Rifle case fill percentage

4

4T4MAG

New member
Is there a benefit to achieving a case fill rate of %100? I'm wanting to load some 338 win mag with Varget, of which Nosler and Barnes show load date. However the fill rate is about %85, where some other powders are %105 full. Does a case only %85 full still burn well? The use will be mainly hunting. I know I could go out and test each load to find out myself, I figure the knowledge is already out there. I tried searching but did not find much.

Thanks.
 
I personally like powders where I get full cases. My best match loads are slightly compressed loads. I get a lot more consistent numbers with slightly compressed loads.
 
I seem to get away with 105% per quickload with stick powder.
Ball powder does not compress enough to notice.
 
Accuracy aside, i have never had any problem with cases filled slightly less than full... you can expect perfectly reliable ignition with an 85% fill, and if that gets you to an accurate MV for your gun, it may be better than a 105% fill of another powder.
 
4T4 Mag,

The slower bullets give the muzzle more time to rise, so some velocity variation doesn't usually affect shot placement much. The old M72 National Match load in .30-06 always ran on about 80-85% case fill, depending on the lot of 4895, and it could stay in the 10 ring at 600 yards (about 12" circle). So, for hunting accuracy that isn't at extreme ranges, I would not be too concerned.
 
I try to stay as close to 100% as possible with some cartridges and powders. But, the choice seems pretty arbitrary, when you look at the particular cartridges and powders where I do such.

Generally, I try to stay with 95% or better, but some loads are down as far as 80% fill (.30-06, .270 Win).

My most consistent loads have always been compressed extruded powders. (Up to 110% case fill .... necessitating a long drop tube.)
 
It is kind of a self-correcting situation. The reason you only get 85% case fill is because the Varget is a little too fast for the 338 mag, but faster powders ignite more easily than slower powders so should not be a problem. If the load you are using to get the 85% fill is within the start to max published loads, then it should work well. You wouldn't want to go with an 85% fill load with a slower powder like RL22, but I doubt the books would have such a load listed.
 
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