2F vs. 3F?

[Cosmoline]

I'm still trying to figure out some of the oddities of black powder shooting. One I've run into is the fact that while most factory manuals suggest 2F as the default powder for any rifle .50 and larger, a lot of people on line suggest they're getting better accuracy from 3F. Assuming accuracy does improve with 3F, why wouldn't that be the choice over 2F? Does 2F offer better humidity resistance or something?

 

[OFT]

FFg burns slower and has less pressure than FFFg. Velocity is a little slower with FFg than FFFg using the same load. FFFg might give a little better accuracy in large bore rifles with milder loads but I think that FFg would be better with hunting loads. Also FFFg burns cleaner so that may keep shots a little more accurate between cleanings.

 

[Omnivore]

Any of the BP loading charts I've seen list both 2F and 3F for 50 caliber rifles. As stated above, they also list lighter charges in 3F. The heavier charges are always 2F. As with all things, experiment to find what you and your rifle like the best.

As a very general rule of thumb, the hevier the projectile, or the heavier the charge, the higher the pressure. Higher pressure in turn results in higher temp, which in turn results in faster burning of the powder. At some point your gun blows up. Hence you tend to want a slower burning powder for larger and/or hotter loads, so as to avoid overpressuring the barrel. Something like that. Due to the miricales of chemistry, in modern powders we have a huge range of controlled burning rates. In BP we mostly only have granulation differences.

A very similar concept applies to internal combustion engines-- the higher compression (translation - hotter burning) engine needs a slower burning fuel to avoid the wild pressure spikes (knocking) in the fuel charge.

 

[sharps59]

Ok as stated 3fffg is hotter than 2ffg and is cleaner.
my musket 58 cal likes the following loads
goex 3fffg 42grn
2ffg 48grn
swiss 3fffg 38grn
2ffg 42grn
and swiss is a lot cleaner.
I am also told but can not prove it that 2ffg not being as hot will give you less gas etching
2ffg is all i have been using in my sharps. but have been playing w/ the 3 fffg lately. but have found i need the same or more power to get it to group and has more felt rcoil. so its back to 2ffg.

 

[RecoilRob]

Have been going through the same questioning in preparation to loading up some 577-450 MH ammo.

Have come to the decision to use 1F for a variety of reasons. You can use more of it for the same amount of pressure generated..which fills the cartridge better and lessens the fillers required.

Slower and cooler burning powder allows the lube package to survive the entire trip down the barrel. Many have reported that 2FG caused the barrel to lead in the last few inches as the lube burned/ran out.

How it matters in a muzzle-loader? Probably not as much as a cartridge gun...so long as you don't overload it.

 

[RoaringBull]

I think it would be safe to say, just try them in your longarm and see for yourself which one it likes. BP rifles are more picky than most women, but when you fin d what they like its alot easier living with them.

 

[Ifishsum]

I use 3f Goex for PRB shooting in my .50, mostly because it's a bit cleaner and accuracy is a little better. I use 2f with the heavier conicals, for the reasons Omnivore stated.

 

[mec]

I haven't done much comparison in my Lyman 50 caliber great plains rifle but here's what I got with lead ball.
80 Grains Goex FFg 1576fps 965 f/lbs
80 Grains Goex FFFG 1583 973

not much difference.

good bit more difference from a 50 cal plains pistol
40 grains goex ffg-681 fps/ 40 grains goex fffg-884fps.

 

[Wildfire]

PSI curve.

Hey there;
I had the same question years ago. So I called the maker of the gun (at the time) and they said that It was all to do with the PSI curve of the faster burning powder.
I since have used Pyrodex "P" in my .50 cals and have had much better groups since.
I still use "P" in my Encore. 80 grains. Works very well and is extremely accurate in my rifles. I was also told that 110 to 120 grains was a MAX load.
I do wish to find out. 80 grins will put all my shots in 1/2" groups Ceter to center) at 100 yards. This is from 2 different Encores. And was the same load used for the rilfes before that.

The makers testing showed more consistant PSI curves with the Pyrodex "P".
This may explain the accuracy ...
For mor einfo on this exact subject I have in the past posted my loads and results. Should not be that hard to find on here.

I am a complete accuracy nut and will not tolerate a load or rifle that will not perform. If I want a head shot at 100 yards I know the rifle will do it.
And it has many times.