300 WSM load workup

I just worked up a load for the Speer 190 gn Impact using 66.5 gns of IMR4530 with a WLR primer. It is my go to powder for my 338wm so I had a couple of pounds on hand. It is listed in the load data that came with the Speer bullets so I thought Iwould give it a try. I was surprised how well it worked with that heavy of a bullet. Sub MOA at 3012 fps.
My previous favorite powder for the WSM has been RL17 which is not available.
 
N555 has been incredible in my 300 wsm improved (Sherman mega). Not a whole lot of useable capacity difference, couple grains at most, since it's basically a long necked 300wsm with the little shoulder change to 40 and taper blown out. I just started fire forming and have has single digit es every outing and accuracy is crazy. Not the fastest at all but the consistency and accuracy is great. Running a 210 rdf with 210m primer at 2715 fps pretty mildly for fire forming. This is a 28" barrel though. 5 shots this morning without having a super steady setup and variable wind put 4 in 5" horizontal at 1066 yards es of 6.5 fps. Took the first shot to remember I haven't reset the zero stop on my scope which is why it was a 4 shot group. I'm excited to get these formed and see if there is more speed on the table to be had but if not and the accuracy is there it doesn't matter.
 
I've had three 300wsm. Most finicky was my CA Ridgeline. I found after more test rounds than my wallet wants to acknowledge that across the board they all performed best in the 170-190g class and typically with a 59-61g charge of H4350 seated around .010" off to start. That same Ridgeline shoots awful fine groups now with 185g VLDH over 61.2g H4350 @.05" off rifling and REM 9 1/2M. Good luck…and here's some pages from the Berger book incase you wanted to see some published data
 

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+1 on H4831sc. Been reloading for a 300WSM with various bullets since 2003. Always gave very good accuracy and good velocity.
 
I use rl26 with 215 bergers in my 300wsm--- I might stop though and save my last 8 pound jug. I'm pretty sure I can sell it for about $1500 in a year from now 😉
Im sure it's a killer combo but unfortunately I have less than 3 pounds left. With the gunbroker prices of RL26 today, I'd rather buy a MacBros receiver and use H1000🤣
 
Of the 4 300 WSM hunting rifles I'm loading for- 2 like Superformance and 2 like RL26. Early on I worked up loads with many of the powders mentioned and settled on these 2 for my rifles based on good accuracy (at least .75 MOA) and desired velocity with 165-190 gr bullets. Super can be more finicky but once dialed gives good/consistent overall performance - and good news is that it seems to be widely available. Really like RL26 but once my limited stock is gone I'll have to look for alternatives and its most likely all of them will be running Super. JME - good luck with your load development.
 
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For guys running Staball 6.5, how is case fill? My 300 wsm+p will be done shortly and I'm wanting something that won't overfill the case before pressure on a standard wsm.
 
For guys running Staball 6.5, how is case fill? My 300 wsm+p will be done shortly and I'm wanting something that won't overfill the case before pressure on a standard wsm.
I'm also running the 6.5 staball with 180gr. Nosler Partitions in my 300wsm t3x. I LOVE that setup and the case isn't even loaded hot for the accuracy I'm getting.
 
Running the Berger 205 EH's in my Nosler model 48 Liberty rifle. 24" barrel. New ADG brass. 210 match primer with Reloder 23. Very accurate at 2870 fps. I did try 210's with 26, and those are definitely a possibility. I'll go back to that load and test it more after I get through virgin brass. Barrel is still just under 100 rounds too. So lots of potential hopefully.........
 
For guys running Staball 6.5, how is case fill? My 300 wsm+p will be done shortly and I'm wanting something that won't overfill the case before pressure on a standard wsm.
with heavier bullets you will pressure out with 65Stabil before you run out of space! Im running 208's and ive had to back down to avoid over pressure and still have room for a few more grains. If thats what your looking for
James
 
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