Longer OAL = lower pressure?

[fiscus]

Is there any rule of thumb to how much faster you can run a bullet out of a longer case than from a short one while maintaining the same pressure and bullet weight? [example 45 colt vs 45 acp brass].

[475/480]

NOPE . NO formula.

Sean

[richbug]

I agree, NO formula.

I use 40 S&W brass to load 10mm level loads for my long throated 40 S&W. 95% of the time things work as I would expect. The other 5% is when it gets exciting. Use a chronograph and watch your primers.

[HeavyMetal]

Not only no formula but the strength of the firearm in use is much more of a determining factor than OAL of the loaded round.

I will also add that without a little more information on what you are trying to achieve good suggestions can't be made.

So tell us what you want to do and someone here has tried it already, I'll bet, and will let you know how it worked if it worked.

[dsmjon]

HeavyMetal's last sentence is 100% correct. With one exception. There is a fella on here that goes by "lucky", do not listen to ANY reloading advise he may offer you. If you havn't met him in person, he's a great guy to hang out with. Awesome sense of humor, always has a story to tell about shooting this, or loading that. Something about his lack of eyebrows, the eye patch, and 6 missing fingers tells me not to listen to his reloading advise though...

[fiscus]

I'm trying to figure out a good load for an old belgian revolver from around 1890. Its in .450 caliber, bore slugs at .455".

According to wikipedia it was originally used with a 225grain hollow base bullet and 13 grains black powder at around 650fps, with a 1.1" OAL.

My cylinder is long enough to go to 1.2" OAL or so, and I'm trying to figure out which bullet to try, 200, 230 or 265 grain?

The original loads were made pretty short.

http://img143.imageshack.us/img143/8136/adamsm.jpg
http://img97.imageshack.us/img97/6195/4552i.jpg

[dsmjon]

Start low and work your way up, the best 'universal' advise.

[GLynn41]

sometimes seating out --does not work at all-- --it takes certain amount of powder to get x pressure--increasing the space --one increases the powder but sometimes all it does is get you the same x just with more powder -- nice 6 gun certainly start low and be careful as it does not appear to be a hot rod

[Edubya]

Sure is a nice looking pistola. If I were going to load up something for such a nice looking (possibly a collectors) weapon, I think that I would first off locate a professional, might start by calling up the powder companies. That bullet doesn't look all that different from a .38 special, 130 gr hollow butt WC that achieves that velocity with 3.0 BE.
EW

[fourarmed]

There is a general rule regarding case capacity and potential velocity. PROVIDED THAT ALL OTHER FACTORS REMAIN THE SAME, the potential maximum velocity increases at one-fourth the percentage that the case volume increases. So a 20% increase in case capacity is going to permit about a 5% increase in velocity if pressure, bullet weight, barrel length, jump to rifling, and maybe the phase of the moon remain the same.

[pdawg_shooter]

There is a general rule regarding case capacity and potential velocity. PROVIDED THAT ALL OTHER FACTORS REMAIN THE SAME, the potential maximum velocity increases at one-fourth the percentage that the case volume increases. So a 20% increase in case capacity is going to permit about a 5% increase in velocity if pressure, bullet weight, barrel length, jump to rifling, and maybe the phase of the moon remain the same.

+1 on this rule. It has proven to be real close in the past.

[yondering]

There is a general rule regarding case capacity and potential velocity. PROVIDED THAT ALL OTHER FACTORS REMAIN THE SAME, the potential maximum velocity increases at one-fourth the percentage that the case volume increases. So a 20% increase in case capacity is going to permit about a 5% increase in velocity if pressure, bullet weight, barrel length, jump to rifling, and maybe the phase of the moon remain the same.

I think this is just for smokeless powder though. It wasn't clear to if the original poster is using black powder or smokeless? With black powder, shouldn't the bullet be seated deep so there is no air gap over the powder?

[Larry Gibson]

That seems to be the basic question; smokeless or black powder?

Larry Gibson

[runfiverun]

definately no gap between the boolit and powder with b/p.
i would go with similar case volumns like the 450 adams or webley.

[Mohillbilly]

I'd use a wonder-wad over B.P. two or three if I wanted to reduce the load, or maybe C.O.W. I still like pyrodex because it will compress and B.P. won't... Old iron, I would not press my luck and use smokeless. If ya need more power get a bigger hammer........

[fiscus]

My original intention was to use small loads of unique powder, apparently it works well for low pressure loads. Does a longer case of black powder make more pressure or just a longer burn?

[yondering]

Unique is really smoky at low pressures. In fact, if the pressure is really low, it will start to smoke like black powder, only not as much. Not sure it's the best choice for what you want, but I don't have any better suggestions either. I'd be extremely cautious using any of the fast pistol powders, like Bullseye, Red Dot, Clays, etc; you could damage that old gun in a hurry if you aren't careful.