Load for 45.cal?

[tg]

For starters I always figured from bore size in grains to 1 1/2 bore size to start out, for yours it would be 45gr to 68gr these are fairly lightloads even at the top end, check the manufacture for the limit at the high side and work from the 1 1/2 load up till you find the best group, it would not hurt to go down from the starting point in increments of 5gr some guns with shallow grooves like the lighter loads best.

 

[longcruise]

I do measure it by volume. When did I say I measured it by weight? I've been told that when using pyrodex, use 10 grains less than what you would when using BP. A powder measurer normally goes up in five grain increcements

All my chrongraph testing of Pyrodex RS and Goex ff have showed them to be near identical when thrown from the same volume measure. Near identical as in only about 25 fps difference :shocked2:

Pyrodex P (pistol) is probably pretty close to Goex fff but I have no data to compare it.

So, short answer, treat your pyrodex like it was regualr bp. You probably don't shoot Goex over there but hair splitting is usually fruitless in the ml/bp world.

 

[bwhoffman]

25 meters, close to 25 yards!
volume for volume, I would try 25 to 30 grains by volume just for kicks!
I have shot my .50 with 30gr and 25 yard target groups were outstanding!
of course, at longer distances that load is going to drop a tad faster then a more substanial loading.

 

[Zonie]

With everyone understanding that when I say "grains" here I am speaking of grains as measured by volume using a suitable black powder powder measuring device I'll give a few numbers out of the 2nd Ed of the Lyman Black Powder Handbook and a .45 caliber gun shooting patched roundballs.
The barrel has a 1:48 twist so the pressures will be a little higher than your smoothbore .45 will have.

GOEX Black Powder, 3Fg:
40 grains = 1324 FPS (Feet per Second), chamber pressure = 5,400 PSI (Pounds per Square Inch)

50 grains = 1469 FPS, 7,600 PSI
60 grains = 1614 FPS, 9,800 PSI
70 grains = 1691 FPS, 11,100 PSI
80 grains= 1768 FPS, 12,300 PSI

PYRODEX P

40 grains = 1471 FPS, 7,400 PSI
50 grains = 1604 FPS, 9,200 PSI
60 grains = 1738 FPS, 11,100 PSI
70 grains = 1864 FPS, 13,800 PSI
80 grains = 1990 FPS, 16,500 PSI

This information seems to indicate that at the Pyrodex does generate higher pressures and corresponding higher velocities for a grain to grain comparison.

As for safety, your .45 caliber gun should be able to withstand any of the pressures indicated above with room to spare.

 

[longcruise]

GOEX Black Powder, 3Fg:
40 grains = 1324 FPS (Feet per Second), chamber pressure = 5,400 PSI (Pounds per Square Inch)

50 grains = 1469 FPS, 7,600 PSI
60 grains = 1614 FPS, 9,800 PSI
70 grains = 1691 FPS, 11,100 PSI
80 grains= 1768 FPS, 12,300 PSI

Those numbers don't jive with my chrono!

One thing we have to remember is that Goex powder has been all over the board as far as consistency is concerned. I had some from an early 90's lot that was around 20% less in velocity than the current stuff.

Those books are handy, but there is nothing like shooting your loads over a chrono to open your eyes.

Roundball has some current .45 cal chrono data. Maybe he will post it?

 

[erzengel]

The powder measurer are by volume though there are written in xy grains at the marks.

When I wrote 30 grain, that refers to the mark on the powder measurer saying 30 grain which is arbitary as it is a volume.

 

[Zonie]

marmotslayer

I agree that using a crono will give the best information about a particular barrel, patch, ball and powder load.

My reason for posting that information was to give Duke some information about breech pressures, comparing real black powder with Pyrodex P.

Duke was mentioning some concern about pressures and the need to reduce the load volume when using Pyrodex in his gun.

My intent was to show that with the small volume loads he will be using the pressure issue is pretty much a moot point because his gun is built to withstand the high pressures developed by the 70 and 80 grain loads.
Using Pyrodex in smaller loads will not begin to approach these 70 and 80 grain loads.

The velocity values of even the light 40 grain loads will support the idea that the ball will definitely poke a hole in a target, or anything else the ball happens to hit. :grin:

 

[longcruise]

Hi Zonie,

Hey, I wasn't questioning or critiquing your post. Just adding another dimension to it.

Unlike H4831 that will give repeatable results from can to can and lot to lot, our BP (especially Goex) has been shown to be all over the board.

 

[paulvallandigham]

I have written this before. Using a chronograph, I have learned that screening your powder to get the fines out of it will give more uniform patterns and velocities(SDV) in a BP gun. NMLRA rules will not allow shooters to plug their vents on their flintlocks, when they load their powder, and PRB. Leaving the vent open will allow fines to be blown out the barrel. This changes the amount of powder in your barrel, and therefore the velocity varies widely, too. Use 2Fg powder in flintlocks, and screen the fines to get lower SDV, and better groups.

This generally does NOT happen with percussion rifles, as the orifice in the nipple is too small to let any but the very finest of fine pieces of powder to exit through the nipple. Use 3Fg in percussion rifles, but screen out the fines. Since powder charges in percussion rifles shoot the most consistently when the powder is compressed, leaving fines in the powder gives uneven compaction to the load, and wider SDVs.

The Before and After testing shows these anomalies are happening in both types of guns as I have described. None of these will affect the casual shooter, or plinker, and I don't bother screening powder I use for these purposes either. But, if small groups are needed, this added step to handling the powder produces good results.