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300 grain SMK velocities with .338 WinMag

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Unread 11-27-2002, 11:22 AM
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300 grain SMK velocities with .338 WinMag

Can anyone tell me what velocities I can expect with a 300 SMK out of a standard .338 WinMag? I have a remington SS-DM and these bullets will fit nicely in the magazine. My only alternative is to go to a .300 Weatherby. Not even a .340 Weatherby will fit the detachable mag. I know they are supposed to be the same case OAL, but when trying factory ammo in the mag, the .300's will fit while the the .340's won't. They're slightly longer right out of the box.
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Unread 11-27-2002, 02:03 PM
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Join Date: Dec 2001
Location: Canyon Ferry, MT
Posts: 324
Re: 300 grain SMK velocities with .338 WinMag

Here are some Quickload calculations,

With a 3.5" OAL, that 300gr Sierra is going to eat up a large amount of your case capacity, and still stick out an inch (assuming your rifle is throated to handle it). For the .338 Win, Q/L also lists a max PSI of 62.4K.

In a 26" barrel, Q/L predicts:
75gr RL-25 @ 2600 fps 62.1K Psi - casefull of 115.1%
76gr RL-25 @ OVER MAX PRESSURE - casefull of 116.7 %

RL-22 provides a nicely filled case and still reaches 2500+ fps in a 26" barrel.

68 grs RL-22 @ 2512 58.3K Psi - casefull 102.7% - - 32.4 % eff
69 grs RL-22 @ 2547 61.3K Psi - casefull 104.0% - - 32.9 % eff

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Unread 11-27-2002, 02:50 PM
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Join Date: Aug 2002
Posts: 166
Re: 300 grain SMK velocities with .338 WinMag

Thanks guys.

I'm getting nearly 3300 FPS with Nosler ballistic tips and about.6" groups. They blow up on the surface at anything under 200 yards.

I'm now shooting 200 ballistic tips at an average of 3077 with 75 grains of Vit N160 and am hovering around an inch - 5 shot groups. Most just under, some just over - like 1.06, 1.16.

I killed a couple of deer with 250 Sierra Game Kings last week and was blown away by their performance at short range ~175 yards. I only tried 3 shots and shot virtually one holers with hot loads. I didn't measure my groups, but in a couple, all bullets were touching. In the rest, they were definitely acceptable, and the smallest groups I've ever shot with this rifle.

I'm anxious to try the 300s now. Just for fun if nothing else. I'll have to check a ballistics program to see what they'll shoot like.

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Unread 11-28-2002, 12:37 AM
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Join Date: Jul 2001
Posts: 1,459
Re: 300 grain SMK velocities with .338 WinMag

Sheldon, with the shorter factory barrel and small case capacity of the 338 Win mag, I would guess around 2400 to 2500fps. Not the most exciting performance. Also, how much powder compression is there to fit the 300MK in the mag?

You may want to consider the 250gr MK/Lapua or the 225gr Ballistic tip/SST. For hunting inside 1000yds, I doubt you will see a difference on deer. This way you can get up to 2800 to 2900fps for a flatter trajectory and higher impact vel. Will fit in the mag and case no problem.

Good luck...

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Unread 11-30-2002, 02:55 PM
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Re: 300 grain SMK velocities with .338 WinMag

Sheldon: I know you have told me before, but what brand and model rifle is your .338 Win Mag. That is a pretty impressive report on the accuracy you got with the 250 grain Sierra Gamekings. Boy, would I love to have a .338 that will do that! Thanks again.
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Unread 11-30-2002, 10:47 PM
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Join Date: Aug 2002
Posts: 166
Re: 300 grain SMK velocities with .338 WinMag

Hi Jon.

It's a model 700 SS-DM that has been completely trued and blueprinted, pillar bedded, barrel hand lapped and custom muzzle brake installed. The groups shot were done so using a hart accuracy asset, heavy front rest and Protector bunny ear rear bag. I'm emabarrassed to say that the barrel is a factory tube. I don't have my records in front of me, but I believe the load is 75 grains of H4831.
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