[Jim, West PA]

I'm using a .457 RB and a .456 220gr. conical.
I have heard that this powder burns much cleaner than BP.

[351 WINCHESTER]

The ROA is the strongest bp revolver ever made. I would start with about 35 grs. for both bullets and see where it hits on your target. It will most likely hit high with the conicals unless someone installed a higher front sight. Don't forget to clean afterwards as 777 is corrosive too even though it leaves much less fouling.

[Jim, West PA]

Thanx. Am to use 35 scale weighed grains ?

[arcticap]

Am to use 35 scale weighed grains ?

Absolutely not.
All cap & ball loads mentioned here are by volume unless specified otherwise.

[351 WINCHESTER]

You need to get a bp measurer as black and their substitutes are measured by volume, not weight. Enjoy.

[Jim, West PA]

Thanx fellas.
Mmm...now what did i do with that measurer ?

[arcticap]

Here's a conversion chart:

http://www.curtrich.com/BPConversionSheet.htm

Or there's empty cartridge cases:

Cartridge Grains
.22 LR = 5
.320 ACP = 7
.380 ACP = 10
9mm = 13.3
.40 S&W = 19.3
.30 cal Carbine = 20
.38 Special = 23
.45 Auto = 26
.357 Mag = 27
.44 Spl = 34
.44 Rem Mag = 39
.45 Colt = 41.6

[AbitNutz]

You can't put enough T7 in it to hurt it. However, it starts to lose consistency if you compress it too much.

[Jim, West PA]

Thanx arcticap, thinkin back now. I used to have a measure jist for this made from a .44 mag case with a small handle soldered to it.
I see that case is missin from yer chart.Spose i'l haftav make me another one.
( i used to know and do all ths stuff years ago and now with theb help of everyone on THR i'm relearning it all)

[Jim, West PA]

"You can't put enough T7 in it to hurt it. However, it starts to lose consistency if you compress it too much. "

Thanx AbitNutz,
I know that 'bout BP but T7 is new to me.
Right now i'm jist stuffin it with 3f simply because i likes all the smoke :D
Aint real concerned with accuracey .(yet)
I'm tryn the T7 coz i hear it's a bit cleaner.

[arcticap]

I used to have a measure jist for this made from a .44 mag case with a small handle soldered to it.
I see that case is missin from yer chart.

These .44 case capacities have been added to post #7 above:

44 Spl = 34
.44 Rem Mag = 39

[Jim, West PA]

These .44 case capacities have been added to post #7 above:

44 Spl = 34
.44 Rem Mag = 39
Thanx articap. That 39grs. exaplains why i had one made form the mag case in the past.
I appreciate your input.

[Pete D.]

Or there's empty cartridge cases:

Cartridge Grains .22 LR = 5 .320 ACP = 7 .380 ACP = 10 9mm = 13.3 .40 S&W = 19.3 .30 cal Carbine = 20 .38 Special = 23 .45 Auto = 26 .357 Mag = 27 .44 Spl = 34 .44 Rem Mag = 39 .45 Col....
That is a nice resource.
The data was derived using Goex FFg. Make note that other brands and granulations of BP may yield different weights per volume. Swiss powders can be 10-15 % denser than Goex.....probably not enough to cause a major safety problem but enough to change performance.
Pete

[Jim, West PA]

The data was derived using Goex FFg. Make note that other brands and granulations of BP may yield different weights per volume. Swiss powders can be 10-15 % denser than Goex.....probably not enough to cause a major safety problem but enough to change performance.
Pete

Good points Pete. Thanx for bringin this up.
When it comes to guns'nat we can never have too much info in our memory banks.

[Gatofeo]

Here's a novel idea: Ask Hodgdon! After all, they're the folks who make 777 and have ballistics labs that can measure pressure. They also have trained personnel to interpret the data.

I would NOT use 35 grains of 777 under a 220 gr. conical bullet.
Hodgdon lists a maximum of 35 grs. under a .457 ball of 144 grains with a felt wad between powder and ball.
And you want to use a projectile that weighs more than half again as much? Not a good idea.
Hodgdon 777 is not a direct substitute for black powder, straight across the board.
All things being equal, you reduce 777 by 15% to get the same velocity that black powder delivers.
Yes, the Ruger Old Army is the strongest cap and ball revolver made, but over-pressure in cap and ball guns is not nearly as recognizable as in cartridge guns. There are no cases to measure, no primers to observe.
Excessive pressure often becomes apparent only after it's beyond the pale, manifesting itself in caps that fragment or shatter, or the hammer being blown back to half-cock. Extreme pressures can blow the hammer back to full cock. This happens, and you KNOW you're in the danger zone.
Ask Hodgdon. It makes 777 and has the lab and people to measure its pressures. Anything else is guess work or worse: "Well, my gun didn't blow up so it must be safe."