7mm Rem Mag vs. 7mm-300?

aramarine6

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I've been shooting a 338 for some time now and I've been kicking around the idea of rebarreling to a 7mm mag. Running some rough ballistic numbers I can match the performance of my 338 RUM with a 180 Berger in a 7mm(minus energy) and with half the amount of recoil. With that being said, what is the benefit to going with a 7mm-300? Is there added case capacity or is it a brass availability/quality issue?
 

Broz

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9 grains of case capacity and I have seen up to 200 fps increase in velocity with 180's Plus you still have very good barrel life and dies are as easy as using a 300 win bushing die and a bushing change.


Jeff
 

jrsolocam

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9 grains of case capacity and I have seen up to 200 fps increase in velocity with 180's Plus you still have very good barrel life and dies are as easy as using a 300 win bushing die and a bushing change.


Jeff

Jeff beat me to it. My smith told me about 200 fps. And relatively easy to get to shoot well.

Jon
 

deadidarren

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I've been shooting a 338 for some time now and I've been kicking around the idea of rebarreling to a 7mm mag. Running some rough ballistic numbers I can match the performance of my 338 RUM with a 180 Berger in a 7mm(minus energy) and with half the amount of recoil. With that being said, what is the benefit to going with a 7mm-300? Is there added case capacity or is it a brass availability/quality issue?

here ya go knock yerself out after reading 51 pages i'm putting a 7-300 on

my sendero when the barrel is done should be about another 5 months .

http://www.longrangehunting.com/forums/f19/anyone-own-7mm-300-win-mag-51404/
 

Lefty7mmstw

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9 grains and 200 fps? That's pretty impressive.


your mv increase should be 1/4 your increase in volume at the same pressures.... ie a 4% volume increase will net you a 1% gain at equal pressure. It could happen on a 7rem to 7x300 conversion, but I'd think the pressures would be up a slight bit too...not likely dangerous, but I get 180 fps max.... The 7rem usually runs a bit milder than the big 7mm's too and that could play here.
 

Methow Packer

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What do you think the barrel twist would be for 7MM/300 shooting 180VLD ? Are we thinking similar to any 7mm barrel for these bullets say 8 or 9" ?
 

Broz

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What do you think the barrel twist would be for 7MM/300 shooting 180VLD ? Are we thinking similar to any 7mm barrel for these bullets say 8 or 9" ?

The 9 will do fine with 180's, but go with an 8 so you will be ready for the 195 Bergers when released. The 8 twist shoots 180's very well to.

Jeff
 

Broz

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your mv increase should be 1/4 your increase in volume at the same pressures.... ie a 4% volume increase will net you a 1% gain at equal pressure. It could happen on a 7rem to 7x300 conversion, but I'd think the pressures would be up a slight bit too...not likely dangerous, but I get 180 fps max.... The 7rem usually runs a bit milder than the big 7mm's too and that could play here.

Yep, and the reason I stated quote " I have seen up to 200 fps increase in velocity "
 

tbrice23

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Dec 12, 2012
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One Question guys

I have been comparing 4D reamer specs between 300wm and 7mm 300wm. Looks like the same chamber length with same shoulder angle. That makes the neck of the 7wm about .238" long about .030 shorter than the 300wm.
I feel the 300s neck is too short as it is.

Do you guys mind the extra short neck on the 7wm?
 

trueblue

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Feb 18, 2008
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IOWA
Yes I do. That is why I went with the 7 Rogue instead of just a necked down 300WM to 7mm.
 
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