Projectile Length vs Twist Rate

[rodwha]

I'm considering either a Lyman Great Plains Hunter with the 1:32" twist and the Deerstalker with the 1:48" twist with shallow grooves.

My current Deerstalker with deeper PRB grooves did quite well with the 320 grn Lee REAL when I used a wad so I'm certain that length will work well enough it seems.

But I'm wanting a rifle set up to shoot longer range that I'd top with a Malcolm style scope for shooting beyond 100 yds and out to 200 yds if I can find a load that will work (all I've found is a .40 cal Hornady SST so far). If 175 yds is about it then I'm fine with it.

My questions are A) what is the shortest projectile a 1:32" twist would stabilize out that far, and B) what is the longest a 1:48" twist would at muzzleloader velocities?

I may well end up going to Accurate Molds for my projectile but haven't decided against a commercial one. Hornady seems to be one of the better ones having aerodynamic bullets in larger calibers, but there's the issue of velocity such as their .444 Marlin 265 grn SST. Doubt it would be a good bullet for my purpose. Same with the 250 grn SST for the .450 Bushmaster.

As an aside how well does a somewhat pointy large (.429-.452") bullet work when the meplat is rather small? I don't want a bullet that will leave a pencil wound.

[triggerhappy243]

You should read all the posts idahoron has put up. His testing would make short work for your testing.

[daschnoz]

Lookup Greenhill Formula.
http://kwk.us/twist.html

If you have the twist rate and need to solve for one of the input values, it's straight forward algebra...

[rodwha]

I've talked with IdahoRon before and know about his successful use of the Lee .50 cal pistol bullet, as well as the Lee 320 grn REAL not working well in his 1:32" twist.

There is a lot of drop with that combo. I was hoping to work within a 4-5" point blank out to 200 yds. I can get 175 yds with the REAL on paper with an estimated velocity.

I've also looked at various Hornady bullets using sabots. I'd prefer a cast bullet but would use a sabot if it greatly improved my range.

And so I'm considering if a drop-in Lyman Deerstalker barrel with the 48" twist is ideal or if I should just get a GPH with the 32" twist. But it seems the faster twist might demand a much bigger bullet reducing the range.

I thought the Greenhill formula wasn't quite right with muzzleloader projectiles? Using it to see at what velocity it would shoot a PRB showed about 750 fps, which is hooey. Does it use a lower figure than 150?

[Good Cheer]

rodwha,
Just my thoughts, mi twain centavos...
What muzzleloading projectile and barrel will give you the longest useful hunting distance, or perhaps in your case the distance you have figured out that you need to achieve, might be something to closely calculate rather than buying someone else's product.

[johnson1942]

give me the cal and the bullet length you want and i will give you the twist you need. done this dozens of times.

[rodwha]

.50 cal is readily available, but I emailed Investarms and found I could order their .45 cal barrel from Germany if I went that route, but it may well be cheaper to have a barrel lined to .45 cal. And were I to have a barrel lined I could just as well go to .375 or .400 or some such.

I don't have a specific bullet in mind, but know that I don't want to have to use a very long bullet as it would give a rainbow trajectory, and I'm wanting an easier point blank way as it greatly reduces mistakes as I see it.

[koger]

Any of the heavier, accurate projectiles will have a rainbow arch, just the facts. I have a Hot Rod renegade .50 and shooting heavier projectiles has a good arch at 200-300yds, same with my 1-20 twist .45 caliber side hammer I built, 430 grains up to 500 or more if I want. I have played with scopes on them, with mildots, and figured which one to use, and at what scope power setting, and leave it at that. I am shooting 2" groups at 200yds with saboted 260 and 300 grain PT tips with Harvester crush rib sabots. 100yd groups are a ragged hole.

[johnson1942]

some guys arch them into good groups at 800 to 1000 yards. not hard to learn.

[Good Cheer]

If only they hadn't mailed my .695 sizer to the old address I'd be arcing a few of those.

[Boz330]

At BP velocities range estimation is going to be paramount. I doubt that you can get enough velocity to get a 4-5 inch point blank range to 200yd with any ML short of a smokeless.

Bob

[Good Cheer]

What a great excuse to put a laser range finder on my as yet only visualized steampunk front stuffer.
Ah, come on, stop laughing. It might be a fun project.

[rodwha]

If it's a place I'll be hunting regularly I'd calculate my outmost range. But a rangefinder would be quite handy, and with one stretching that distance and working with the crazy trajectory wouldn't be that hard to do once shooting at longer ranges was worked out well.

But I prefer to keep things more simple. At closer ranges aim a few inches low and out at distance aim a few inches high. That is assuming my load is accurate enough to give me small enough groups to be confident that my bullet will strike within a small enough circle.

[daschnoz]

What a great excuse to put a laser range finder on my as yet only visualized steampunk front stuffer.
Ah, come on, stop laughing. It might be a fun project.

Go for it. I'm not laughing. Hey, I put together a muzzle loading upper for an AR-15. I'm sure you'll get the same "*** is that" looks at the range that I get.

:bigsmyl2:

[Standing Bear]

Years ago a couple of shooting buddies got tired of big mulies staying 300 yds out. They bought surplus .45-70 barrels from Numrich and built side lock MLs w Creedmoor style tang mounted sights. This worked well.

A barrel lined to similar dimensions would work as well. As said earlier a good range finder is essential.

[Good Cheer]

My TC New Englander went down a similar path.
The barrel got relined to have a .458 bore to shoot as dropped from the mold 45-70 boolits.
Now it's a .45-(fill in the blank) shooting caseless rounds.
:-P

Also works pretty good with Keith SWC's patched up to bore. Would like to try paper patching some 454190's some day. Too many things to do and oh so little time!