300WM 166HH Alliant 4000MR?

Not 4000. I load RL23 in my dads 300 win mag with great results.
166 sledge/shock hammer at 3350 no pressure
 
There is data for Ramshot Hunter that would be similar. I think you are going to tell us how it works!
 
4000MR burn rate is between RL-19 @ RL-22 a lot slower than 4350 closer to 4831. i have used it in 3-4 different cartridges but not the 300WM.
 
Straight from their site, here ya go:

4000MR 300WM.JPG
 
I have found 4000MR to have a similar burn rate as RL19. The burn rate list in the Hornady manual places 4000MR between RL19 & H4831. 4000MR is a good powder for many cartridges; I have used it in the .22-.250, .243, 6mm Rem, 6mm AI, 6.5-06, & 300WM. It has less density than other ball powders and provides a better case fill with less empty space. 4000MR velocities are often the highest listed for certain cartridges & bullets. Made by General Dynamics in USA. double base with NG.
 
don't trust that bure rate chart. the one on Ramshot website has it slower than RL-22 and don't trust that one either. Alliant powder responded on another forum and said it was between RL-19 and RL-22 just because of the confusion of the burn rate charts.
 
don't trust that bure rate chart. the one on Ramshot website has it slower than RL-22 and don't trust that one either. Alliant powder responded on another forum and said it was between RL-19 and RL-22 just because of the confusion of the burn rate charts.
That's a big difference!
 
Burn rates can vary greatly from chart to chart.

Some of my 4000MR loads:

.243 Win - 42.5 gr with 105 grain bullets, 45.5 with 87 grain bullets,
.22-.250 - 36.0 gr with 75 grain bullets
.300 WM - 70.5 gr. with 178 grain bullets

These are close enough to those of RL 19 - so - "I have found 4000MR to have a similar (resembling without being identical) burn rate as RL19."

I don't pay much attention to powder burn rate charts because methods are not documented. Detailed evaluations/comparisons would be next to impossible because of the large number of variables. Read your friendly manual, apply common sense & go from there.
 
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