Halfbreed -
Thought I'd chime in on this one...
Bought a used, but little fired 4" 629-4 about 3 months ago, & proceeded to work up a suitable load. Try as I might, I could not get any load combination to group for beans.
Finally, it came to me that this gun just might not like 240 grain XTPs, & that maybe hard cast would be the answer.
This led me to measure the cylinder throats w/ my dial caliper (for proper bullet sizing), & I kept coming up w/ .426" - which seemed a bit tight. At this point I started eyeballing the forcing cone (big burr, & roughly finished), & the lockup, which was.... "poor", on four chambers. Did I mention that the barrel was tightened a couple of degrees past top dead center, as well? Hmmm.
Contacted our friends at S&W "Repair Dept.", & their suggestion was to run a box of factory ammo through it, & to let them know if I was still having problems. Must be sub-standard reloads - right?. Duh.
Ran a full box of WW 240JSP through it w/ totally dismal (no better - maybe worse) results.
Off she went to S&W accompanied w/ a diplomatically worded (no - really), documented list of my observations. I also requested that they provide me w/ the cylinder throat size measurements.
Couple of weeks later, she shows up w/ super tight cylinder lockup (replaced the hand), a sticky trigger return, a rough DA pull, a new rear sight blade (

), a repaired barrel (looks the same to me...), no mention of the cylinder throat (they told me "not to worry about it") measurement, and last but not least, "inspected / tested, & passed" to their "standards".
A trip to the range today, confirmed my suspicions that the grouping was still....piss poor. Minimal improvement, if any.
Interestingly, w/ 2 different loads (2 full cylinders each) & same point of aim (off bags - at 20 yards), she seems to be printing different groups for each chamber. This is most clearly seen on the cardboard backing that was under the 2 targets.
I'll post links to a few "group pics" for your viewing pleasure. ;=]
So I guess, as w/ your 629, mine will be going back for a second visit home.
Hell..., maybe it's just ME, huh? Comments & suggestions are welcomed from all.
http://www.imagestation.com/album/pictures.html?id=2131969283&idx=17http://www.imagestation.com/album/pictures.html?id=2131969283&idx=16http://www.imagestation.com/album/pictures.html?id=2131969283&idx=15