If a revolver cyl is cut for full moon clips, do you have to use them or will it function fine without them?

If there is a lip on the outer edge of the cylinder you can use loose ammo.
What model is it? 10mm, 40, 9, and 45 have to use clips.

S&W 640 pro-series, 2 1/8" barrel, bantam grips, stainless, night sights, in 357 mag

Thanks, it does have the lipped rim. The only gun I have like that is my bearcat.

Gun looks like this except 357 instead of 327:

http://www.fortune3.com/Bigskyguns/Pro_Series-S_W_Model_632_Pro_Series.html