My latest 50 cal muzzleloader has a 1:48 twist barrel …, use for hunting deer that offer reasonable accuracy and expansion...,There are so many bullets on the market now it's hard to wade though all the options.
OK well first...if it's a modern, conical bullet (or also all lead) with plastic engaging the rifling, I seriously doubt you will find one that's "reasonable" when it comes to accuracy with our old style rifling depth (regardless of the twist rate). That eliminates more than ½ of what's out there on the market.
So you are left with:
Patched Round Ball
PA Conical
Flat Base Conicals
Minnie Balls
Patched round ball as suggested above by many many experienced shooters of both targets and deer (and even larger critters) works great, they have much more experience with these than I, AND I concur with them based on my experience too.
Interestingly, the PRB is not simply just that. There is all lead, giving you the most mass of the round ball variations, and deforming quite well upon impact in most circumstances. Then there are harder alloys, which although they don't deform as easily, they can in some cases give you better penetration. And let's face it a .490 hole,
especially when the wound goes through the animal, is pretty darn devastating. Part of the equation that we can't answer is...what powder level you are using and how accurate is that from your rifle, and..., how well you place your shot. (which pertains to all the bullets, btw)
PA Conical is a hybrid. It's a round ball with a skirt, and you may be in luck as it's available in .50 caliber.
https://www.hornady.com/muzzleloading/browse/50-cal-240-gr-pa-conical#!/
So you get a bit more mass as they are about 70 grains heavier than the .490 round ball, and the idea is that with a 1:66 twist barrel you get simplicity of loading as there is no patch. So they should work in a 1:48 barrel too. (The Minnie ball, a skirted bullet, was invented to speed up combat loading of rifles to thus allow all the infantry privates to be riflemen..., not as a hunting bullet.
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Flat based conicals are just that, conical bullets without a skirt. The Thompson Center versions come in two types, the Maxi-Ball and the Maxi-Hunter. Either one may work well enough for you as TC rifles are often found as 1:48. Hornady makes a conical bullet too. LEE makes the R.E.A.L. conical bullet which you have to slightly force onto the rifling as you load, because the last band on the bullet, the nearest to the tip, is intentionally oversize, so when you force it into the barrel it already engages the rifling. Flat based conicals have more mass, so will probably kick you more during recoil. They may, especially if you increase the powder load a bit, give you better penetration on really large game. But if you're already sending the round ball through the animal, that same animal isn't going to notice a difference when you use a conical (imho). They don't "bust brush" as some people think, and even when not using a patch the reloading isn't fast enough to give you a quick, second shot. For deer and smaller, I'm not sure they are ever an advantage.
Minnie Balls are the first well known conicals. They have a "skirt" on the base, which is intended to flex outward when fired due to the expanding gas, the skirt going into the rifling, to cause the bullet to spin. There are a couple different bullet shape variations, and these tend to be the heaviest projectiles that you will find. As mentioned they are meant to give a combat infantryman a quick reload, but they do hit very hard...IF you need that. I would prefer these if I was going to defend myself vs. a grizzly...actually I'd prefer a modern cartridge in .500 for that, but that's for a different website altogether.
LD
