The local gun shop bought about 20 of the Blue Sky M1icon Rifles when they were imported. To a rifle they were all virtually worn out. The bullet test revealed that some would take the bullet and part of the case, while a few would only go up to the cartridge case. It was a daily operation to put the op-rods back in their track, as most would jump out when pulled back by customers.
The M1 Carbine barrels must have been much softer, as was previously posted, some of the barrels were "egged" by the stamping process.