f/s versus grains of powder

[canadianloader]

I am trying to determin how many f/s I will loose per grain of powder.I am using H4350 in .300 win mag 26'' barrel my loading of 74 grains gave me a velocity of 3470 high I know I would like to end up at about 3150-3200 looking for a little input from those of you with a bit more experence than I with this powder and caliber.The load will be used in a H.S precision rifle so I expect accuracy to be good in most loads.

 

[HSMITH]

3470/74=46.9 fps per grain. 305/47= 6.5 grains reduction for the midpoint you are looking for.

This is FUZZY math and i'll give you 30-1 odds that it won't work out over the chronograph exactly, but it is a place to start. The only way to know without a half hearted guess, like the math above, is to reduce and then chronograph.

 

[HiWayMan]

HSMITH is right on with this one. I will assume you have access to a chrony. The math is a bit rough, but it is a starting point. For instance, I found that with a .38 special load an increase of 0.2 grains of Unique would give a rather consistant 30 fps increase. In over 200 tested samples this relationship has held true.

You'll have to experiment on your own, and since you are working outside of published data, caution and double checking everything is your friend.