BHN and FPS

[Scibaer]

i have some .429 240 gr. BBSWC's  with a bhn of 15 ..
how fast can i push these without leading ?  they have red ( maroon ? ) lube on them, if that matters.

[stimpylu32]

Glenn

I see no reason that you could not run them up to around 1200 fps ( per Hodgdon's data ) , however the size will be more of a factor as far as leading goes rather than hardness .

A properly sized soft bullet will keep leading down much better that a undersized hard one in most cases .

stimpy

[Scibaer]

rich,
ok i know less then i thought i did 
on the hardness scale where does 15 sit ?
 also i thought it would have been the other way round, an oversized bullet would lead more, not a undersized. can you explain that ?
glenn

[stimpylu32]

Glenn

A 15 bhn bullet will fall in about the upper 1/3 of the scale with 6 being around the bottom and 22 being around the top +/- some .

As for the smaller bullet causing more leading , that is because it will allow more gas cutting as the hot gases blow past the bullet and melt the lead , building up in the grooves , were as an over sized bullet will tend to shave lead as it enters the barrel and not build up in the rifling .

stimpy 

[Lloyd Smale]

it mostly is a matter of how good of a gun you have. If it was built with proper chamber and throat dimentions, the cylinder lines up properly with the barrel, the forcing cone is cut properly and and is in good shape and it has a good barrel, the bullet is sized right to match the rest of these measurments and you use a good lube you can push 15 bhn bullets to 2000 fps. without leading. If some of these are not right you will never get there and some guns will lead with about any alloy at any speed. Ive allways had the best luck with accuracy in guns that are built right with harder alloys but some guns that are out of spec will sometimes do there best with softer alloys but then they will never be tack drivers anyway. Another big cause of leading is choosing the wrong powder. Idealy you want a powder that gives its peak pressure about half way down the barrel. So that will vary with caliber and bullet weight and barrel lenght. If you use to fast of a powder you can cause gases to blow by the bullet or cause the  bullet to deform as it enters the forcing cone. Some powders burn hotter then others and it makes them not ideal for cast bullet applications. Now after all of this rambling ill give you one example of an extream. I shoot a 16 inch tc carbine in 3030. I size down 120 lbt lfngc 32 mag bullets to 310 cast of of #2 which is about what your using for hardness. I lube them with my home made lube when i size them and then lube them again with tumble lube. ive shot these bullets at 2600 fps out of that 3030 without any leading what so ever and accuracy is in the 2 inch range at a 100 yards. It took alot of experimenting with powders and primers to find a combination that was kind to that cast  bullet but it can be done.

[Scibaer]

ok i can understand that, it makes sense. i guess i should have been thinking in that direction of gas cutting, hence the need for gas checks.

i didnt really want or need to push the 240's to 2000fps, i just wanted to know if they would lead at what speed and if that was related to thier hardness measure. the powder im using for this work up is HP-38. #17 on the burn rate chart ( if that matters any more the general revelancy )

but i think i got enough of this under my belt to work up these cast bullets, anyhow.
thanks, im sure i'll have more questions later.
glenn

[WayneS]

You didn't say what you plan to shoot these  in ? and HP-38  is pretty fast, chrck yoiu manuals

[Scibaer]

i have a taurus model 44 with a 4 inch barrel.
 hodgdon says 11 grains max of hp-38 with the 240grain swc for 1334 fps with  38,100 cup .. thats a max load