I have an identical 4"
I have the 4" as well which I load Barnes XPB 275g bullets. The hottest loads by far that I shot are the Corbon 440g Hard Cast Lead. Those things were the first ones I shot out of it and it scared me nearly to death. I was actually (a little bit) afraid to shoot it!
Then, I shot other ammo and found all the other ammo to be not too bad at all.
Hold on tight with both hands (both hands on the grips and no fingers ahead of, or around, the front of the cylinder as people have severely injured themselves by the gases which escape at the sides where the cylinder meets the forcing cone).
I got to the point where I'm pulling 1.5" groups (off the bench) at 50 yards. That's not bad, considering I'm using open sights. I changed the original S&W rear sight to a Millett rear target sight. PM me if you need to know what height back blade you might need if you should change over to Millett. I ordered one sight and the other two heights in blades and experimented and found the one that keeps the sight low, but is still high enough to have some adjustment at 50 yards.
You will want to carefully remove the three side plate screws, clean with alcohol and apply blue locktite to all three screws and carefully tighten with the proper-size screwdriver blade (don't mix up the screws!). I also used the blue Locktite for the Millett sight screw and found the other day that the cylinder thumb release screw was loose (which I never put locktite on), so I cleaned it up with alcohol and put a drop on that screw and tightened as well.
They tell you in the manual and at technical support not to use threadlocker on the compensator (black allen) screw. I didn't at first and kept it tight, however while shooting, the compensator became loose, which I noticed while cleaning the gun. I called S&W because the black screw was worn from the harsh vibration of the compensator and would not tighten the compensator any more - there was some wiggle in the compensator with the screw as tight as could be, without breaking it. Upon further investigation, I could see wear marks in the screw from the harsh recoil and subsequent vibration of the compensator into the screw. When I got the new screw, I cleaned everything up with alcohol to degrease, and applied some blue (maximum strength) Locktite on that as well, and it hasn't been a problem since.
The Hogue grip from the factory is perfect. I tried a Pachmayr for the heck of it and it was so loose and sloppy, I didn't even shoot with it and sent it right back to MidwayUSA without any hassles.
If you've ever shot large magnums (41, 44) then this gun shouldn't be too much for you. Hold tight with both hands and be careful not to let it come back and hit you in the forehead. I find with the 4" there is a lot of muzzle rise during recoil.
If you reload, you can work up some accurate loads (which are cheaper than factory-loaded ammo by 50% or more).
I find that when the bullet seats into the case -- even with a heavy taper in the case mouth (expanding almost to the point of splitting the top edge of the case) there is a tendency for some cases to wrinkle a bit on one side, or crush just a bit. I have found to prevent this from happening, I set my bullet squarely into the expanded case neck, raise the ram on the press to seat the bullet about halfway, lowering the ram on the press, rotating the case in the shell holder about 180 degrees and then completely finishing seating the bullet. Incidentally, I seat all my primers for everything I load in this manner -- partial seat of the primer, turn case approximately 180 degrees in the shell holder, then finish seating the primer. In no time, I got used to doing it this way and it's now habit and only takes a second or two longer, but ensures that the primers always get seated squarely in the primer pockets.
Because of the extremely heavy recoil, I make sure I crimp HEAVY into the cannelure so there won't be any jump of the other bullets out of their respective cases which are in the cylinder upon firing. I trim my cases after every resizing and use a dedicated RCBS roll crimp seater (RCBS #23838) and do that as my last step on all cartridges after seating all the bullets (in my tray of 50). That way, the crimp process is not connected to the seating process and it ensures I get a perfect HEAVY crimp into each cannelure every time.
Good luck!