View Full Version : Carbine vs Rifle length gas tube?
I hear the rifle and mid length gas tubes are supposedly more reliable -- do you have an opinion?
Also, I was just thinking since a carbines gas tube is shorter that it may blow less fouling into the receiver, anyone know about that? :confused:
Maybe whichever has more barrel after hole gets more fouling into the receiver after the bullet passes by?
Rob_s wrote:
The midlength gas system of the N4 gives you a lighter recoil pulse, less wear on the internal parts, and the possibility of more railed real-estate should one choose to go that route but maintain the stock FSB.
Well guys I found some Rob_s musings that shed light as to why a rifle lenght or mid length gas system is preferred by some.
But I am still wondering if anyone knows if one or the other spits more fouling into the receiver?:confused:
thx for looking, regards
mndfusion
I could be wrong, but the issues with the carbine system were higher pressures created by the gas port being closer to the chamber causing higher cycle rates and possible more wear and tear on your rifle. By moving the gas port out to say mid length you gained a slightly lower cycle rate and pressure on the system plus a better sight raduis. So to answer your question higher pressure/cycle rate would lead me to believe there is more gas entering the chamber to cycle the weapon. So more gas = more fouling. Maybe......
I
So to answer your question higher pressure/cycle rate would lead me to believe there is more gas entering the chamber to cycle the weapon. So more gas = more fouling. Maybe......
Not really. My carbeans run no dirtier than my rifles. Some run cleaner actually.
The reliability issues don't come from fouling.
So i would be safe by saing that the added pressure of a carbine system does not increase fouling, but the increased cycle rates, due to increased pressures, are where the reliability issues stem from.
So i would be safe by saing that the added pressure of a carbine system does not increase fouling, but the increased cycle rates, due to increased pressures, are where the reliability issues stem from.
I understand that "increased cycle rates, due to increased pressures, are where the reliability issues stem from" thx for posting it though.:D
but I'm still not sure on which one blows more fouling into the reviver (not that it has to do with reliability.)
It seems to me that the barrel with the longest distance between gas port and muzzle would blow the most gas into the receiver. It just seems like a logical conclusion, b/c after the bullet passes by the gas port hole gases will continually flow through the port until the bullet exits the barrel.:confused:
It seems to me that the barrel with the longest distance between gas port and muzzle would blow the most gas into the receiver. It just seems like a logical conclusion, b/c after the bullet passes by the gas port hole gases will continually flow through the port until the bullet exits the barrel.:confused:
Not necessarily true. You see.... Port sizes are different depending on barrel length and gas system length.
Generally the shorter the barrel after the port, the larger the port will be to make up for the reduced dwell time.
They all obviously blow at least some amount into the receiver during cycling. I don't know that there is really any measureable difference between one and the other.
It would seem simply from a volume standpoint that the longer gas tubes of the midlength and rifle length gas systems would, maybe, possibly, allow some additional "fouling" into the receiver.
I feel this would be more of an ammunition issue than a gas system length issue. As in if you shoot shitty dirty ammo, expect to have to keep your rifle more heavily lubed to ensure reliable operation.
-RD62
I feel this would be more of an ammunition issue than a gas system length issue. As in if you shoot shitty dirty ammo, expect to have to keep your rifle more heavily lubed to ensure reliable operation.
-RD62
I hear you there, its like a night and day difference when I use premium powder in my handloads. I like Hogdon extreme extruded powder. The Hogdon powder not only burns cleaner (more of a very light gray residue, never black) but there's less flash, smoke and smell.
I thought at 1st that the longer gas tube would push more gas into the receiver. But then I took into account that the gas port on a 20 in. is closer to the end of the brl, only a few inces from the muzzle. But a 16 in Carbine However has maybe 10 in. of barrel after the gas port, and no doubt there is a crapload of pressure in the brl that whole time pushing through the port.
demigod did point out that "Port sizes are different depending on barrel length and gas system length." but I'm not sure that would level out the carbon blown through into the receiver:confused:.
thanks everyone!
I have no idea how anyone measures fouling with any kind of objectivity.
Also, re: port sizes, that pressure has to go somewhere. If the rest of the system is sealed (which obviously it's not since eventually the bullet leaves the barrel and the case is ejected) then a smaller post size just gets you a faster gas stream. Think of the strip mines in Pale Rider when the character played by the Penn brother is explaining to the girl how the pipes work.
RogerinTPA
08-30-08, 11:01
Bernoulli's Principle. Smaller the hole, gas (or Liquid) is compressed, faster the velocity.;)
Most would consider full length most reliable, Midlength second and carbine length least.
I have no idea how anyone measures fouling with any kind of objectivity.
That.... and I don't find one gas system or barrel length to run significantly cleaner than another. It's not even an issue to worry about at all.
Fouling doesn't shut ARs down. I've seen some crazy dirty guns that run flawlessly.... they must have been relubed periodically.
I have no idea how anyone measures fouling with any kind of objectivity.
I do, just get 100 rifles and 100 carbines then fire them until they choke, dry up, and see which one wins.
Some is getting through here. Lemme add some more.
You will not get much difference in fouling as the gas that is used is fitting into a fixed space. The fixed space is larger depending on the system but the port size is there to accomodate this to allow for the gas to fill that space quicker or slower depending on the tube length. Once again though it is a fized space...IE a cylinder......when the cylinder is full it is full. There isn't an open valve that allows a "continuous" flow of gas - thereby increase the amount of fouling.
The primary issue is that the BCG wants to travel backwards (thereby unlocking the bolt) before the case pressure has dropped. that is why the carbines had a tendency to jam up. They would regularly have the extractor slip off the case and FTE and then feed a live right in line and jam. The solution was to make the extractor grab HARDER....much HARDER.....hence crane o-rings, heavier extractor springs and harder rubber extractor spring inserts.
In middies and rifle length systems, the case pressure has had a chance to drop due to the longer dwell time (port to muzzle distance). As a result, they do not need the tougher springs on the extractor.
Boltgun
Here's on thing I have found. On a 20 inch AR I did notice an undeniable lack of bolt carbon in one setting:
The rifle was a 20" HBAR. The ammo was the original PRIV/Wolf M-193. The first wave of this stuff... the problematic stuff. Anyway, that ammo had a propellant that burned TOO FAST. Thus, it'd choke/shortstroke on most rifle systems since most of the powder charge had burnt up before the bullet passed the gas port.
In that extreme example, the length of the rifle gas system allowed more of the powder charge to be burnt up, and thus fouling was noticeably less in the bolt group.
I think the amount of fouling would be MUCH more dependent on the kind of powder than the length of barrel/gas system.
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