Hello ! Im having a xp built in 300 wsm , went with 18" bartlin barrel , 5R 1-10 twist , holland brake, PTG bolt, my question is what powder do you guys think would be best , Im going to shoot 175 gr berger VLD Hunting, 178 gr hornady ELD-X bullets , and what kind of velocity should I get ? Thanks Jimmy Burton

Running H -4350 and 168 Amax's, my 14" .300 WSM averaged right at 2500.

2550-2600 fps...Guessing

Ran RL15 + 165 nos but in mine, 15" barrel excellent accuracy and velocity in the 2775 range
Nmhunter

I have a virtual ballistic twin of the 300WSM in my T/C Encore 30-338 Win Mag.

That bbl in the 30-338WM will push 175 Berger VLD's at 2700+ FPS (loads with new brass will do 2850 FPS using 68.0 grains IMR-4350, but case life is short with some cases showing eminent case head separation within about three firings. Primer pockets are still tight). However, in the interest of brass life, I now load 66.0 gr of IMR4350 and this load runs right at 2725 FPS.

My barrel is 16.5" long, and is a tight bore (.299/.307) which likely adds some velocity due to more pressure.

Looking at load data from various reloading manuals, I'd say the 300 WSM should be a virtual ballistic twin of my 30-338WM.

I would expect a 300 WSM to do something on the order of:

150's @ 2950 FPS
165's @ 2850 FPS
175/180's @ 2700-2750 FPS.

That 18" bbl will help retain some velocity as well. You could look at the Berger manual, and deduct what they say in their pages for velocity loss/increase per inch of barrel length. It's pretty close.

Also, a reduction of about 10% from rifle barrel length to a shorter barrel (ie 15"-18") is pretty common.

I thought the WSM case had less capacity than the WM case..I was wrong again
Looks like my guesstimate is low.
Good to hear from actual users

quote:

Originally posted by Ernie:
I thought the WSM case had less capacity than the WM case..I was wrong again
Looks like my guesstimate is low.
Good to hear from actual users

The 300WSM does have a less case capacity than the 300WM case, but compared to the 30-338WM case (338WM or 7RM parent case), it's only slightly less.

Since my 30-338WM is in the Encore platform, and the OP is planning on an XP build, it should be a virtual ballistic twin based on my reviews of load data in the manuals I have that list both cartridges (or in some cases, the 308NM version).

I almost did a 300WSM build on my own XP.

The 30-338 is a nice round. I have just started to play with it in a custom model 70 rifle. Of course at 26" a guy would have more fps, but the thing I have noticed is the accuracy is really good. I will have more load data I will share as spring hits here in Wisconsin. It will be interesting to compare velocities.

I have a 300 WSM Striker with a 16.75" McGowen barrel. A 165 gr, RP Ptd SPCL does 2996 fps over 68.0 gr of AA-4350 fired by an F-215 primer. Federal 165 gr. Fusion ammo generates 2853 fps. I have had my best velocities with AA-4350 in this barrel.

Thanks guys , I just happen to have a 8 lb jug of IMR-4350 , so looks like I'm in business! !!!!