I can't speak to oversized factory chambers; but do know at least 2 people off the top of my head,who have punched Rem 700 rifles out to 7mm Mashburn.
One rifle has only been shot a little so far,but exhibits no brass issues and shoots accurately.
The other is owned by a guy who has had the rifle all over the place on BG hunting trips, including to Mexico last year for a record book Desert Sheep. So I guess it's working out pretty well.
He has not complained about any issues that I know of.
I'd be at least the third:)
mine is a 24 inch pipe model and it shoots 150 grain ballistic tips to 3220 with a bit of room to spare, 120 grain x to 3500, 140 grain x to 3330, and 150 swift scirroco to 3180.
personally I was expecting more snap than that but it is pretty consistant and is really more power than I really need.
79 you may find this interesting.
" The big cases like the Mashburn show more gain over the smaller cases like the S&H, Weatherby,and Remington with heavy bullets than with light bullets..." "Guns, Loads and Hunting Tips"; Bob Hagel.
This will show up if you load extensively for progressively larger cases in the same caliber and I have seen this with the 300 WM vs the 300 Weatherby; the 338 vs the 340; the 375 H&H vs the 375 AI;the 7x57 vs the 280,and on it goes. Gunscribes who have seen the same thing and written about it include not only Hagel, but Bob Chatfield -Taylor as well....which goes to show, it isn't recent "news".
And...." After developing loads to maximum trouble free hunting pressures for 7mm cartridges ranging in capacity from the little 7/08...to the big 7mm-300 Weatherby wildcat, it seems the Mashburn Super Magnum has about the optimum powder capacity for the .284-inch bore diameter with available powders......The Mashburn offers only about 100 fps over the 7mm Remington and 7mm Weatherby cases,but whatever advantage there is lies with the slightly larger case." Guns, Loads, and Hunting Tips; Bob Hagel.
