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Back out with the Lewis.....fizzled again. Even with all the gas leaks fixed, it did the same thing. 4-6 rnds and stop with the cocking handle 1 1/2" short of the sear. And, kinda stuck there, wouldnt move either way without some level of force. I had to use the end of a bigger hammer handle to push it. Once it moved a short distance, all was freed up. While it was in its stuck position, I wiggled the drum to see if that would free it.....nope. I am going to make a gasket for the gas tube connection with something. I am beginning to think the problem is in the feeding. Next time I am going to try much new ammo, I have some 1964 surplus. If not that, I will look in into the feeding system. Would seem odd if that was the problem with 4 different drums.

PJH
 

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OK, here's a bit of a guess. Look at the Feed Operating Arm and the Feed Stud (on rear of Bolt). I suspect that the stud is not staying in the track on the Feed Arm when the bolt comes back. That's the only thing I can think of that would cause a lock-up at that particular position.
If the Feed Arm is warped or bent, then the Stud could bind against the Feed Arm if it comes out of the track. The also would explain why when you bumped the bolt forward enough for the Stud to be back in it's track, things appeared OK.

I hope that helps.
Andrew
 

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10-4........ I have examined the sequence of events of these parts several times The slot the stud on the rear of the bolt slides forward in intersects a curved channel in the top rear of the receiver. A small lug on the back end of the curved feeding arm (???) rides in that channel. There is distinct evidence that the lug has been striking both sides of that slot hard enough to peen both the lug and the slot. I cannot detect a bending of any part. I could duplicate this event by hand. In a sub assembly, the curved feeding arm came to a complete stop before the bolt could get back to the sear. Annnnddd.......so, since I can see peening, which cant be good, and the lug catching in the slot will definitely stop the feeding arm before it gets to the end of the channel, I filed a very slight angle on all the parts involved, ie; those surfaces that already showed signs of peening. This also removed metal that was flared upward. I can no longer get it to catch like it was when operating it by hand. Hopefully in the field today.

PJH
 

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Phil - to that end, look atthe over travel issue - My Op rod had a little cork dooddad in the end of the op rod that hit the stock / over travel stop. the cork finally "evaporated" and my gun would do the same thing - it sticks the bolt becasue the bolt stud over travels and comes out of the track in the back. to test the theory, I went to ACE hardware, got a small rubber stopper from the "cool little stuff you did not know they made bins" , sanded/ground it down to a conical shape on the small end and stuck it in the end of my op rod. Retained through an existing screw hole in the OP rod (maybe intended for that ?) This seemed to solve my problem. More tension on the spring did not seem to work.
 

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I was fascinated with this discussion and was wondering if you tried the the rubber buffer/spacer in the Op rod.
What did it do?
 

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I noted the hole in the end of the LEWIS op-rod.
Reading about it, there was a conical wound flat (clock type) spring that was fitted into the aircraft guns.
It acted as a buffer.
I didn't find an explanation as to why it was only used in the aircraft guns.
Perhaps the rigid mounting and the "D" grip in place of the stock?
 

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Im thinking your trouble lays under the rear end cover. Slide that backwards carefully and look at the springs that set the arm levers. Check for mis alignment, mauling, and other perversities. And yes, i recieved your barrel and it helped a great deal, thank you.
 

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I found images showing the horizontal volute spring I was trying to describe.
The image comes from an aircraft armament traing manual from the late 1920's.
Part # 52 and 53 in the plate.

99748


This drawing may also be helpful

99749
 
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