The British Standard thread gauge sits on the muzzle after threading


Lathe-Time We now moved to the adjacent machine shop and the rear end of the barrel was chucked up in the lathe, a mandrel inserted into the muzzle and ‘clocked’ by positioning a dial gauge tip against it, rotating the chuck/barrel manually and watching the indicator needle showing the mandrel’s alignment, initially poor, with the lathe axis and hence the cutting tools. A series of adjustments saw the needle movement diminish rapidly and in what seemed a remarkably short time but was actually several minutes, the mandrel didn’t generate the slightest tremor on the gauge reading.


“Setting-up barrels took me forever when I started gunsmithing,” says Dave, “but you learn tricks and get a feel for the job as you go along.” The mandrel and gauge were removed and the lathe started up. “Look at the mouth of the bore” says Dave, and sure enough I can’t see a trace of wobble in the little black hole as it rotates at several hundred rpm. I’m assured the eye is a remarkably fine judge of runout. Then I’m instructed to refocus and look at the whole


crown area, and to my amazement it and the outside edges of the front of the barrel are clearly wobbling all over the place. The bore is not dead centre in the barrel, the outside circumference of the hammer-forged tube’s muzzle area isn’t round and the factory crown was anything but true.


We can’t re-profile the barrel exterior, but we can sort the crown out and that’s what was now on the agenda taking up more than half the time put into the ‘tune-up’ exercise. First, the muzzle was skimmed, refacing it at 90-degrees to the bore. If we’d been doing a straightforward re- crowning job, various countersunk cutting tools would have been brought into play now but Dave had offered to thread the muzzle for a sound moderator and this was done first. As he says, most of the time spent here is to set the barrel up in the lathe and another quarter hour of machining time spent on threading only adds marginally to the cost. So a reduced diameter section was first turned into the final half-inch or so of the barrel and the lathe reconfigured to cut the threads onto it.


Target Shooter 25


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