Count me in as another Mashburn user. Mine is basically a duplicate of Farese's gun, built by same builder using pretty much the same parts with the exception of the barrel.Mine has a Bartlien and his a Krieger, both in 9 twist. I had another one but eventually rebarreled it to 7mm Rem mag. Having 2 wildcat chambers cut from different reamers is something to avoid, trust me on that!
Mine is like Beretz's gun in that it has a long throat, the reamer was ground specifically for 175 Noslers and like his, it shoots very well with them but not so good with lighter/shorter bullets. I've had another reamer made to the same body spec's but with a shorter throat and it will be used this year on a new barrel to be installed on the gun.
This rifle has taught me a lot about cases and how they match up with sizing dies. My original Redding sizer was apparently made to a smaller case dimension in several critical areas and it over worked the brass a lot. This caused excess pressure even with moderate loads and I trashed many cases before finally having a custom Whidden sizer made to match my chamber. Since then life has been much better and I'm finally getting the speeds I'd hoped for, all with good case life. If I were to give any prospective Mashburn owner a bit of advice it'd be to have a custom die made from your brass, it's just a crap shoot to buy a standard die and expect it to fit your chamber correctly.
From talking to various folks, it's reasonable to expect 50-75fps more velocity than a Rem mag will offer from same barrel lengths. Sometimes you get a "fast" barrel and can see more than that, but in general I've found that to be close. My 25" Rem mag pretty much equals my 24" Mashburn, so if case forming, then fire forming, then reaming donuts and buying custom dies doesn't appeal to you, just put a 25" or 26" barrel on a Rem mag and be happy! No elk, deer or moose will ever know the difference. But if you're a gun nut and like a bit of nostalgia to go along with having a very well balanced cartridge, the Mashburn is definitely worth having.

Edit. Mine has a Legend stock with Edge shell/fill and it is a bit finicky as to loads. I also have a 300 Win mag with same stock and it exhibits the same tendencies.

Last edited by John55; 04/23/20. Reason: added info.