I read the idea that some how having the GCL tight against the shoulder of the barrel removes the stress from the barrel threads. I have to ask; HOW????
It's the screw threads that force the GCL against the barrel shoulder.
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I read the idea that some how having the GCL tight against the shoulder of the barrel removes the stress from the barrel threads. I have to ask; HOW????
It's the screw threads that force the GCL against the barrel shoulder.
The threads on the barrel are very soft. The play in the threads causes them to get hammered when firing, which will eventually wear them out. If the gas lock/thread play is eliminated no more hammering. A tightly fitted gas cylinder also reduces the stress on the threads.
How many rifles have you seen with the barrel treads worn out from GC movement?
I had a S/A field grade with worn barrel threads. With the gas cylinder lock and gas cylinder lock screw tight, I could slightly move the gas cylinder and gas lock front and rear. I tried several gas cylinder locks with no change. I slightly flatten all the thread on the barrel and installed a NOS gas lock. The gas cylinder didn't move after that.Quote:
Originally Posted by precision32
I've seen a lot of barrels with worn threads, although I admit I've never done any kind of scientific analysis as to why. Here is an old post from Jouster by Gus Fisher. He claims to have seen thread wear that he blames on gas locks.Quote:
Originally Posted by precision32
http://www.jouster.com/forums/showth...Gas-Lock/page2
"Even though I know of no hard and fast evidence or studies on fitting GC locks;"
Nothing is going to change the recoil impulse. The energy is going to work on the threads no matter what you do.
Jak, how do you prove that the wear you see is from the threads not being tight? How do you tell the wear from normal tolerance of the treads?
e=mv^2
Sort of the way a hammer works.
I know what you're saying. But if the threads can resist E, than they will not be damaged. I have a 100 stone anvil (225#) that you can bounce a 3# sledge off of all day with out damage. ;)
I don't know, it's just another thing that we can busy ourselves with. The fact that the barrel and the gas lock have mating tapers built into them makes it look like they were designed to -mate. I'm not sure of the thread spec on the gas lock and barrel but most feel way looser than a 3a/3b fit. On the other hand try screwing a FAL barrel into a receiver. It's almost an interference fit. Now add on a loose fitting gas cylinder and you not only have frictional wear on all the surfaces but gases escaping which will erode the surfaces. If you manage to get a snug fit on the gas lock taper it will keep the hot gases away from the barrel threads. Messing about with guns is a hobby, so why not take a little extra time and go for that perfect fit and finish.
Shuff goes a little bit extra on these things. He machines his gas pads with an extra couple of thou of interference. You need a dead blow hammer to get the gas cylinder on but they ain't moving and they ain't leaking.
I draw the line at bolt lapping though.
Normal thread tolerance allow for a very slight movement of the gas lock on the barrel threads which is normal for any type of nut and bolt arrangement. On my rifle I was talking about there was front to rear movement that you can not only feel but see. Just screwing and unscrewing the gas lock on to the barrel a thousand times would not cause the threads to wear out. The barrel threads were damaged by the threads of an improperly tightened gas lock slamming back and forth into the barrel threads every time the rifle was fired. All my other garands show no front to rear movement of the gas cylinder/gas lock when properly tightened down. That includes several WWII garands with original barrels that obviously had several thousand rounds fired through them.Quote:
Originally Posted by precision32