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300 WM vs. 300 WSM

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  #8  
Unread 07-03-2009, 09:00 AM
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Re: 300 WM vs. 300 WSM

Tank,

I am a handloader, so thank you for the information. If you have any more relative to what you are using to load your rounds, please share. Any information is appreciated.
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  #9  
Unread 07-03-2009, 11:30 AM
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Location: South of Canada and North of Wyoming
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Re: 300 WM vs. 300 WSM

head2h2o,

Traditionally the WM has had a slight edge over the WSM, especially in the heavier bullets. However, with the introduction of RL17, the 300 WSM "may" now have an edge over the 300 WM. I recently shot 180 E-Tips @ 3193 out of my Sako 24 3/8" barrel with 67.5 gr of RL17 and...... I also shot 210 Bergers @ 2935. These velocites exceed published data for the 300 WM by about 100 fps give or take 50 fps. Having said that, not everyone seems to be getting extraordinary results with RL17, but many do. Also, RL17 may increase WM performance, but probably not to the same degree because it was actually designed for shorter, fatter cases.

If I was to build a 300 WSM, I would use a standard size action and the liberal freebore I currently have in my Sako to allow seating depths that seat the bullet to the lands without encroaching on case capacity. When I seat a 210 Berger to the lands in my Sako, the bearing surface of the bullet only catches about 2/3rds of the neck. If I tried seating a 190 Berger to the lands, it might be falling out of the neck. So in doing your build, whatever you decide, make sure you use an action and chamber the throat for the bullet range you want. On twist... any custom .30 cal barrel I ever order will have a minimum of a 9 twist (and maybe 8) to accomodate the longer high BC custom and wildcat bullets.

Bottom line... If the build is properly designed, and with the right powder and primers, a 300 WSM will come very close to the WM if not actually exceed it, even with the heavier bullets. Assuming the performance of the cartrides is roughly the same, the advantages of the WSM will be longer barrel life and a shorter action compared to the WM. The advantage for the WM is better brass. But you can get Norma brass for the WSM which is great brass if you dont push the pressure limits.

My 30 cal preference... If I were to do a build right now it would be a 300 Dakota which has better performance than the WM or WSM. It also has a fat, somewhat short (not long) case which might be favorable to RL17 performance. it could theorhetically come close to the 300 RUM in performance with significantly less powder. Brass for the 300 Dakota is made by either Hornady or Norma and is not cheap.

Finally, if you really want to shoot to the "longest" ranges and rifle size/weight does not matter then get a 300 RUM or LARGER, fit it with a 9 or 8 twist 30" barrel Sendero contour and you will be killing elk @ 1500 yds or more, especially if some good custom high bc bullets come out. With that size of rifle, recoil should be very tolerable.

Hope this helps and have fun with your project,

Regards,

-MR

Last edited by MontanaRifleman; 07-03-2009 at 04:48 PM.
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  #10  
Unread 07-03-2009, 02:05 PM
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Re: 300 WM vs. 300 WSM

The 300 WSM competes very well with the WM due to its higher percentage of useable case capacity. When you look at the cartridge designs side by side you will see it is actually the WM that runs into case incringment problems first. I think too much is being made of the short fat case vs the traditional case.

The WSM SAMMI OAL is 2.86 and the case length is 2.1". That means .76 inches of bullet can be set outside of the case and no capacity is lost. The wm by comparison has an OAL of 3.3402 and the case length is 2.6201. That means only .72 inches of bullet can be set out of the case before case capacity is lost.

When you look at the dimesion beyond the neck and to the case itself the WSM actually has a bigger advantage. the distance from max OAL to where the shoulder starts on the WSM is 1.058 inches vs only .984 for the WM.

Due to its longer case the WM case gives up slightly less capacity than the WSM does when bullets encroach into the case below the shoulder. With long bullets this can negate the WSM advantage in useable capacity.

If you pick the right action, magazine, and throat the barrel to allow the bullets to set out of the case the WSM will run right with the WM over a broad range of bulletweights and lengths because it is useable capacity that really matters. That being said if your action will allow you to do the same with the WM with its 10 grain case capacity advantage and it will be 75 to 100 fps faster.

My personal choice would be a WSM chambered rifle that could feed rounds 3.1 to 3.2 inches long to handle high BC 180s and 200s.
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  #11  
Unread 07-03-2009, 03:55 PM
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Re: 300 WM vs. 300 WSM

This load is near maximum in my 300 Win Mag bolt rifle: <1/2 moa out to +600 yd
Lilja 25.5" barrel
Lapua Brass
Federal GM210M
74 gr IMR 7828
210 Berger VLD
2970 fps MV
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  #12  
Unread 07-03-2009, 04:55 PM
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Re: 300 WM vs. 300 WSM

Quote:
Quote:
Originally Posted by phorwath View Post
This load is near maximum in my 300 Win Mag bolt rifle: <1/2 moa out to +600 yd
Lilja 25.5" barrel
Lapua Brass
Federal GM210M
74 gr IMR 7828
210 Berger VLD
2970 fps MV
Paul,

That's good velocity... Is that after gun juicing your barrel?
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  #13  
Unread 07-03-2009, 06:24 PM
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Join Date: Nov 2008
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Re: 300 WM vs. 300 WSM

Guys, thanks for all the information. I knew there was a reason I came to this site to ask this question.

Am I going to see any advantage to a barrel longer than 26" with either caliber. I have typically always stayed around that length but would certainly consider going longer if there would be a reasonable addition of velocity.

Also, can anyone tell me the pro and / or con of using a belted cartridge vs a not belted.
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  #14  
Unread 07-03-2009, 06:38 PM
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Join Date: May 2008
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Re: 300 WM vs. 300 WSM

Quote:
Quote:
Originally Posted by head2h2o View Post
Also, can anyone tell me the pro and / or con of using a belted cartridge vs a not belted.
"Belts" are unneccessary and I just dont like them I have also shot a 7RM for many years. Other than that, not not much of a difference except maybe some minor handloading issues with head spacing and FL sizing vs neck sizing.


-MR
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