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Hi Peter; Do you have any tricks in your bag on tighting the gas tube on a
L1A1? When the flats are in the correct position for the retaining pin the gas tube is not tight in the gas block, thus loss of gas pressure. What would you do in this situation.
Thanks Jeff Hamerstone
Excerpt from EMER D 118, Issue 10, Jan 87, Table 4, Page 21.
Gas Cylinder
g. rotational movement is not required but is to be accepted providing that the gas cylinder does not cover the vent to a degree that weapon fuctioning is affected.
Max width of gas slot:
Top: 0.180 in.
Bottom: 0.160 in.
Length of gas slot:
Max: 0.260 in.
Min: 0.240 in.
NZ Armourers would normally file the end of the slot slightly longer into the 'flat' to remove the hairline cracks, this would also help tighten the cylinder into the gas block so long as the above specs were met.
We tightened the gas cyl up to the gas block then backed it off to the next position that the pin would align. But if it was pretty damn close to the next alignment flats anyway. we'd just file a gnats knacker off the face of the cylinder so that they'd align and it'd be tight-ish
hi.
there should be some slight rotation of the gas cylinder.
To reduce any excessive rotation/looseness, metal was filled from the front of the gas cylinder (so it screwed further in to the block). until the other flat was in the position to allow the pin to pass without puckering the tube. there should still be a little movement (in a trade test) but in normal work we always used to do them up tight as they would become loose with use.
(any slight loss of length was compensated for with the carrying handle nut. if necessary the two slots would be lengthened by a very small amount (1/2 the gas cylinder thread pitch)
As a matter of interest Jeff, I'm not sure that there was an actual thread for the gas cylinder except that it was a metric thread over a diameter. As a result, it was difficult to clean out the threads after you'd got a split gas cylinder off the rifle. They were alwaqys c\rboned up due to the gas venting into the thread.
At our big Base workshops (and maybe the bigger Field workshops too) we had the male end of a return spring tube cut down the thread and case hardened and being the same thread on a diameter, it was used as a cutting tap to clean out the fouled up carbon from the gas block.
Someone told me that the return spring tube nut at the bottom could also be used to do the same job. I suppose it could, providing the thread/diameter was identical.
There, another simple Armourers tool for you L1A1 fiends
Ohh bugger another 'locally made' tool to find LOL