2571 said:
"More is safer but 45 up to 90 . . . "
Please explain. Are you concerned about 'detonation'? I thought that was not a concern with bp.
BP cannot "detonate" under any circumstances.
Most rifles over about 40 will shoot best around 1/2 ball weight of powder. FFF for most bore sizes but FF needs to be tried in bores over 45. Bores under 45 and over 54 change the formula (more on this latter)
Smokeless powder WILL detonate since it has a High Explosive base and it often does with loads that are TOO LIGHT. They are designed, in most cases, to be loaded to 60-75% capacity minimum. Get to far from this and problems can and do arise in both rifles and pistols with certain powders.
Now if FFFF is used in brass suppository RIFLES there can be high pressure spikes, according to a freind who tried in while experimenting with the 357 maximum case (35-30 Maynard actually). This based on weird things happening like flattened primers.
This said BP is limited to about 100000 PSI in CLOSED BOMB TESTS. IE a container that is so thick walled it cannot be burst by blackpowder due to its limited pressure capability.
Powders that can detonate do not necessarily produce extreme pressures but the pressure RISE is so rapid that it breaks the container, be in barrel or whatever. This is how HEs like C-4 can "cut" steel beams. Its the high velocity explosion (26000 fps+) that breaks the steel. Pressure alone would likely just bend it.
Back to BP internal ballistics. BP simply will not produce enough pressure to burst a modern 4140-4150 gun barrel unless very, very thin.
Bore obstructions in this material are extremely unlikely to burst the barrel. Low quality steels often used by ML barrel makers are another matter.
A great many people shoot far too little powder for best accuracy in round ball rifles or even smoothbores. My testing with a 50 caliber smooth rifle found that the SB barrel took 100 gr of FF to shoot well at 50-60 yards. The rifled barrel by the same maker shot very well with 75 gr of FFF.
I have a heavy match rifle in 50 caliber and the barrel maker in testing the barrel before it was final shaped said to use 120 gr of fff. It shot into the same hole at 100 with this load in testing.
Search Sleepy Hill Barrels.
So where to I start? I start at 75 to 90 gr in a 50, 100 in a 54 (around 1/2 ball weight) something than range for a 58-62 and about 120 for a 67-69 then probably go up.
The larger bores, over 62, will shoot well and give decent velocity with about 1/3 ball weight of powder.
40 caliber and under are less efficient and may need more than 1/2 ball weight. Some shooters find 40 cal accuracy loads in the 60-70 grain range. The last load I tried in my 40 caliber using a cloth patched picket was 80 gr of Swiss FFF and it was the best load so far. But Pickets are not RBs.
Now other factors.
The things attached to the barrel that contain pressure may be weaker in one way or another than the barrel steel. The drum and nipple percussion system as made from modern cold rolled steel is scary, the stuff is brittle and likes to break at sharp corners when shocked, like when the hammer strikes the nipple. All breeches need to be carefully and properly fit. Nipple and vent liner threads need to be tapped carefully and with a minimum clearance tap if it can be had and it can be for 1/4-28. Barrel steels are out of teh users control unless he refuses to use barrels not made of certified gun barrel quality steel. These are harder to find in the American custom ML barrel market but surprisingly the Italian imports like Pedersoli and Uberti have, from reliable sources, European standard barrel steels. Something similar to our smokeless barrel steels.
Stainless is another subject and is best avoided since it has a poor track record compared to 4140-4150 in modern rifles.
Dan
