Originally Posted by
Rick
Thanks for the response Bruce. I have some general knowledge of the evolution in military bullets from about the time of the Minie ball design, but not as specific as you recounted.
My last comment was towards the suggestion that barrels may have been lapped in an attempt to regain some velocity lost due to barrel lengths decreasing rather than for some other reason i.e. a finding that it would reduce barrel fouling. I would assume that trials before production began would have supported that additional expense and time to do that, for whatever reason.
As to the possibility that lapping a barrel results in significantly increasing muzzle velocity, my experiences with 5.56 and 7.62 barrels being cut down looking for a uniform accuracy node (and my reading over the years) suggests that in a caliber with the expansion ratio of .303 British, you would see a velocity loss of somewhere around 20 - 23 fps for each 1" reduction in barrel length. I am certain that at some point in the past, multiple curious people have tested that with Lee Enfield barrels by cutting them down while chronographing the results.
Black powder would probably show some different results regarding how much velocity was lost per inch of barrel; probably a greater velocity loss per inch of barrel. But in either case, I can't see any significant recovery of velocity by way of lapping barrels after the drilling, reaming, and rifling is complete. I suppose it could be possible, but I spent a day carefully lapping my Long Branch rifle chosen for competition use in hopes of wringing every bit of grouping ability I could out of it, as well as preparing it for use with cast bullets in CBA military benchrest matches. I didn't see any significant improvement as far as chronograph results.
It is a fine barrel for cast bullet shooting in that I don't get any leading in the barrel unless I do something wrong, but it is quite possible that has little to do with the effort I spent casting lead laps to lap the barrel from end to end to be as uniform as possible. At the same time I also had custom bullet moulds cut to fit the ball seate/leade as tightly as possible to maximize obduration of the bore as quickly as possible. That was accompanied by lead alloy selection and heat treating the bullets after casting to best match the pressures of the loads being used. Other than if I had started out with a fugly bore on the rifle, a custom mould and some applied casting science probably had more to do with the results than all that time I spent lapping the bore.
I remain curious as to how manufacturers, especially Long Branch, made the barrels. If they started out with blanks of near finished length and then drilled, reamed, and rifled and when and how they did all the profiling and threading to end up with a barrel that could be screwed on to the actions properly indexed during times of wartime manufacturing. I'm not a collector or historian, but I wonder how many rifles every single day left armories like Long Branch in WWII or BSA or somebody else in WWI. Dozens per hour, certainly. If they lapped them prior to applying the finish and attaching them to the receiver, that would be an additional cost in labor, time, and expense. Minimizing those costs is reflected in the simple sight the Savage manufactured No. 4s left the factory with.
