Butcher, I've had one for a few years. Super ballistics, but with performance comes a price: 1. Throat erosion, 2. Muzzle blast, 3. Expense. The recoil isn't bad - mine's mainly a target gun & is comfortable enough to shoot conventional 1K from a sling.
Lerch's comments on J4 jackets are correct. When I built mine the 7mmRUM was a wildcat. I called several bullet makers (Walt Berger, Jimmie Knox, & Bob Cauterucio) and had some long & educational discussions on design, construction, & RPMs. Walt told me himself that it was iffy if the 180 would hold up at the RPMs we were looking at. Obermeyer Barrels tried it & blew up bullets - thin jackets. It's right on the ragged edge, & I'd avoid it on game if possible. It MIGHT work for you, but there's liable to be better options.
JLK & Cauterucio use Sierra-thickness jackets on their projectiles. I've mainly shot Cauterucio 176s & 156s. Both perform very well out to 1K. You might also look at Sierra's .284" 175gr MK. Pretty solid bullet. The most consistent powder I've tried was 5010 pulldown. At @ $4.00 per pound it's a refreshing change from the other expenses. Retumbo shot OK. None of the other DOZEN or so I tried were anything to write home about.
Just my $.02, take it or leave it! /ubbthreads/images/graemlins/wink.gif