I can't help much, except to provide you with some info courtesy of the SCSW 5th Ed. Your 610-2 "10mm Classic" is actually a 4" bbl. (introduced in 2001, Product Code 103571) with the unfluted cylinder that was standard production (not a special distributor run). The 1/8" barrel length difference (3-7/8" vs 4") is common with S&W revolvers. There were 300 Model 610-2s made with a 3" bbl. and unfluted cylinder for Lew Horton in 1998 (PC 148120), but that's the only special run that I've found. I don't own a 610 so I can't speak to shooting .40 ammo, but I do use TK Custom, Speed Beez, and RIMZ EZ moonclips for my .45 ACP and .357 Magnum revolvers. The RIMZ are plastic and very easy to load/unload, and I know that they make them for your 610. I've seen asking prices for the Lew Horton 610s in the $3500 range, but standard production 610-2s only around $900. Enjoy!