Home Forums Reloading Big Game Rifles Christensen Arms Mesa 300 Win Mag Load Development

I bought a Mesa 300 WM from another member here. Really pleased with the feel so far. Haven’t shot it yet but I’m going to be working up a load here soon. Fitted it with a NF SHV 5-20.

I think I’m gonna start with H1000 and 178 gr ELDx. I got the ELDx on sale, kinda pulled the trigger before I really knew what I wanted, I probably should have gotten a heavier bulllet but hey, we’ll see how it goes. I’m also using CCI 250 primers and Jagemann brass.

I have a few other powders to try too, H414, Retumbo.. any recommendations would be great.

H-1000,Retumbo,RL-19,RL-22,RL-25,H-4831,IMR-7828

Yeah H1000 would be a powder I would try here along with H4350, H4831sc and RL22.....Good luck....Hb

https://m.imgur.com/gallery/IMEBidd

1- 77.0
2- 77.4
3- 77.8
4- 78.2
5- 78.6
6- 79.0
7- 79.4
8- 79.8 (not on paper...)
9- 80.2
10- 80.6

Alrighty, shot my ladder today. Started at 77.0gr and worked my way up to 80.6gr with no signs of pressure. #1 was cold bore. Gonna load 5 rounds each for loads 1-6 and shoot for groups. See how it goes.

Recently bought my first 300 win mag. Just finished load development. I spent around 1 1/2 months developing this load. The load I settled on is 180 gr. Nosler Accubonds with 75 gr H4831sc. CCI 250 primers in Fed cases with 3.35 OAL. I researched alot and there are a few good powders I continually came across frequently being H1000, Rel 22, H4831 and H4350. 4350 seemed be most prevalent in lighter bullets like 165gr and down.
I usually used one powder and work with it until I get what I feel is best with it. Then I may start with another powder and do the same. Good luck in working your load and I am very pleased and happy with 300 win msg. Seems be very versatile

RWS OR NOSLER BRASS, 75.4 gr RL22. 180 Accubonds or Barnes 180 TSX. = .268 5 shot groups at 3060 fps. Start at 74 gr and work up!