Originally Posted by
skiprat
At my 1st Unit we had an Air Defense Battery that used to run the Divisional All Arms Air Defense course, 2 weeks of firing at radio controlled aircraft.
Using the L37 version of the GPMG ( fixed gas regulator....So firing as fast as 1000 rpm) 24 guns for the whole Div. .... Inspection of the guns after the shoot I dropped the bore gauge 0.297 and it ran all the way through as it should...
Then I dropped the 0.306 ( to measure throat erosion) it should not enter the barrel more than 4 inches (including the chamber) the .306 ran the full length of the barrel freely.
We sectioned the barrel ( had nothing better to do for the week) there was no visible rifling in any of the bore, it looked more like the surface of the moon.
The throat had opened up wider than the neck of the round, and the erosion was not even along the length of the bore, more like a series of bulges.
The gun was still firing (all be a bit slower!) all the way till the last round down range
At the start of the shoot the barrel was well within spec, as they were inspected every 6 months..