I didn't bring up the Mashburn...you did.
The thread was about the 280AI. I offered comments about why I never saw much use for it, for me. Not enough gain over a 280 to bother with and a 7 RM did the same things easier.
I know all about long throating the 7 Rem Mag for 160's and getting 3100-3150 with a 160,since i was doing that in the 1970's-80's and have had several rifles set up that way and probably have shot a few thousand rounds through them.And killed a pile of game with them. I know the benefits and the downsides having BTDT,
Even given that, you are pushing the cartridge....hard...to places it was not meant to be.
It also makes the cartridge a bit easier to load for and work with.But I also know the neck is short,and if throated to the 160, other bullets have a long jump to the lands. You have fewer options seating bullets.This comes as a result of the makers insistence that it fit a 30/06 length box...meantime tens of thousands are running around with H&H length actions like Rem 700's and post 64 M70's with blocked boxes (all those unreasonably heavy magnum actions that no one can lug up mountains.)
The 7 Rem mag case could use (a) a longer neck and (b) a bit more capacity. The Mashburn fills both those requirements without going over board in capacity. Bullet to land relationship is better,and case capacity is increased enough to nudge velocities into the STW range..with good case life. The Mashburn is a better design,Better mousetrap.
That said, if one wanted to,the Mashburn will also fit a 30/06 length box if you like to seat bullets deeper,just like a 300 Win Mag.If you are constrained by magazine length (like a Montana in 280AI), then you have no option but to seat deep.The reason a Rem 700 is a better "tool" for a 280/280AI.Throat accordingly to your bullet of choice.
Increasing case size to an STW does not buy you "more"...the longer case in a H&H box requires deep bullet seating.Velocities will be very much the same as a Mashburn. You may see a slight gain with the STW but it won't be much and will mostly show only with 175 gr bullets,and with a 26" or longer barrel Guys like Mashburn and Hagel worked this stuff out decades ago.I've seen it myself working with both. Maybe you missed this....Powders change but relationships remain the same.You can read and learn only so much.The rest takes shooting.
The Weatherby needs free bore. If you want that have at it.
Big Stick has lectured endlessly about this relationship between mag box constraints,throat/leade dimensions,seating arrangements with various bullets,etc. Clearly he gets it and people should listen. It isn't always about capacity....some cartridges/rifles are (to paraphrase him) a goat puck out of the box.
It isn't just about speed and capacity...it's about what's "optimum".
Last edited by BobinNH; 05/24/15.
