Why does a gas trap system lead to more fouling than a gas port?
Posted by SAM5TER5@reddit | ForgottenWeapons | View on Reddit | 5 comments
I’ve heard it mentioned a couple times that gas traps rifles such as the original M1 Garand and Bang rifle are bad due to higher amounts of fouling. Is there a particular reason why this was the case, or is that just the nature of the very small number of designs that tried it? Could it be improved upon, or is it inherently dirtier?
CxsChaos@reddit
Could be that having the gas tube located at the muzzle leads to more unburnt powder and carbon going into the gas system. The larger diameter gas tube is also a possibility. I don't think that this design could be improved because of the inherent drawbacks a gas trap system.
bmbreath@reddit
Wouldn't the port closer to the muzzle be more burned than that which is closer to the actual action itself?
As in, wouldn't the combustion be more complete, aka, cleaner at the terminal end?
GrahminRadarin@reddit
Yes, the combustion would be cleaner, but there's more crud than a gas port because the trap is in front of the muzzle. When the unburned material is traveling down the barrel, it will come out the end of the barrel and into the gas trap. If you have a gas port, the unburned material does not travel out the side of the barrel into the port because there's nothing to make it turn that way. If there was crud going into the gas port, then the gas trap would get less of it, but because of the inherent physics of the gun, there is very little going into the gas port in the first place.
dontdoxmebro@reddit
Gas traps use more gases at lower temperatures and pressures than gas piston rifles to cycle the action. The increased volume of cooler gases leaded to faster carbon buildup. The G41 in particular had significant issues with fouling. Gas trap weapons can seem to be under gassed, and they don’t have an easy way to add an “adverse” gas setting.
However, the original gas trap Garand mostly failed because the whole muzzle device was a little bit fragile and had several issues such as not really holding the front sight 100% securely, mounting bayonets 100% securely, and not really staying on the rifle 100% securely. The design was asking two small screws to do a lot of work, and since they were doing separate jobs, if either failed, the gun failed. While fouling and foreign material ingress were also issues with the gas trap Garands, the fact that the gas trap could wiggle loose, then be blown off the rifle when fired, was really the major flaw, which was pointed out by Ian in his video on the gas trap Garand. The fouling did mean that the muzzle device had to be more frequently taken apart and cleaned, which increased the risk that the gun would not be assembled back together correctly or that the little screws would back out, increasing the risk of a sudden muzzle device removal. The muzzle device for the gas piston Garand was significantly more securely attached to the rifle, had a better, adjustable front sight, and zero overworked little screws. It was also significantly less likely to be damaged by using the bayonet. (The Garand had one major advantage over the Johnson rifle, other than being adopted first and Garand having worked with Springfield, and that was that the Johnson rifle was simply a terrible bayonet host.)
Some gas trap Garands served throughout the war, occasionally showing up in pictures where they should not have been. The design did work. It just wasn’t as good as the replacement, and the 7th round stoppage was a far more significant issue for the first few batches of mass produced Garands.
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