220,
I like going to national forests close to home, here in Colorado, for shooting and looking for brass. My favorite place is between Woodland Park and Deckers, CO in the Pike National Forest. It is not an organized place and is very popular; therefore, there is a lot of brass. Although commercial ranges are more convenient, I prefer national forests because I can turn a brass hunting and shooting trip into a fly fishing or camping trip or a small game hunting trip or all three.
The hand gun brass I find most is 9mm. The handgun brass I find least is 10mm. In fact, I'll bet I can count the number of 10mm brass pieces I have found over the past 6 or 7 years on one hand.
I don't know where you live or if you have access to public land areas but that would be my suggestion for finding brass and for shooting. You can take your large tarp, spread it out completely and recover probably 100 percent of your spent brass.
The problem we're having in Colorado with these easily accessible and very popular public land shooting areas is, TRASH. People take televisions, old computers, refrigerators and all sorts of target material then most people are too lazy to pick up their trash. The Forest Service is clamping down on these areas by limiting the places where you can shoot or closing them.