Can you shoot conicals in a Kentucky rifle?

Claven2

Claven2

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Anyone know if you can shoot a heavier conical .45 in a .45 round ball kentucky rifle? Or is this s decidedly bad idea?

If you can do it, I assume you would have to reduce the charge for the somewhat heavier bullet, no?
 
The real issue is the twist rate of the barrel. Use the greenhill formula to figure it out. maximum length is 150 diameter squared over twist. Normally you would use a twist rate 1" faster than the formula.

cheers mooncoon
 
There are short conicals intended for use in round ball rifled barrels. I've not shot them, but the Lee REAL bullets come to mind, as do Minie style bullets. Both of these avoid the problems of loading the bullet straight into the rifling, which was a problem with patched picket bullets in the 19th century.
 
Hmm... so
1:36" bbl = 1:920mm
35" barrel = 890mm
.45cal = 11.2mm
If L=(150XD^2)/twist

Then (150X11.2mm^2)/920mm=20.45mm and that makes no sense???

Can someone please explain what part of this formula isn;t being applied right???
 
And another thing - in a Kentucky rifle (mine is the Armi Sport .45), do I need to reduce the charge? And if so, by how much approx?
 
OK, found this on the hodgdon site:

45 CALIBER POWDER MEASURE SETTING TRIPLE SEVEN FFG
Bullet & Sabot
70 GR. 80 GR. 90 GR. 100 GR.
150 Gr. Knight/Red Hot 1963 2134 2187 2284
180 Gr. T/C XTP 1916 1993 2054 2108
240 Gr. Knight Lead PT 1725 1792 1849 1991
225 Gr. CVA Power Belt 1684 1720 1784 1905


45 CALIBER POWDER MEASURE SETTING TRIPLE SEVEN FFG
Bullet & Sabot
40 GR. 50 GR. 60 GR. 70 GR.
440 Hdy. RB/.020 Ox-Yoke patch 1534 1692 1926 -

so according to this data, you have to greatly INCREASE the charge for conicals. ???

So next question is: Can the barrel withstand that additional pressure safely?
 
Those loads are for sabotted sub-caliber bullets fired from modern in-line rifles. Apples and oranges, in comparison with the patched round ball loads listed below. A conical bullet is heavier than a round ball. This will increase pressure. I suggest that you should start at the lower end of the round ball loads, and increase carefully. I have no experience with Triple Seven, only black and Pyrodex.
 
According to the numbers you provided..........

45 Cal = .451 inch (roughly)
Rate of Twist 1:36"

.451 x .451 = .203401
x 150
= 30.51015
/rate of Twist 36
= .8475 inch
or 21.5 mm

PS: I shoot a .50 Kentucky 1:66 twist using PR bullets 300 gr UL-1 solid conicals. I won't tear one ragged hole, but I am hitting milk cartons @ 100 yrds. Huntsman will atest to that.
 
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Oops, shoulda clarified........sorry

21.5mm is the max length of the projectile that your 1:36 twist rate will stabilize. The greenhill formula just gives you a starting point.
 
When I use Minnie ball or Maxi ball in my .50 cal I up the charge from 65gr FFFg that I use for round ball to 100gr FFFg. Keeps my POI up around where it is for round ball. Still gives me 4" group @ 100 yd off the bench. Your mileage may vary.
 
100 gr FFF with a conical is going to generate a LOT more pressure than 65gr with a patched round ball. It is going to be generating at least as much pressure as a powerful BP cartridge. What rifle are you using?
Something else to consider when hot loading a muzzleloader - what steel is the barrel made from? I suspect that the better inlines are using the same sort of CrMo, like 4140/50, used in centrefire rifles. Other muzzleloaders use CMn steel, 1137 or equivalent. Not as strong, but quite acceptable. There are also ML barrels made from leaded screw machine steel, like Laled or 12L15. In theory its ultimate tensile strength is adequate. It machines beautifully, and a fine bore finish can be readily obtained. It is also brittle steel, particularly when chilled, and subject to fracture upon failure, rather than splitting or bulging. .22 rifle barrels are often made from this grade of steel.
Another consideration is the breeching system. Is the breechplug, patent style or plain made from a mild steel casting, or from a higher tensile steel? A percussion drum system is inherently weaker than a bolster type breech. How well is the plug fitted?
 
I'm using a Pedersoli Tryon with 1" across the flats.
I have a blackpowder book from the 1970's that gives max loads of around 200-250 grains for muzzleloaders. I wouldn't!!
The Parker Hale repro Enfields from the 1970's have a load of 96 grains of powder for a 560 grain Minnie ball they are 58 cal. so I don't hesitate to use the load I do. Musket barrels are thiner than what I use on my Tryon.
 
Claven2 said:
100gr of FFFg is a pretty stiff load, even fo .50 cal. Most books recommend using 100gr of FFg or less, FFFg is a bit hotter.
Click to expand...

That charge is at the top of the pressure load for a Pedersoli (and most Italians). The Italian Proofing House proofs their guns at twice their rated load ie, for Pedersoli, which typically rates its .50 cals at 60gr load means its proofed at 120 gr (from what I gather, they proof EVERY gun barrel, not just a sample). For most Italian guns, you're looking at keeping the pressure more or less under 10K psi in the combo of bullet and charge.

Lyman rates pressure for 370gr Maxi, 50 cal, 28" barrel, 1:48 twist at 9,800 psi with 100gr GOEX. 110gr = 11,000psi, which is too high.

The same load with Pyrodex select drops out at about 75gr.= ~10,000 psi.

These barrels are little longer, so the pressure goes up.

Lyman doesn't rate FFFg with Maxi, but with round ball and GOEX you get this:

FFg: .490 ball 28" 1:48 120gr = 7,800 psi

FFFg .490 ball 28" 1:48 90gr = 9,900 psi (7,500 psi = 60gr with FFFg)


For claven - .45 cal:

round ball .440 Goex FFg 28" 1:48 60gr = 9,800 psi 70gr = 11,000 psi
round ball .440 Goex FFFg 28" 1:48 50gr = 9,800 psi 60gr = 11,300 psi

Maxi 245gr Goex FFg same barrel & twist 40gr=9,500 psi 50gr =11,100, and FFFg is off the scale at all loads (40gr FFFg = 13,300 psi !!!)

Volume is important to pressure - one of the reasons why .50 and .54 are generally pointed to for heavier game - bigger bullet at the same pressure... = more impact shock.
 
theDuck said:
I'm using a Pedersoli Tryon with 1" across the flats.
I have a blackpowder book from the 1970's that gives max loads of around 200-250 grains for muzzleloaders. I wouldn't!!
The Parker Hale repro Enfields from the 1970's have a load of 96 grains of powder for a 560 grain Minnie ball they are 58 cal. so I don't hesitate to use the load I do. Musket barrels are thiner than what I use on my Tryon.
Click to expand...

The 96gr for the PH Enfield is about right: T/C maxi 555gr, .58 Goex FFg 90gr=10,200psi (32" 1:48)

Lyman minie @ 566gr, Goex FFg 110gr=10,000 psi, same barrel

but you're pushing the Pedersoli a bit...
 
So in other words, stick to patched round ball in this gun if I want anything like acceptable velocity, somewhere between 60 and 70 grains FFg is the max I should try for.
 
Gentlemen:

There is nothing that I like better than a good discussion about black powder shooting. If I may add my observations here and some rules of thumb that may be helpful. If you are already familiar with these just bear with me, and feel free to contribute. Most of my experience is with 50 cal projectiles, both conical and round ball, pyrodex and a little real bp thrown in for good measure.

Generally speaking, when I was competing I use the following as a guide:

1 in 60 twist or slower with dealer rifling - Dedicated round ball gun

1 in 48 twist - also known as the combo twist, can use both conical and ball

1 in 36 or faster with shallower rifling - dedicated conical gun.

Now this being said, the rule that I always adhere to it that each black powder gun is a rule onto itself, and the only way to find out weather or not general rules of thumb applies is to experiment, and keep detailed notes, so that when you do find that wining combination you can refer back and see how you got there and duplicate it. I can not stress enough, memory is an incredible poor substitute for proper notes.

Now with the above in mind, I thought my 50 carbine (24" barrel) with a one in 60 twist would not shoot conicals at all.

Well I stumbled on a good deal on a Lee 385 grain modern Mine mould, and I cast some up and lubricated them with my special lube I like to call “Grizzly Jiz” and proceed to shoot them.
Darn-it if I did not get 4" groups at a 100 yards with no key-holeing or oblong entry holes (all of which are signs of bullet instability).

I hope this helps, and if you have any further questions, I would be happy answer them as best I can.

Regards and all the best

R

PS: Make sure that you read nessy’s link, I have used it before and there is a tremendous amount of good info there
 
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