Dennis:
The way I understand it, powder burns more consistently when it is ignited in the same place inside the case every time. A charge that doesn't fill the case has empty space that may be positioned differently each shot.
I've read that match shooters used to point their rifles up in the air, and then at the target, so the powder would hopefully end up the same way inside the case for each shot.
Also, when using light charges of slow burning powder in a large case, you can get the SEE. (Secondary Explosive Effect) which can ruin your day.
So, it is both an accuracy, and a safety factor. I think most people like to have a powder charge that will come close to filling the space, from maybe 80% on up in a normal situation. It can be an indication that you've chosen the proper powder type.
I'm sure that others on this forum will be able to elaborate, and perhaps explain it better than me. I'm hoping they will, because this is more important than it would appear to be at first glance.
Thanks for the info. The reason I asked this question is because I was looking throught my Nosler #5 reloading manual at load data for 7mm Rem Mag, 160gr loads. Most powders listed show load densities of low 60's to mid 70's. The H870 is the only powder that has 94-99%. A lot of the posts I've read in here regarding this caliber say the RL22 powder is extremely good but it's LD is 73-78%. Should this be a concern?
If the load is listed in the manual, and you stay within the range of charges shown, it should be OK. But of course you will work up carefully to the max load.
My Nosler manual #4 shows a max of 63 grains of R22 at 78% of capacity for the 160 grain Nosler Partition.
The max load of R19 for that bullet is 61.5 grains at 76%, and it has the asterisk for the most accurate load. Both are close to 80%
The "maybe 80%", I mentioned was not meant to be a hard and fast rule.
Theoretically, a fuller case is the more accurate load.
If you already have R22, why not use it? I use H 1000 in my 7mm Rem Mag, with the heavier bullets. It more nearly fills the case.
