Longest projectile for .58-caliber?

[Naphtali]

What is the longest .58-caliber projectile that remains stable with full power FFg loads from a 1:48 twist barrel?

OR

What is the conical ball (or minié or R.E.A.L) mold that drops the heaviest .58-caliber projectile that remains stable with full power FFg loads from a 1:48 twist barrel?
***
I specifically rule out saboted bullets, bullets not made of lead, bullets for which there is no available bullet molds to buy.

 

[poordevil]

The Lyman mold for the Parker_Hale at 566gr +- might be the heavest

P

 

[nkbj]

Speaking in broad terms, a 1 in 58" twist is good for a (1.5 x .58") bullet length. So, 1 in 48" is good for a longer length of bullet. Add to that really honking it and there probably isn't an off the shelf "muzzleloading" mold configuration that won't stabilize in a 1 in 48" twist.
NEI (El Paso) has a longish multi-groove listed at .577 diameter that appears to be available in various lengths. It's #393. It might work with three lube grooves in a 48" twist.
Wish my .577 x 48 twist would get here.
Going hog huntin'?

 

[Billnpatti]

The best length of bullet can be calculatged using the Greenhill Equation. You can find it by Googling "Greenhill Equation" or by picking up a book at your local library entitled "Understanding Firearm Ballistics" by Robert A. Rinker.

The optimum length bullet is a function of caliber, twist rate and velocity. There are other factors that effect the optimum bullet length such as temperature, air density, etc. but these have a much smaller effect than the first three. It would be handy to know this equation for future bullet selections.

 

[bufallo]

Davide Pedersoli bullets moulds,
code USA 309-577, diameter .577, bullet weight 620 gr... super for my Kodiak .58... http://www.davidepedersoli.com/?item=AccessoriDettaglio&CategoriaId=1335&lang=en

 

[Naphtali]

Bill:

I just bought a Kodiak Safari and used Greenhill's Formula to calculate bullet length stability for .72-caliber with 1:72 twist. Recently, I began a thread about Greenhill's Formula with the Safari. The thread showed much inconsistency regarding efficacy of the 150 constant. In PMs and email correspondence more of the same.

That's the reason for this query. Too many responders informed me of contrary conclusions. So the follow-up method is inductive reasoning - that is, to identify what people who cast and use conical lead projectiles have found works blandly and uneventfully.

 

[Naphtali]

The bullet is stable? What load data have you? Please identify exterior ballistics. This is exciting.

 

[paulvallandigham]

The Greenhill Formula need to be adjusted for the velocity of the projectile you are using. The standard formula is set for guns firing bullets at less than 1500 fps.MV.

The formula to use to determine most efficient bullet length is:

L= 150(180) x D X D divided by T, where L is the length of the bullet, 150 is the number to use for bullet up to 1500 fps MV, and 180 is better for bullets that may be fired at faster speeds. We are talking lead bullets, here, NOT jacketed bullets, so there is very little reason to fire a Lead BULLET in a BP rifle at more than 1800 fps. The lead, even hardened, begins to strip off, when you drive it much above 1800 fps. leading your barrel a lot.

D= Diameter of the bullet, and you multiply it by itself to Square it. T= Rate of Twist in the barrel you choose to shoot the bullet in.

To find the optimum Rate of Twist for a given length of bullet, square the diameter( caliber), times 150(180), divided by the length of the bullet. The Greenhill formula chart I have was published in RIFLE magazine, which tends to address projectiles for modern rifles. As such it stops at .458 caliber bullets, and does not give the formula for large diameter bullets. The Table I have is a reprint of the same table published In Handloader Magazine, No. 120( March-April, 1986) in an article written by Kenneth S. Hulme, titled, "Basics of Twist." The table was developed for flat based, round nose bullets.

If you are shooting a bullet with a different shape, adjustment may be needed in the formula. Since most bullets fired in BP rifles are flat based, and round nosed, I believe the information from the table is useful for our purposes, here.

The reason you get different information from different people is that the Greenhill formula has these basic assumptions underlying it, which you have to know to get good results. And, the formula is often stated different ways, based on what information you are seeking.

The " Caliber times Caliber time 150, divided by the length of the bullet in inches= ROT, is the standard Greenhill formula.

To answer your question, seeking the longest bullet you can shoot in a given ROT barrel, you need to use the first version of the formula I describe above.

I hope this helps you, and others clear up any confusion you might have about the formula. Understand that No formula can possibly control for all changes. When you shoot a heavier bullet, for instance, in a barrel with a ROT not designed to stabilize that bullet, you probably won't notice much difference until you are shooting at targets at 500 yds, and further. Then you will see the bullet yawing, or even tumbling when it goes through a paper target at long range.

If you are not shooting targets at 500 to 1,000 yards, I can't see much reason for you to be very concerned about " maximum bullet weight " for a given ROT barrel. The recoil these heavy bullets cause should be of more concern. Have you done any kind of comparative penetration testing with any bullet??? Have you seen the damage that any 12 gauge(.73 caliber)1-ounce, foster-style slug will do to a deer, much less how far it penetrates? Can you handle the recoil from a shotgun firing these slugs? Can you hit a target with great accuracy at just 50 yards with a shotgun slug??? And do it repeatedly??

I meet and have met a lot of shooters over the years who just can't be happy until they own the baddest recoiling, largest caliber gun on the block, or whatever. :nono: :shocked2:

Then they go out and shoot it. :shocked2: :hmm: Usually after one session, they are looking for a buyer. :surrender: :thumbsup:

 

[nkbj]

Bill:

I just bought a Kodiak Safari and used Greenhill's Formula to calculate bullet length stability for .72-caliber with 1:72 twist. Recently, I began a thread about Greenhill's Formula with the Safari. The thread showed much inconsistency regarding efficacy of the 150 constant. In PMs and email correspondence more of the same.

That's the reason for this query. Too many responders informed me of contrary conclusions. So the follow-up method is inductive reasoning - that is, to identify what people who cast and use conical lead projectiles have found works blandly and uneventfully.

Yep, the more responders you get the more contrary and contradictory the responses will be. But to look on the bright side, while they can't all be right, where else could such a concentrated dose of distilled experiences be had?
My philosophy concerning twist is derived from the only wisdom gained from Mardi Gras...if you don't have excess you don't have enough.
My best solution is an adjustable length mold with a small hollow base because I can't adjust the twist and don't need to buy multiple molds.

 

[bufallo]

this bullet, any problem... balistic data? I havent chrono... my loads 120 gr FFFg Vezuvit LC, Czech made, or Swiss No.3 , 100 gr..
it is very hard load for me, my weight 70 kg...
target loads 80 gr Vezuvit + .58 REAL...
email from [email protected] ( Gloria)
Dear Mr. xxxxx,
Thank you for your inquiry and for the preference in our guns.
The USA 309-577 is a bullet mould making minié bullets 14.65 mm diameter, ideal to shoot in our 1861 Springfield rifle .58 caliber.
The USA 309-580 makes bullets 14,73 mm of diameter and the usa 309-585, bullet having 14,86mm in diameter.
Here some more information about the loads that gave us the best results:
Our general manual reports the target loads that gave us the best results. Being target loads they do not need to be larger loads, in fact with 75 grs. of Swiss Black powder # 2, round ball .575" with patch .010" we had a good grouping.

We have various loads that gave all good results:
75 grs. of black powder (Swiss no.2) round ball .575" (our USA 520-575) patch .010" (our U.1054)
85 grs. of Swiss no.2, round ball .570" patch .010"
85 grs. of Swiss no.2, minié bullet 505 grs.
90 grs. of Swiss no.2, minié bullet 620 grs. (our USA 523-577) (our bullet block USA 309-577)
90 grs. of Swiss no.2, minié bullet 640 grs. (our USA 523-580, sized to .578) ( our bullet block USA 309-580) (our Sizer USA 515-580)

Our USA importer got good hunting results with:
100 grs. of FFg round ball .570" patch .010"
90 grs. of FFg conical bullet either 525 grs or 560 grs.

Best regards,

Customer Service

more very interesting informations about Kodiaks is whitesmoke.co.za , Discussion forum

 

[BrownBear]

I don't know if they make it in 58 cal anymore, but the Hornady Great Plains is a heck of a conical in my rifles. Can't recall the weight right now. Sorry to say, Lyman doesn't make the equivalent mold in 58 cal like they do in 50 and 54 cal. I've hears stories that LEE has the pattern for a custom mold that's the equivalent, but I haven't investigated that yet.