Hi Rick,
The 4" S&W M629 with full power loads is a handfull with sharp recoil. I have owned S&W M629's in 4", 5", 6", 6.5", and 8 3/8" barrels. For ease of carry and general shooting, I like the 5" Classic with open sights. For serious work (hunting deer, wild hogs, and turkey) I prefer the 6.5" Classic gun with 2X Leupold scope. At 66, I can still shoot open sights on targets but have to use a scope in the field to see both target and sights (cross hairs) sharp at same time. The 5 inch Classic with full underlug does tame the recoil noticeably better than original 4" 629 without full underlug. The 6.5" with full underlug tames recoil even better than the 5". I had problems with 8 3/8" barrels shooting free hand but can handle the 6.5" well. From a solid rest or if you can hold them, the 6.5" and 8 3/8" guns with scopes are amazingly accurate.
Good shooting and be safe.
LB (ex 1911 Forum junkie)