Will the size of the group really change that much with each lot of powder? I am shooting about a 1" group or under consistently with my rifle at 100 yards,I have a .300 win mag Tikka T3 Varmint Stainless. I know this is not anything like the long range shooters on this site shoot, but for the hunting that I do this type of group is fine for me.
Is there any other way to tighten up my group. I am not able to lengthen my shells, because I am limitted by my clip. 3.34" is all I can stretch my bullets out to, which is factory length.
I am using winchester brass, Reloader #19 powder, and federal match grade magnum primers with 168 gr Barnes X triple shock bullets. Any help or advice would be great. I have only been loading my own rifle shells for 1 or 2 years now.
With the restriction of your magazine, I think the only way that you could get tighter groups would be to try a different bullet/powder combination.
A couple years ago I was loading for a friend's 300WM, it was Model 70 Win. With the bullets 50 thousands off the riflings his groups hovered around 3/4". But, the shells wouldn't go into the magazine, so I had to seat them another 60 thousands deeper.
So now with the bullet 110 thousands back, his groups opened to 1 1/2". There's not much else that can be done to improve it, for he wants to use only the 180 Partitions.
I can't agree that everyone should buy big jugs of powder...just get a couple of 1 pounders of the same lot# when you resupply. It's fine to buy what you need but you shouldn't be overbuying....although prices will most likely go up and powder lasts a long time. Still a personal decision for most shooters.