The claims for the pigtail gas tubes were that they increased dwell time, which is bs and snake oil marketing to people who don't know what dwell time is. There's good reason they've mostly disappeared from the market; don't waste your money.
