Burn rate, Fast or Slow

[sbb]

Boys and girls, what burn rate powders do you use and what is your reasoning for your choice? Is there an advantage using a fast burning powder or a slow burning for 230 gr. lrn in .45 acp? My loads will be used primarily for punching paper. At present I am loading 4.7 gr of IMR 700X that has an estimated 800fps with the 230 gr. bullet. I invite your comments.

[WildBill]

I have always used fast burning powders for target loads [punching paper]. They have always been accurate and have lower residue. Depending on the price of a pound of powder, they can be cheaper on a per load basis.

[foodawg]

I try to use a powder that will fill the case as much as possible for the round that I'm shooting. So this generally means that the shorter the cartridge, the faster the powder.

I also like to compress the powder a little.

I found that by filling the case as much as possible and compressing it a little, I got greater consistency in the velocities, accuracy, and pressures. (I'm one of those geeks that has actually used a pressure barrel hooked up to a laptop.)

[Footpounds]

I've had good results with Bullseye....a very fast powder. It has been used in billions of .45 ACP loads over the decades.

[Mike1951]

I've had good results with Bullseye....a very fast powder. It has been used in billions of .45 ACP loads over the decades.

Bullseye is an excellent powder. But I always caution folks to take extra efforts to make sure a case isn't double charged.

Where with some of the bulkier powders, a double charge would overflow the case, a case might hold 3-6 charges of Bullseye before overflowing. Just saying that for comparison, as no one is going to make that large of a mistake.

But a double charge of Bullseye can be hard to spot and can have catastrophic effects.

I would say that this would be more likely to happen when multiple cases are held in a loading block and the reloader is distracted.

Not so much chance of happening with a progressive.

[Keith B]

I've had good results with Bullseye....a very fast powder. It has been used in billions of .45 ACP loads over the decades.

Bullseye is an excellent powder. But I always caution folks to take extra efforts to make sure a case isn't double charged.

Where with some of the bulkier powders, a double charge would overflow the case, a case might hold 3-6 charges of Bullseye before overflowing. Just saying that for comparison, as no one is going to make that large of a mistake.

But a double charge of Bullseye can be hard to spot and can have catastrophic effects.

I would say that this would be more likely to happen when multiple cases are held in a loading block and the reloader is distracted.

Not so much chance of happening with a progressive.

on the being careful with Bullseye. When I was reloading years ago, the only double charge I ever had was because I couldn't tell there was too much powder, even being VERY conscious about double checking. Luckily, I was trying out some lighter loaded .357's out of a Ruger Security-Six with a solid frame and a a top strap like a railroad tie. Had it been in my model .66 (ala side plates) it would have probably warped one of them. It still left a nasty hammer cut in between my thumb and forefinger from the recoil as it slid back in my hand.

[Footpounds]

Definitely good points on the double charge precaution! After I charge a case with powder, I move it to the FAR side of my table. The "charged" area, if you will. Then as an extra precaution, before seating the bullets, I will shine a flashlight into the cases to make sure that all powder levels are the same.

[ghostrider]

I tend towards faster powers for semi-auto calibres and slower powders for magnum revolver calibres. 9mm luger is an exception - I use bluedot for that. 45ACP seems to work well with various powders (HS-6, WW231, N240). I'm currently using green dot, which works quite well and burns clean, but there isn't a lot of load data around.

[lrb111]

I tend towards faster powers for semi-auto calibres and slower powders for magnum revolver calibres. 9mm luger is an exception - I use bluedot for that. 45ACP seems to work well with various powders (HS-6, WW231, N240). I'm currently using green dot, which works quite well and burns clean, but there isn't a lot of load data around.

What kind of load data do you have for the Green Dot and Blue Dot? I have a bunch of each and have never used it, but I'm looking forward to it.

[ghostrider]

>What kind of load data do you have for the Green Dot and Blue Dot? I have a bunch of each and
>have never used it, but I'm looking forward to it.

I'll have to look up what loads I'm using with green dot. With blue dot I'm loading 7.5gr under a
124gr bullet in 9mm.

[ghostrider]

200gr JHP over 5.6gr of green dot. I also find it makes a good target load in 44 mag.

most data comes from Alliant's web page.

[shu246]

My understanding is:
..Smokeless powder burns more efficiently as pressure increases. Higher pressure means a cleaner burn, no unburned flakes thrown out the front. Also means enough pressure to expand the brass case against the chamber wall and seal against soot blowing back; cleaner ejected cases.
..So look to achieve and keep a high pressure during most of the burn - without, of course, exceeding the SAAMI max pressure at peak.
..Heavier bullets, other things being equal, cause higher pressure because they accelerate slower and delay opening up the combustion space in the barrel.
..Surface hardness of bullet (swaged lead < cast lead < copper jacket), other things being equal, causes higher pressure because friction in barrel also delays opening up the combustion chamber volume.
..Bullet-to-barrel contact area (round nose < full wad cutter), other things being equal, likewise increases friction and thus causes higher pressure.

So, pick the bullet and muzzle velocity you want, then look for a powder which will give you high pressure without exceeding SAAMI max pressure:
..For targets, a light swaged lead bullet at 900 fps will hold down the cost of bullets and keep recoil low; a fast burning powder will reach peak pressure early, completing most of the burn before the bullet exits.
..If you want expansion of bullet cross section in terminal contact, you will need a higher velocity; higher velocity, while avoiding barrel leading, in turn means cast lead with gas check or a jacketed bullet; a slow burning powder will have a pressure curve that rises slower in time, keeping pace with more slowly opening combustion chamber volume without exceeding max pressure; much of the burn may continue after bullet leaves the barrel.

I have heard said, and have no reason to disbelieve, that regardless of barrel length slower burning powder yields increased velocity. With a snubby, you still get more bullet velocity with slower powders - along with more muzzle flash.