Yesterday, I packed up my MRC 1999, with Lothar Walther (1 in 10 twist) Barrel and McMillan Stock in .300 WSM and took her for her maiden voyage to the range.



With Reloader 19, I started at 70.0 grains and worked my way up to 72.0 grains in .5 grain increments and loaded three at 72.3 grains. I was shooting 150 grain Hornady Interbonds. My results were as follows:



70.0 grains, .75 MOA

70.5 grains, .50 MOA

71.0 grains, 1.00 MOA

71.5 grains, 1.44 MOA

72.0 grains, 2.5 MOA

72.3 grains, 1.63 MOA



I think I found me a winner with the 70.5 grains of Reloader 19 and the 150 grain Hornady Interbond.



I also gave WW 760 a try and it was not pretty at all. I started with 68.0 grains and worked up in .5 grain increments to 70.0 grains and tried three rounds at 70.2 grains. I had only one load, 69.0 grains that had a semi-acceptable level of performance and that was a group of 1.38 MOA. The rest of the groups were 2 and 3 inches.



I was using virgin Winchester Brass that I acquired when the WSM�s first came out and this stuff is incredibly consistant in weight and thickness; neck�s run about .016 inches.



In terms of primers, I always use Federal primers and in this outing I was using Fed 215M�s.



While I was disappinted that WW 760 didn�t work out, I do have a winner in the form of Reloader 19.



I guess one of these days I need to break down and buy a chronograph.



Have others had dissapointing results with WW 760?

30 cal mag fan,
I too have been going round and round with the 300wsm.
I'am using 180gr woodleigh pp's and also 180gr sierra spbt. I have used win 760,imr 4831,4350,,h4831 and rl19. I use win brass and fed 215 mag primers.
My rifle is stock out of the box. When I got it there was a few gliches with it . It shot well, then I was educated to a couple off accuracy issue with the rifle. Before it being tuned these were the best I could get.

win 180 gr ballistic tips 1in
Sierra 180gr w/69.5gr H4831sc .97
sierra 180gr w/64.5gr win 760 .668
woodleigh 180gr w/59.6gr rl19 .52

Now I took the the rifle to a very respectable smith. He then educated me. He did some tuning of the rifle.
So I loaded up some of the 63.4gr of rl19 and went to the range. It did exactly what he said it would the group opened up to 1.5

Back to the testing , So I started with 59gr of rl19 up to 61grs. in increments of .3 omitting the 59.6. the magic number is 60.2 overall grouping was 1.3 w/ 3 touching at about .77 Iam going to try 60,60.1 and 60.3 just to see what happens. besides the fact I just love too shoot as much as I fish.
As far as the win 760 most of what i shoot was any where from 1.3 with 4 rounds touching at .668 up to a 3inch spread group. What data do you use? I use the hornady data for the woodleighs.
So far a hunting rifle thats not bad. I will continue to work with it for the fun of shooting.
Any assitance is greatly appreciated.

I've given up on ww760, it is just too fast burning. It runs into serious pressure before getting close to the velocity potential of the 300 WSM cartridge. 3 powders that have worked well are, R 19, H 4831SC, and AA XMR 4350.

I gave up on winchester brass, went to Norma. The Norma brass holds pressure better without loosening primer pockets. It's more consistant as well. I hate getting a bag of fifty cases from WW and haveing to shitcan 2 cases because of cracked necks.

The best group so far is .484 3 shots with the 165 Horn. interbond. I won't post the load, it's 2.0 grains over what Hornady said was max for H 4831SC.


I shot another group 2 days later that came in at .560.




I only use standard Winchester primers, unless a mag is called for in a particular load. The short-fat powder column of mid burn rate powder doesn't require that hot a primer to get it going.

Just tested some of the new 180 interbonds, a preliminary work-up yielded a .950 3 shot group. This was with R-19, again above what Hornady claimed should be max.

Now to head off the paraNOIDS, I do the overloads carefully while watching the velocity with my Pact chrono, a micrometer handy to measure pressure rings and carefull notice of primer pocket tightness when reloading that brass. All the measurements and velocity was in the safe zone, the pockets were the same tightness as new brass.