Seriously, a .410 gives you a smaller pattern ( maybe 18" instead of 30" ) and with only 1/2oz of shot ...its not a gun for a novice. But it will tell you if your fundamentals ( swing, watching the target, follow thru ) are really in sync... We have a number of guys at my club that will easily run 100 straight with the .410 ...and they hit them hard !
Heck I don't have confidence in any of my guns somedays....but I do know that I get away with some sloppy moves now and then on a target with a 12ga....
But most of us shoot clay targets for fun anyway ...I did manage a 96 a few weeks ago in Skeet ....( 24, 25, 25, 24 ) ....for one of the best days I've had in a long time with my 12ga Citori XS Skeet ...and heck, I'll probably hold that day over my squadmates for at least 3 months....
But as we all get older, and I'm only 62 ...we have orthopedic issues ..that make picking a gun and gague more important (like the shoulder rebuild I spoke of above ) and somedays I just can't handle a big 8 1/2 lb 12ga gun - even mounting it hurts (not just the recoil )...its the weight that takes a toll on my elbow and shoulder. That's why I still think a 28ga is a good idea...especially in a gun that might only weigh 7 lbs...so don't overlook a gun like the Browning BPS Hunter model in 28ga ...with a 28" barrel....its an affordable option as well. They're selling new in box for around $ 600 in my area. ( its style is classic / nice wood / blued barrel ...)...
http://www.browning.com/products/cat...id=012&tid=211
or even think seriously about reloading for that 20ga ...with some 3/4 oz loads...( basically make it like a 28ga ).