7mm-300Win Mag.

dthunter

dthunter

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What do you gunnutz think of that combo? I know it has been tried, but what are the results? Any idea of the velocities with 168 or 180gr. Berger Vlds? What do you guys think the barrel life ecpectantcy would be like? 1500-2000 rounds? What length of barrel would you go with 26-27? I would go with a very heavy taper. Maybe 1" at the muzzle. Would you guys go with a 1 in 9" twist? Lets hear what you guys think. I look forward to hear from you. Have fun, and straight shoot'in!
 
I suspect the 7mm 180 grain velocity would be about the same as the .308 180 grain velocity in the parent cartridge, all things being equal.
What do you mean "barrel life"?
 
Other than very small differences in neck dimensions, the cartridge already exists as the 7mm Remington Magnum. 180's can be shot north of 2900 fps in the 7mm RM

Give some thought to the Matrix 190s!
 
7RM, 180gr Berger VLD, healthy dose of Retumbo, Win and Rem brass, Fed 215M primer, 26" Shilen CM match barrel prefit for a Savage.

Velocity just under 3100fps and in the 2's and 3's at 200yds. Never shot it further cause someone wanted it way more then me.

I wouldn't bother with that wildcat vs the 7RM. The increase in case volume is peanuts and the hassle to set up is huge.

The 7RM has more then enough case capacity to burn out your barrel under 1000rds.

I sincerely doubt you will get very good accuracy north of 1000rds. Likely peak accuracy is in the 500 to 800rds range.

Jerry
 
Seems like a bleak idea guys! thats probably why I havent heard much about it. Mystic Precision, do you really think 7mm Mag barrels typically last only 1000 rounds!? Wow! I had no idea that it was such a barrel burner! Bummer!

Within the same class of cartridges, what do you think has the best barrel life? I like to shoot a fair bit, but i would like to get at least 1500-2000rounds out of a barrel. I guess theres no such thing as a magnum rifle thats easy on barrels LOL!

Thanks guy for your replies! Have fun and straight shoot'in!
 
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Your definition of "accuracy" will determine your barrel life. If you compete seriously your barrel will be "gone" when you can't group 1/2MOA at 600+ and most likely that will happen before 1k rounds with a lot of these cartridges. If you want to shoot the 180's and get "decent" barrel life, I would look at the straight .284Win. You won't get the velocity of the RM or short mag, but it will last longer..
 
3100 fps in 7RM with 180's? Wow! Didn't know you could do that.. I would definately be approaching that with caution.

I think the manuals top out at something like 3050 fps for only 160 gr bullets.

I will take your word for it though Jerry! Did you have to push it that hard in that barrel in order to get that kind of accuracy?
 
overboreindex2011.png


This chart shows a continnum of overbore cartridges. You can see that the 7mmRem Mag has one of the highest overbore indeces going, but this index is a guideline. Different loads/powders and excessive barrel heat all greatly influence life, and thus accuracy

The 6.5-284 can go in as few as 600 rounds or as many as 1200. I would never take one to a match with more than 500 down the pipe. The 30 BR basically never wears out.

308 Win is good for as few as 3-4000 ultra accurate rounds, or as many as 10,000. 6BR is good for about 2500 +/-
 
I was happy to get 3000 fps with 175 grain bullets out of a moly coated barrel, with moly coated bullets. I would be surprised to find any velocity above this was a real improvement.
Just my 2 cents worth
 
Hey Obtunded, that's some great info. Thanks for that post.

I've been toying with the idea of building a 7mm rig suitable for 1000 yds however I'd also like to be able to push it out to 1200-1500 yds for fun every now and then. Since the 7mm RM is so Overbore, what would you guys say about a .284 out of a 30 some inch barrel?

(apologies for possible hi-jack)
 
I shoot one with a 30" tube, 62.8 grains of 22 and it is movin at 2909 average in ten rounds. This with 180 grain Bergers. At 1319 it still swings the gong like a SOB.I agree a little over bore but you can't beat the BC. Even after, I would still throw another pipe on it and burn it again.
 
I have a pre 64 model 70 in 7mm Yukon. With a 160 grn accubond I'm getting 3250 fps! It is a blown out 300 win mag case so it has a quite a bit more volume. Shoots like a dream! I have gotten .250" groups at 100 yards. Love that rifle!
 
Obtunded said:
Other than very small differences in neck dimensions, the cartridge already exists as the 7mm Remington Magnum. 180's can be shot north of 2900 fps in the 7mm RM

Give some thought to the Matrix 190s!
Click to expand...

Not exactly true. A case based on the 300WM would be longer and give you added capacity, somewhere in the neighborhood of 8-9%. Would this give you a substantial performance gain over the 7mmRM? Not really.
 
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