BP vrs Smoke-less

[Marshal Deadwood]

If you down loaded ,,,say big 'buffalo rifle' rounds with BP, you use fillers, wads,,ect,,,,to take up the space.

Why do you not have to use fillers/wads,etc,,,to take up the air space if you have a smoke-less load that leaves space in the case ?

I have a bud that loads some 'recreational plinkin' loads in his 45-70 with Trail Boss and there is a mile of space in the case.

Why the difference ?

MD

[Dick Dastardly]

Smokeless powder doesn't have to be compressed or held tight to the primer like Holy Black does.  But, that said, I've seen shooters elevate their rifle and shake it a bit to be sure the powder in the less than full case was back next to the primer when they pulled the trigger.

FWIW, my best smokeless loads come with nearly full or even compressed powder charges.

If you chronograph some of those loosely filled smokeyless loads you may find that they have velocities all over the map.  Doesn't always happen, but it sure nuff can.

DD-DLoS

[Springfield Slim]

That's sorta like asking why can't I run diesel in my gas car and vice versa. Because they are made up of two different materials with different properties.

[Marshal Deadwood]

Why do you have to worry about bp 'ringing' the chamber,,,but you do not have to worry about smoke-less 'ringing' the chamber ?

An explanation would be appreciate. I do not shoot diesel in my guns.

MD

[Dick Dastardly]

Black powder actually burns hotter than smokeyless powder.  If by "ringing" you mean throat erosion, black powder can do that quicker than smokeyless.  If you mean pressure expansion, I'd be more concerned about some inappropriate smokeyless powder load doing that.  If you are talking about "ringing" done in muzzle loaders, that's another question entirely.

Black Powder burns better/smoother/more consistently as a generality when it's compressed under the bullet.  Air space under the bullet in black powder loads has caused unsafe erratic pressure questions.  So, as a generality, compressed loads are recommended.  There have been exceptions in factory loaded black powder ammo.  I suspect that that ammo had been thoroughly tested before it was released to the public.  Just because there has been some factory ammo loaded with black powder with less than a compressed charge doesn't automatically indicate that it's a safe general practice across the board.

Now, that clear as mud?

DD-DLoS

[Boothill Bob]

I use to load my 45:s with the shotgun powder leftovers when I´ve loaded BP. I put 4,2grn in the case and a paper washer so the powder will stay in the bottom, then I get even loads...

BTW BP RULES

[john boy]

Why do you not have to use fillers/wads,etc,,,to take up the air space if you have a smoke-less load that leaves space in the case ?

Why?  Because with powder charges of nitro based powders, wads and fillers increase Pressure!

[Springfield Slim]

To get a better answer maybe you should ask Birdshot over on the SASS wire, I believe he works for a powder company. All I know is, BP is considered an explosive and smokeless is not. I'm surprised John Boy didn't have a link to a very good explanation.

[Springfield Slim]

Try this link. 
http://www.ctmuzzleloaders.com/ctml_experiments/bulge/bulge.html