Re: How does 220-grain .300 WIN MAG compare to 190-gra
It helps to know, but is not 100% necessary. I can load up test ammo to standard COAL (cartridge overall length), and vary the powder charge to find a good load. Typically I will send test loads with 5 rounds each in 5 groups (25 rounds). Each load will increase in powder charge from the next one. Shoot for groups until you find one your rifle likes. For the 300WM, I'd recommend testing the loads at a minimum of 200 yards, and prefer 300 yards. I've tested enough loads with the 300 WM to know where to be at on the powder charge. Each rifle has a similar sweet spot, but they all can vary. So, this is why it helps to tune the load to the rifle. Most groups will shoot ok, or about MOA. Then one or two of the loads will shrink up, and this is your sweet spot. If you shoot them through a chronograph, you normally see the ES and SD decrease for the sweet spot load, also.