Round Ball? Minnie? Bullet? Twist rate? Help.

S

Superhouse 15

New member
Ok, I got my second black powder firearm, this one a .50cal inline percussion. At first it wasn't reliable firing the cap, but a little file work on the nipple fixed that. In the junk collected in the powder cabinet at the gunshop I found Minnie bullets and balls that fit, as well as some solid bullets that resemble the Remington "Buckhammer" slugs, but with wide grease grooves. The local D ick's sporting goods has sabot bullets in various weights. During test firing I loaded FFFG powder at 40gr behind a Minnie lubed with "Bore Butter" and it stabilized at about 20 yards and hit a paper plate. For convenience I made some paper cartridges (that worked... until I bit the end off like the guy on Youtube did, only I got some tasty black powder in my mouth). Development of those will continue.

Anyway, now that it's reliable, does anybody know what style of projectile is correct with a given twist rate? Is there a chart somewhere or a rule of thumb? Anybody have any advice on powder weight? I do know two things, one: Minnie bullets need a certain minimum powder charge to expand and grip the rifling, and two: I don't want to blow my face up. Is there a projectile that works well in any barrel? It has an old but well kept Weaver scope on it, 4X, and I want to be able to shoot it at at least 100yds to take advantage of that. For hunting it's probably realistically going to be shot at 30 to 40yds max.

And while I'm overloading everyone with questions, What about the pre-formed powder pellets? Some even come in a kit with sabot bullets and pellets of powder. Does anybody know how those taste?

Thank you kind black powder Gurus.
 
The formula you want for twist is Greenhills formula I can give you it in a later post if you want it. For the moment so as not to confuse you. Lyman BP hand book say a 22" 1 in 24" twist barreled 50 cal Buffalo HP conical of 350grs @1148ft/sec with 60grs of 2f Geox behind it. The twist on barrels designed for balls is 1 in 48. The largest bullet on the chart is 490gr anything less than that should stabalise lovely in a 1 in 24" barrel. 120gr Geox gives 1551 ft/sec. Tell me your powder bullet/ball weight and barrel length and I'll print more info.
A round ball requires less twist to stabalise than a conical bullet If your barrel is 1in 48 twist it will stabalise round balls a conical bullet is required to make the bullet heavier if you made one 200grs(not very conical) it would be much less stable than the round ball. It would almost certainly not stabalise. There is no chance a 350gr conical will stabalise in a 1 in 48" twist barrel
I love maths and formulas but hesitate to print them as not everyone feels as I do. However if you want the info I'll help as much as I can.
mik
 
Last edited:
A round ball requires less twist to stabalise than a conical bullet If your barrel is 1in 24 twist it will stabalise round balls a conical bullet is required to make the bullet heavier if you made one 200grs(not very conical) it would be much less stable than the round ball. It would almost certainly not stabalise. There is no chance a 350gr conical will stabalise in a 1 in 24" twist barrel
Click to expand...

If that statement made any sense it would be easier to reply to.
As a TRADITIONAL muzzle loader with 40 years experience, I (and many others) can tell you the slower twists (e.g. 1:48 to 1:72, or even slower) are better suited for round balls. Elongated bullets stabilize with faster twists (faster than 1:48). Contact the maker of your inline or look on the internet for information.
Start with moderate loads and work up to find what works best. Shooting is the only way to dial in your rifle.
BTW, if you are truly worried your rifle might blow up, hang on wall and do not shoot.
 
Please read my post again I have edited out my mistakes. My knowledge of ballistics is far superior to my command of the English language.:)
 
Most period round ball guns I've examined have twist rates of 1 in 50 or slower. One I saw years ago had a twist of 1 in 90.

Thompson Center for years adopted a compromise twist rate in its guns of about 1 in 48. They would adequately stabilize both round balls and conicals.

When Pennsylvania mandated round ball only, they came out with the Pennsylvania Hunter, which was a .50 with a twist rate of 1 in 66.

The general rule of thumb is the shorter the bullet, the slower the twist rate needed to stabilize it.

The longer the bullet (and heavier, generally) the faster the twist rate.
 
What Mike said. A 1:48 is a good medium ground for round balls and conicals but not ideal for either.
 
The rifle twists I mentioned are from Lyman BP reloading manual. If you buy a rifle how can you check its twist rate. I would have to take it to a gun smith.
 
Going by Beagles link. With a slow twist you're not going to have enough barrel length to make a full turn. I like to push mine all the way down to start with but it doesn't matter. Just mark it at the muzzle in line with the front sight. Push it in or pull it out whichever way you prefer until you get a half turn. Mark it again. Measure between the marks and multiply X2. Or you can go a 1/4 turn and multiply X4

I can't believe I said divide originally. Multiply X2 not divide as I originally stated.
 
Last edited:
Keep in mind that Greenhill's Twist Rate Formula isn't applicable to round projectiles, and it's really not ideal for any projectile that isn't at least 2.5 or 3 times longer than it is wide. You're better off just going with general guidelines and TLAR (That Looks About Right) than you are trying to justify a particular twist rate by mis-using Greenhill's formula.
 
Wow, thanks a lot. I am a gunsmith and as soon as I get to the shop I'll measure the twist rate. I loaded 40gr of FFFG in a brass measure behind the round ball and the Minnie. I also tried a load of birdshot strictly for testing purposes with 45gr but it was dramatically unsuccessful, not surprising considering the rifled barrel and small charge of shot. Bring on the math, please. My first black powder gun was a Spanish Deringer that I was finally able to safely fire with a patched ball and 25gr of the same powder. Still not exactly sure of an appropriate charge weight but I was cautious.
 
Forty grains is a mighty light load in a .50 rifle. Accuracy suffers if a load is too light, not just for Minie balls but also with patched roundballs.
Most people put around 70 to 90 grains in a .50 when shooting patched round balls, even heavier sometimes with the slow twist barrels.
 
40 grains???? Did the ball even make it to the target LOL :D. I'm just playing, but yea you need to put some FIRE to that rifle. 90 grains seems like a sweet spot in my .54.
 
I was certainly taking a cautious approach to the first few shots. And I did mis type. The powder is FFFFG (four F's). I'll give it a boost and try starting at 70 and working up from there. I'm stuck at work today, going to measure and test fire tomorrow. I believe I'll wait on the Sabot bullets until I see what I can get with the Minnié accuracy wise.
 
I don't have no where near the experience as some of these guys here. But FFFFg is generally a pan powder for priming flintlocks. Fg is cannon powder, FFg a rifle powder, and FFFg a pistol powder.
 
Safety!

I'd stick with the light charges until I knew what gun I had. Some of the legacy inlines are unsafe with major loads. A muzzle loader can be accurate loaded to different levels. If you are shooting for smiles load it light. I would not trust heavy loads without at least remote firing with a proof load. It's only prudent. Try googlin Randy Wakeman- CVA. A cautionary tale- at least something to think about.
 
You must log in or register to reply here.
Back
Top