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Old 11-09-2018, 04:15 PM
nativesniper111 nativesniper111 is offline
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Default Machine Gas Piston

I don't know if anyone has done this and achieve positive results. All M1A that I have seen have op-rod spring pressure against the gas piston when closed. When fired, the op-rod spring strips a new round from the mag and then forces it into the chamber. The end of the op-rod hammers the gas systems piston. What if the piston have a few thousands taken off so that when the bolt is closed, the op-rod and piston don't touch, say there is a .20000 gap? The brass round in the chamber would absorb the shock and not the gas system near the end of the barrel. Hopefully improving accuracy??? I don't know if the government did any of these tests?
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Old 11-09-2018, 04:41 PM
DougS DougS is online now
 
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It would seem that having the piston push on the op rod rather than slamming into the op rod upon firing would be the preferred approach.
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Old 11-09-2018, 04:54 PM
nf1e nf1e is online now
 
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Seeing as the rifle is designed to have the op rod end of travel stopped by the piston tail, I am afraid your rifle would be beat to death with forces on other areas that were not created for such.
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Old 11-10-2018, 03:02 AM
GGaskill GGaskill is offline
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What if the piston have a few thousands taken off so that when the bolt is closed, the op-rod and piston don't touch, say there is a .20000 gap?


Your numbers do not make sense; a few thousandths shortening is not going to leave a .2" gap.
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  #5  
Old 11-10-2018, 06:01 AM
M14 M14 is offline
 
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Quote:
Originally Posted by nativesniper111 View Post
I don't know if anyone has done this and achieve positive results. All M1A that I have seen have op-rod spring pressure against the gas piston when closed. When fired, the op-rod spring strips a new round from the mag and then forces it into the chamber. The end of the op-rod hammers the gas systems piston. What if the piston have a few thousands taken off so that when the bolt is closed, the op-rod and piston don't touch, say there is a .20000 gap? The brass round in the chamber would absorb the shock and not the gas system near the end of the barrel. Hopefully improving accuracy??? I don't know if the government did any of these tests?
There were many test done in regards to the area you mentioned. It was called dwell or timing. The armorers found that taking off a certain amount, ( one, to one and one half turns of the gas cylinder plug, before it got tight) was about ideal for dwell, or the timing of the piston opening the locked bolt.

Most of this was done on the big teams, army and marines. They found that if you took too much off, the piston would smack the op rod so hard, it would break the roller spring clip on the bolts, and the roller would crack.

They also tried taking material off the front of the piston and the back of the gas plug. Both of these caused a smaller gas cylinder inside the piston, which increased pressure and speed of piston travel, thereby negatively affecting dwell. There were also worries about the hardness of the tail of the piston and taking material off of it and getting peening. But IIRC, the piston is hardened through and through.....but I'm old, so who knows if I recall anything correctly..

Bottom line here, if you are thinking of changing something in the system, don't. It's all been tried before and found it's best to leave it just as it was designed by that genius Canuck guy..... and his cohort, Mr. White.

Now that is an interesting story.....the White gas cut-off system..... Poor guy had more trouble getting something through the red tape gov system than I have. Check it out if you want to hear a sad story and see just how bad some politicians can screw a guy in the military supply system.

Thank God it isn't that bad now...Ha ha ha ha....yeah, right!
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Old 11-12-2018, 12:01 PM
wrwindsor wrwindsor is offline
 
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Quote:
Originally Posted by nativesniper111 View Post
I don't know if anyone has done this and achieve positive results. All M1A that I have seen have op-rod spring pressure against the gas piston when closed. When fired, the op-rod spring strips a new round from the mag and then forces it into the chamber. The end of the op-rod hammers the gas systems piston. What if the piston have a few thousands taken off so that when the bolt is closed, the op-rod and piston don't touch, say there is a .20000 gap? The brass round in the chamber would absorb the shock and not the gas system near the end of the barrel. Hopefully improving accuracy??? I don't know if the government did any of these tests?
It would reduce your accuracy -- any inconsistency affects accuracy.

You have that gap (assuming you meant something more like .020" or .002") and the piston is effectively free-floating somewhere between "0" and .020/.002. You have no way of controlling the distance the piston travels before engaging the oprod and you have no idea what speed it is traveling when they make contact.

I asked a similar question some time ago. Short answer: "it's designed to be in constant contact in 'bolt closed' position."
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Old 11-12-2018, 12:44 PM
Ted Brown Ted Brown is offline
 
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Actually, it's not uncommon for some match armorers to make adjustments to the dwell in an M14. I have found the best way is to remove material from the rear end of the gas piston allowing the operating rod to move forward, which lengthens dwell timing. Alteration to parts inside the gas cylinder, like shortening the front of the piston or the rear of the gas plug effect the volume of expanding gasses in the system which can effect functioning and accuracy. It's important to not allow the operating rod to contact the bolt roller when at rest or to create a gap between the op rod and rear of the piston. These things are detrimental to accuracy.
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