[Roc Rat]

I put this to the M 14 Forum and got no feedback,,, so I'm gonna put it to you guys.
Some time back I decided to try to unitize my gas cylinder on my Springfield M1A. I took the gun apart to that point,, no barrel removal, just the front sight/FH assembly, gas plug, piston, the gas cylinder lock and tapped the cylinder off. I have had it apart for several months and picked up a NOS front bbl band,, USGI which was much tighter,, I decided to try it instead of going the unitizing route. I tapped the gas cylinder back on and attempted to tighten the lock. From the barrel end it bottomed out at the eleven oclock position, and I tightened it down into positiion. Thing is, the piston and plug would not go together,, again, from the bbl end,, the top of the hole on the lock where the piston slides into the cylinder was interfearing with the bore of the cylinder. I polished the edge to the point that there is no metal to interfear with the piston or plug. The plug will now go in and turn, but it is hard. The piston will go into the cylinder,, past the lock, but binds at the mouth and will go no further. If I loosen the lock, the cylinder and plug drop right in,, smooth as silk. It almost seems as if the tight lock is torquing the cylinder assembly. Smith sells shims, but I am wondering if the lock's threads can be damaged after it, the lock, is removed. I know that bbl threads are designed to "crush" into a lock down position,,, I'm wondering if this is the case with the lock. I can't remember where the lock turned free when I diassembled,, The lock seems to go out of allignment when it makes that last bit of rotation into position. Any help would be appreciated,, I want my M1A back!!!!!

 

[TARGSHOOT]

just a shot here, make sure to ck the mating surfaces on both parts, maybe one of them are cut/ground on an angle causing the cylinder or lock to distort when torqued down......just a thought

 

[fjruple]

Roc Rat--

I have found that sometimes when mating GI NOS parts to after barrel that the gas cylinder will slide back further then expected. (Shoulder on barrel for gas cylinder is out spec.) This will cause a number of problems first is the gas port in the barrel will misalign with the gas cylinder and second the cylinder lock will be in the condition that you described. Placing a shim or shims between the shoulder of the barrel and front barrel band will solve the problem. I have seen the number of shims used to vary from barrel to barrel. Key is making sure the gas port aligns with the gas cylinder. You should also be using a gas cylinder wench to put the gas cylinder lock on. You can very easily put it out of alignment. I hope that helps.

--fjruple

 

[Roc Rat]

fjruple,,Thats about what it was,, I had gotten the NOS barrel band, I checked it against the SA one and found that it was thicker. This was causing the lock to come into contact with the cylinder too soon,, at 11:00. By the time it got to 6:00 it was too tight and was shifting in the threads, causing the mis-allignment between the lock and cylinder bores. I made a shim,, approx .022,, and put it between the barrel shoulder and bbl band. The lock made contact at 5:30 and tightened at 6:00. All is well in Muddville,, Thanks RR