primer ?

[Catfish]

There is reall no way to tell what the presure is going to be till you try, but it could jump a bunch. I ran some primer test with in my .22-6mm with H-870 powder and fired different brands of primers in both regular and mag. I got less than 100 fps. varation between all of the primers. In the same rifle with Mag. Pro powder I switched from Win. mag. primers to Fed. match mag. and the velosity jumped over 200 fps. and the presure became excesive. 1st. rule, be safe.