The Mashburn is a very nice round, & I'm not attempting to belittle it in the least, but I've gotten those same velocities out of a couple of long throated (to seat 160 Partitions to the base of the neck) 7mm Rem Mags w/o all the hassle of the fire formed case.
MM
I agree with you just one thing nice about the mashburn is you don't have to lean on it to get it there. I built mine to have something different. I knew it wasn't going to accomplish something that hasn't already been done.
That's it in a nutshell.
Yes I have had a few long throated 7 rem mags, set up in a 3.6" box and throated to take the 160 Partition seated with base of bullet even with base of neck. velocities approach but don't equal, the Mashburn.I did it because Hagel and Wooters said it was a good way to go.
And I always had the feeling that I had absolutely maxed out the 7Rem Mag.OTOH the additional capacity of the Mashburn gets 3150-3200 with a 160 rather easily. Max out a Mashburn, you are at 3250. I have yet to see primer pockets opened operating the Mashburn at those velocities.
The other problem with the long throated 7 RM, is that if you throat to the heavier bullets to optimize it in a long magazine, shorter, lighter bullets will have "jump" to the lands. The neck is too short. And you still will not have the capacity of the MashburnThe longer neck of the Mashburn helps alleviate some of this.
Does this matter? To some it does,if they like everything "just so". Holding cartridge OAL to 30/06 levels the 7 RM may be ether because that's how it was developed and designed. But in a 3.6" box, the Mashburn is the better tool.
Thing is, comparing the cartridges is a hollow exercise. The Mashburn came first;it was designed to be (what Doc Bill said this afternoon on the phone) a "cheater" 300 magnum....give a 175 gr bullet over 3000 fps. Without the bounce of a 30 caliber magnum.There really was nothing else that did this.
At the time,the 7mm Weatherby was proprietary, had a 12 twist, and shot 139 gr bullets.It would not stabilize 160 gr bullets...at least then. The Remington came later,and was designed to fit a 30/06 length action and approximate Mashburn velocities, not the other way around.
Case forming is something I used to worry about; for years it kept me from building a Mashburn. I got over it. I can start after breakfast,and by mid afternoon will have turned 50-100 300 Win Mag cases into spanky new Mashburn cases, sealed in plastic bags,and ready to load to hunt about any soft skinned game, anywhere.That includes a break for lunch and driving time to the range.
For me and friends who like the cartridge due to its easy going nature and delivered high velocities,this is no big deal.
And after I fire them the first time, it's like loading any other cartridge.
It may turn out I don't even have to do that if i don't want to.....but that's another story.