I mostly shoot the 38 spl's through it but have done 357 magnums. I just use a high grip, the Hogue's really seem to do their job. I dry fired mine a couple thousand times for The Bride, which really helped, however we do have a thread going contrary to that.
I'd start with a box of 38 spl and decide from there. I was suprised by a couple of things. First 5 were stouter in 357. Second five, not as big of a deal and went ahead and rapid fired those, no problem. Not sure I would want to do that all afternoon.
More accurate than anticipated. Should say the first 357's through it had some other folks at the range looking over to see what the heck was going on over there. Can't imagine shooting that inside a house without hearing protection - Yikes!
Post your results, we like ours and Congratulations on the find. I bought the only one I have seen.