It is built on a Ruger #1 Tropical that started off in 416 Rem. Yes you can bring it up to 600 Nitro power level quite easy. Because of its 10.5 lb weight, recoil is very spirited when you take the 900 gr. bullets up over 1900 fps. JD @ SSK strongly recomends Bell Mast brass. I agree with him. I have loaded several of the cases more than 8 times already with no signs of problems. The two bullets I use are the Woodleigh 900 gr. SP and the Beartooth 1040 gr. hard cast heat treat flat point. I fire-form with the lead bullet and use them for practice loads reduced to about 1500 fps. If you're thinking of one of these big guys, I can give you some advise from experience. JD @ SSK can be a little rough around the edges, but he knows what he's talking about so I would listen to what he tells you. There is a lot more involved to the 600 JDJ than there is to just the standard 577 Nitro like RECOIL, avalability of bullets, more involved reloading, etc. Most people think they want a 600 until they have to load for it and especially after they fire their first full-charge load. After having said all this, I love mine. The target effect, penetration, and power of this round is something to see. Firing this round from a bench at full power is breathtaking. I use a Caldwell Leadsled rest modified in the rear pocket with foam inserts to keep the stock from cracking. The Ruger stock is not very thick in the rist and you can crack it here if you're not carefull. I can also give you some experience with modifying the safety so the brass will clear the action. I also have done extensive, in talking to JD, probably much more than SSK has, reloading with several powders and power factors. I'm testing some new loads right now, or as soon as the weather allows. Let me know if you need info.
Joe
