Yes, it's a good deal. Not GREAT, but worth it assuming the gun checks out OK.
The longer-barrel SBHs are generally not as desireable as the shorter. And blue is less so than stainless. It's not uncommon (depending on what part of the country you're in) for blued long-tube SBHs to go for $300ish, sometimes a hair less.
BUT: the ammo is worth a good amount as stated, and you can handle the gun and do a checkout number first. This being a transaction with a relative, you might want to go to a range with him and shoot it. Ruger does sometimes put out a "bad monday gun" with everything just slightly squirrelly.
Finally, if this is a deal with a relative, if Ohio allows private-party transfers in your situation then you skip sales taxes, NICS check fees, etc...which may reduce the cost over, say, a used gun at a dealer.
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Do you know how to sandbag-test a gun properly?
If you don't have a sandbag available at the range, go to a grocery store and buy a 5lb paper bag of either flour or sugar. Put it on the table on it's side, horizontal. Lay a rag of some sort on it so that barrel flash doesn't singe it and you'll still be able to use it in the kitchen later
. You want the gun ONLY touching the bag, with the butt of the gun held up off the deck. The barrel of the gun just forward of the frame is what rests on the bag.
Take your time, line up sights dead center on a paper target at about 15yds range, fire six shots of the magnum ammo. Go slow, wear gloves if you want, this thing is going to kick some but not too bad. Then check your target. What you care about first is total group size, where it is is less important as long as it's not so far off in any direction that the adjustable sights can't correct. It's even better if you can get it very close in windage (horizontal direction) yet have the rear sight be as close to centered-looking as possible. If the sights need major shifting to get the windage right, the gun wasn't put together real well.
What else...
A lot of people like to take this type of gun you're looking at and use it as a starting point for a custom. It's possible to have a 45 barrel put on and have your existing cylinder re-cut to a very tight 45LC chamber with dead even bores. This set of mods isn't that expensive and you can get whatever barrel length and front sight you want. By cutting a very precise set of 45LC bores you get good accuracy and long brass life for reloading, and it's safer to run major grade 45LC+P pressure.
This gun will have the "squareback" trigger guard. Depending on how you hold it and your hand size it *might* beat your middle-finger knuckle up some. If so you can either run a non-traditional grip set (rubber or wood) that fills in the area behind the trigger guard - a good example of wood grips to do so that are only about $70 are the Badgers:
http://www.badgercustomgrips.com/ruger_pistol_grips.php
If you have smaller-to-medium hands and the SBH grip feels too big, you might consider swapping the whole grip frame to either a Bisley setup (costs around $250 and the total work involved is high) or a Bird's Head compatible with your current hammer and trigger and available in brass for easy hand-fitting:
http://www.brownells.com/aspx/NS/st...p=9941&title=RUGER~+SA+BIRDS+HEAD+GRIP+FRAMES
While on the small side, some have reported quite decent recoil handling with these as long as you stay away from the absolute gnarliest 44Mag fodder. This gun with this grip, a barrel chopped to 5" or so and a custom front sight would be a way cool piece
.