Hello all i just starting to reload for my 7mm rem mag. I made a dummy bullet by putting in and shutting my action on my gun. should i start there with my loading of lowest mount of powder the seat bullet .010 after that thanks.
Well everyone has a opinion and here is mine, H1000 is to cold for a 7mm rem mag, I'd try them pushed in the lands with H4831sc or RE19. Be careful but fyi every .100" your out on oal over what the book list as max length your going to need 1.5-2 grns more powder to keep up, amount depends on what you do use, but always start a little low.
Well yes but don't start that high, every cartridge/powder combo is different, but if you do use H1000 and your manual says max length is between 3.250 and 3.280" and you are at 3.450" then by the time you get the speed and consistency you want you will likely be 3-3.5grns over max charge but whatever you do (never start that high you can really hurt yourself) start about 1.5grns under max, then work up .5 grains at a time until you see the very first signs of overpressure (cratered primers, then flattened primers, then sticky bolt lift, and blowing primers out completely) don't go past the cratering, once you get to that point back off .2-.4grns and that'll put you in the ball park.
Read a reloading manual or two, will get you started. Still plenty to be learned, I'm still learing after 20+yrs of reloading. Use the most current data, for the powder you are using, thatyou can find.
There are only two seasons: Hunting season, and Getting Ready for Hunting season. -DAD
Your first loading tests should be aimed at finding the max charge for what ever seating depth you wish to start with. We have no more idea of what your rig will accept as max than you do.
Start at the start loads. SLOWLY work up with one round of each charge done in maybe .3 gr steps, until you reach book max OR SEE PRESSURE SIGNS. If you see early pressure signs back off a full grain or more. Once you know what your own max charge is you can start to test for accuracy to find your best shooting charge. THEN you can test that charge at different seating depths to establish the best combo.
I agree that a 4850, or 4831, is likely to give better performance than H-1000 but who really knows?