The Lyman
GPR has what a lot of folks call a "slow twist rate" of the rifling. As such, it shoots patched round ball well. Now the twist rate in an of itself doesn't necessarily mean it would not shoot a conical bullet well. The Pedersoli 1853 "three band" Enfield rifle is a well known target rifle, and it shoots conicals well with an even slower twist rate than the GPR.
But the combination of the depth of the rifling, usually means that the GPR does not like conical bullets very often.
Lyman also makes the
Trade Rifle, which is 1:48 twist, and it will often shoot a conical bullet well. IF you really want a rifle that will shoot both, that may be the better option, when it comes to versatility.
There is a myth that the 1:48 twist rate in any modern BP barrel is a "compromise twist rate" so the rifle can shoot either round ball or conical bullets well. That's true, a 1:48 twist rate will normally do well with both round ball and conical, but it is believed to have been the most popular twist rate for round ball rifles, because so many surviving antique rifles from the time
before the conical bullet, have that or very close to the twist rate. The "compromise twist" idea was a marketing idea that works (imho), and continues to this day.
Advantage of the conical bullet. It's simpler to load. It was invented as a speed loading round for combat with rifled muskets. LONG after the conical bullet was readily available, hunters stuck with the patched round ball for large game, and especially for large, dangerous game. You are not going to get a fast enough reload to get a second shot at the large game. From my observations the folks that get a follow up shot are using double barreled rifles.
Possible advantage of the conical bullet..., more mass. For really tough hides like a boar, or really large animals such as Elk, Bison, or Moose..., some folks like that. The drawback is that most folks are going to need to up the powder charge 25% to 50% to get the trajectory they have with a patched round ball.
Do you need that extra mass? A .530 round ball is 224 grains of soft lead. That's a pretty heavy bullet in its own right. The lesser mass means faster muzzle velocity compared to a conical using the same powder charge, and a flatter trajectory due to shorter flight time to the target. Well, some say the heavier conical with go deeper into the animal while the round ball deforms a lot. They fail to understand that yes, all other things being equal,
that sometimes is the case, but also the round ball shooter is quite capable of using a
lead alloy round ball, that deforms less and penetrates deep as well. In a very short rifle, such as a TC
White Mountain Carbine, or the Lyman
Deer Stalker with 24" barrels, you may want that extra mass, as boosting that powder charge much above 80 grains may not give you a significant increase in velocity. In your case though, this doesn't apply with the 32" GPR barrel.
Advantage(s) of the round ball. Better trajectory, and less recoil. You're using a rifle with a metal butt plate whether you use a GPR or a Trade Rifle. That recoil IS going to be a factor in your shooting enjoyment, and the question then is, if the deer don't know the difference and are downed just as well with a .530 round ball launched with 70-80 grains of 3Fg, compared to a 300+ grain conical bullet using 80-100 grains of powder, then why are you beating yourself up with all that recoil?
I have taken my fair share of whitetail with a .530 patched round ball and 70 grains of 3Fg. I can shoot all day and not wake up the next morning with a large shoulder bruise, and I can raise my arm over my head and wave goodbye to the other BP shooters at the end of the range day....some of the guys with the heavy conicals and the large powder loads can't say the same.
That's my two-cents. Other's results may vary....
LD
