ORIGINAL: y_not5
my question is when I buy powder does the ffg or fffg matter in terms of saftey if my rifle is rated for 120 grains of loose ffg can I use 120 grains of fffg? my concerns are mainly for my fathers sidekick and my omega z5 I know my omega is rated for 150grains loose or pellets and the sidekick is rated for 120 loose and 150 pellets, but in booth manuals says nothing about fffg, what would my restrictions be if any using fffg insted of ffg or can I use the regulations for ffg for the fffg??????
The different burn rates of the different granulations cause different amounts of pressure and the pressure curve jump is steeper/faster with 3F than with 2F.
The industry standard rule of thumb to manage the pressure differences to approximately the same levels is to reduce the 3F load by 10-15% below the 2F load data.
Example:
Ifa 2F load data is 100grns...just use85-90grns 3F in it's place.
In the specific case of your 120grn example, a 10-15% reduction for 3F would be a max load of 3F in the range of 102-108grns.