I grew up hunting with shotguns and .22 cal. rifles, but had no experience with high power rifles until I joined the Marine Corps. I was amazed at the thought of shooting a peep sighted rifle at 200 yards offhand before I started doing it. In Boot Camp, I ran 7 consecutive Bullseye’s at the 200 Offhand until I fired my 8th shot, and in recoil, realized I had lined up on the target next to mine. It was also a bullseye, but did not count as it was not on my target. After that, things went downhill fast….Grin.
During Boot Camp leave, I bought a .50 cal. TC “Hawken” rifle. Using balls cast from the mold provided and their patching material and with the 60 grain load they recommended, I sat down on frozen Iowa ground in January, took up a good sitting position and placed three balls where the maximum spread between two shots was 1 ¾” on a target by actual measurement. I knew I did not yet have the best/most accurate load for the rifle, but I was hooked.
Within less than two years from that date, I began my one year apprenticeship to build National Match Rifles and Pistols, Sniper Rifles, etc. for the Marine Corps and spent most of the next 23 years in that capacity. While the Junior Armorer on THE Marine Corps Rifle Team in 1975, I learned the importance of “touching up the crown” or refreshing it, every 400 to 600 rounds to keep the rifles shooting at top notch accuracy.
During those early years, I also went to Friendship to compete with flintlock rifles and smoothbores and see some of the better shooters on the Primitive Range and from the “Tin Tipi’s,” though much more on the Primitive Range over the next 7 years. I also began working original and reproduction Civil War guns at the Spring and Fall National Shoots of the NSSA for 23 of the next 30 years.
You really can’t compare having to refresh the crowns of modern rifles to muzzle loaders all that much. Modern rifles “burn out” the muzzle crowns much faster than in muzzle loaders; from the gas igniting at the muzzle, the higher pressures and the fact we shoot a LOT more rounds per year than muzzleloaders are shot. Also, in Muzzleloading, we are not trying to keep 10 shots within a 3” circle fired from a machine rest at 300 yards on a NM M14, or a 4 3/4” ten shot group fired at 1,000 yards from a bolt action sniper rifle in a machine rest. This last group size was fired from a Model 40A1 sniper rifle with the then “new” long range ammunition in the mid 1990’s. I was the Shop Chief of the Marine Corps Rifle and Pistol Team Equipment Repair Shop when that group was fired and was there in person to witness the shooting and measuring the group size. Yes, we were astounded at that accuracy.
The famous “11 degree crown” on highpower NM rifles actually came from a test made by Springfield Arsenal on an EARLY M1903 cartridge/bullet combination. It was found it was best for that bullet, but not all bullets of that time. Still, once found, it became the indisputable muzzle crown angle from then on and was used on GI crowning tools throughout the era of the Springfield 03 and M1 Garand. Benchrest shooters later actually proved the angle of the crown was not nearly so important as how exactly uniform the crown was cut/formed – no matter the angle.
If a muzzleloading barrel crown is cutting a patch, that often means there is a burr or sharp edge in the crown. That is not good for accuracy even on modern rifles and is strictly avoided when touching up modern rifle crowns. However on modern rifles, it won’t take long for the tight fitting bullets to break off a burr. That would not happen for many more rounds fired from a muzzle loader.
I think the reason one can get away with using the thumb and garnet paper to smooth a muzzleloading crown is the bullet does not directly engage the lands and grooves with a patched ball. I also think that most of the time, you don’t reach the crown right at the ends of the lands and grooves (in the barrel) when you do that and that’s where a uniform crown is the most important for accuracy. Looking at the last picture that Daryl submitted, it is easy to see the crown right at the ends of the lands and groves were not polished by the garnet paper. (On NM rifles, we made sure we cut deep enough with the crowning tool that the end of every land was recut.) Still, I’m pretty sure if a person did it enough to seriously deform a uniform shaped muzzle crown, it would negatively affect accuracy.
It seems a good number of people have reported a loss of accuracy in a patched ball barrel when the muzzles were coned. Perhaps this was because the cones were not cut concentric to the bore? Or perhaps that allowed the bullet sprue to shift positions in loading from shot to shot. I’m not sure about that, as I don’t have much experience with coned bores.
Over the years, I have used different bore guides to recut the crowns on more minie ball barrels than patched ball barrels (both repro and original barrels of both types), though I’ve cut a couple dozen of the latter with 11degree, 12 flute carbide cutters we used for modern rifles. It always made a positive difference in accuracy, though the more worn or non uniform the crown was, the more noticeable the difference in accuracy after crown was recut. ALSO, if the muzzle face was not uniform to the bore, that leads to more inaccuracy even when the muzzle or bore crown was done in a uniform manner. It’s often easy to see if the muzzle face is not concentric to the bore when you cut the barrel crown with a pecision cutter, because the barrel crown then is not the same distance all the way around the barrel.
Gus
