Ok I have a Savage 110FP in 300WM. It has been awhile since I have loaded up any ammo for it. I was using Winchester WSM (or maybe WXR) powder with 180 gr. Speer SPBT bullets & also 165 gr. Speer SPBT bullets, CCI Magnum primers and the same brass from the same lot in both loads. Now my question is this, what would make the 180 gr bullets hold a much tighter group than the 165 gr bullet? On both I started seating just off the lands (the 165 was not long enough) and worked all the way back to the COL. The 180 gr at COL can hold .5-.75 in group at 100 yards but the 165s open way up. I have a Lyman manual that says this is a common problem with lighter bullets in the 300WM, something about jacket thickness, velocity and pressure deforming the bullet. I have heard of many people getting excellent accuracy out of the speer 165s in a 300WM. Could it be that I might have to switch to a little faster powder for the lighter bullet? I appreciate any help anyone can offer and I appologize for the lack of detailed information. I have not touched my reloading equiptment in about 6 months, but this was one of the things I was working on before it went into storage. The whole reason behind this is that a 180 gr bullet is overkill for a Whitetail in Louisiana.

For the lighter bullets, many people have had good luck with IMR4350. I personally haven't had good luck with the lighter bullets. You go to the 180, 190, and 200 grain pills and I bet your rifle will settle into something there. RL22, H4831, and H1000 I feel are the best powders for those bullet weights, though I have never tried IMR7828 (many guys like it). First load to try is this:

74-77 grains RL22 and 180 grain bullet (180 nosler partition or 180 accubond).

Then, if that combo doesn't work, try other bullets and the powders I had mentioned. My guess is your rifle will like RL22 with 180 grain bullets. However, my first 300WM did not. RL22 with 200 grain partitions and sierra gamekings were the ticket.

I used to shoot 168 Sierra match bullets with excellent accuracy out of the .300 Win. Mag. I used Winchester cases, Reloader 22, and Federal 215 primers for 3207 fps.

Many .300 Win. Mags. shoot 150 gr. bullets very well, but as has been stated, IMR 4350 is usually the powder of choice with this bullet weight. I think Reloader 22 is too slow for 150 gr. bullets in the .300 Win. Mag. in order to achieve top velocities.

Not all rifles like bullets of as certain weight, especially combined with certain powders.

One more opinion, and I'll shut up. Quite honestly, I don't see any good reason to shoot bullets lighter than 180 grs. out of the .300 Winchester for any reason, even for deer hunting. I use the 180 gr. weight for all game, from whitetail deer to moose plus all sizes of African plainsgame up to 2000 lbs. in weight, and I have seen no good reason at all to go with the lighter bullets, and yes, I've tried 'em. The lighter slugs might start out faster, but the 180s do everything better down-range, out where the game is........

AD

Thank you for your all the help. I have a good 180gr load, but I am always willing to try other combos. I would love to stick with 180gr for all my hunting needs but the average whitetails down here in Louisiana are not nearly as big as northern whitetails. That is why i really don't want to use the 180gr. I do have relatives in Michigan that I hunt with and would have no problem using a 180gr bullet on the whitetails up there. Anyway on a positive note my rifle is a savage and making it a switch barrel is very simple. Was thinking of getting a .270 or .243 barrel for it. That right there would solve the bullet wieght problem. But again thank you for the info on the loads I will certainly have to try them out and maybe in the process I could figure out a nice load for the 150-165gr in the 300WM.