Interesting chronography results found here: http://www.leverguns.com/articles/ballisticians.htm.

You'll see that there is a lot of variation from gun to gun, and that some of the 4" guns even shot as fast as the 6" guns with the same loads. Thus, I'd not concern myself with ballistics much. I'd choose based on ease of shooting versus portability. For me, the handier, more portable 4" gun would win out in a wilderness gun, or one that may be used for home protection. Either is fine for casual target shooting.

A number of years ago, I chronographed many of my handloads in .38 Spec., .357 Magnum, .44 Magnum, and .45 Colt. I clocked these in revolvers as near alike as possible, using a 4" and 6" barrel.

There were some surprises in the endeavor, as some of my loads, especially in .357 Magnum, actually clocked higher in the 4" than in the 6" barrel. I don't have the data in front of me, but remember that loads concocted with Hercules (then) 2400 gave me this variation.

But, as has been pointed out, don't get too hung up on bullet speed.

Bob Wright

I am right in there with Bob and Mike and I would take the 4" for woods packing. With that GP-100 you can shoot anything out there for the .357rd. Practice with the round you like and old Blackie better beware if he messes with you. Just remember to keep it on your hip out there in bear country.