Powder burn

[Brian G]

Talk about complete vs. incomplete powder burn. I am loading 308 with R-17 because it's all I can get. The rounds group well but with huge flame out of 20" barrel. Does this mean that I am loading too much and the extra powder is just wasted? Is there a point, within safe parameters, when more is inefficient? Can a barrel only burn so much?

 

[DocB]

Brian,

Different powders have different flame/flash characteristics which depend in part on the barrel length. You can minimize the flash of the short barrel by using a faster powder or a low flash powder such as the VV powders.

YMMV,
DocB

 

[Brian G]

Thanks, does a big flame necessarily mean inefficient powder burn?

 

[bigedp51]

What bullet weight, powder charge, I have Quickload and can get percent of powder burned.

 

[Brian G]

Thanks bigedp51. Bullet weight is 165 Hornady Interlock SPFB. I did a ladder from 45-49.5. Flame was noticeable at about 47. So lets use 49 grains of RL -17. I know it's not ideal for 308 but, I'm beggin' for powder.

 

[bigedp51]

Brian G

Below is percent burned for RL17,RL15 and H4895, at the Alliant web page they list RL17 with 165 grain bullets. The flame/blast you see varies with powder type and additives, BUT the slower powders still produce the highest velocities in shorter barrels. If you want to see a REAL muzzle flash then reload H110/W296 in a 4 inch .44 magnum. It just goes with the territory and shorter barrels, I have a 30-30 Winchester Trapper Model with a 16 inch barrel and it spits fire with increased blast and at the range people setting next to me think is a 300 Winchester magnum and give me dirty looks.

You can cut down some of the flash and blast by using magnum primers, RL17 is a double base powder and has more deterrent coatings to lower peak flame temperature and a little harder to light off.

Quickload percent of powder burned,(estimated chamber pressure 52649 psi)
47 grains RL17, 18 inch barrel, 95.69% burned
47 grains RL17, 20 inch barrel, 96.61% burned
47 grains RL17, 22 inch barrel, 97.32% burned
47 grains RL17, 24 inch barrel, 97.88% burned

Quickload percent of powder burned,(estimated chamber pressure 52438 psi)
44.1 grains RL15, 18 inch barrel, 95.96% burned
44.1 grains RL15, 20 inch barrel, 96.79% burned
44.1 grains RL15, 22 inch barrel, 97.43% burned
44.1 grains RL15, 24 inch barrel, 97.94% burned

Quickload percent of powder burned,(estimated chamber pressure 52457 psi)
42.4 grains Hodgdon H4895, 18 inch barrel, 97.21% burned
42.4 grains Hodgdon H4895, 20 inch barrel, 97.9% burned
42.4 grains Hodgdon H4895, 22 inch barrel, 98.42% burned
42.4 grains Hodgdon H4895, 24 inch barrel, 98.81% burned