I have a 300 WSM built on a 700 Rem. SA. I had this rifle built with a short throat to so I could get close to the lands at the limited magazine lenght of 700 S.A. I had tried all kinds of loads using H4831 and similar buring rate powders with very inconsistent results. Bugholes
one day and 1 1/4" groups the next. So I was looking in the Nosler manual and it said N550 wasa the most accurate powder tested with 180 grain bullets. HMMMMMM, I looked at the listed powder charges and saw they were in the mid to high 50's for the charge. Well a Std. L.R. primer lights that much powder just fine in the 30-06 so thought why not. Got so Fed. 210M's and the 175 Sierra MK. and started loading. At 59.5 gr of N550 and the 210M I hit a load that averaged 2963fps and gives E.S. in the high single digits to the low teens everytime with no pressure signs at all. It shoots in the .3's to .4's everytime if I do my part. Nosler shows IMR 4060 as the best powder tested for the 150 grain bullets so I tried that with the 155 gr.Lapua Scenar again with the 210M and it is showing some great promise. I need to do more testing to prove that it does it consistently but I think it will.

Has anyone else done this, results?

Shoot Safe, Shoot Straight......RiverRat

River, If you intend to hunt in very cold temps...say the teens I would consider the use of a mag primer. I have seen a lot of varied suggestions when it comes the use of mag vs. standard primers in the 300 WSM. A friend gave me a couple of boxes of CCI 250M pre blount and they have worked very well with RL-19. I must have a very slow 24" tube because I am getting nowhere near the Nosler or Barnes posted mvs.
I tried WLRs and WLRMs but both seemed loose in even the new Win brass. For powder Ive shot Big Game, H4350, Varget and RL-19 with the last two giving the best results with light projectiles.
Dave

RiverRat -- I use the Fed 210M primer for my .300 Win mag. I have hunted from 20 below zero up to 95 degrees for 20 years with that combo and never had a problem. I use RL-22 powder. When I tried the Fed 215M primer I blew the group to 1.5 inchs, went back to the 210M and right back to pin point accuracy. When I get above 80 grains of powder with my other Magnum's I do use the Magnum Rifle Primer. Good shooting.

phurley,
Thanks for the input. Its good to hear from a hunter as opposed to a gun writer regarding the use of mag primer...I was only relaying what I had been reading. Thanks again. I have always been a fan of the Fed 210M but when I started loading for my first mag I was told to go with the Mag primers.
Dave