your gun was made by uberti. your finish looks like their entry level model. nm means new model. i am not sure about all the differences between the nm and the old model but the old model had a screw to remove the pin in order to remove the cylinder. the nm just has a pin to pull to remove the cylinder. as for quality, i have 3 different models of the blued, case hardened uberti 45's. all are excellent with great fit and finish and very accurate even with the notch sights. i love mine.
Waltzes with woofs