How about something like this:

https://www.gunsinternational.com/g...ot-imp-cyl-mod.cfm?gun_id=101418699#lg-1

The Miroku OU's (and sxs as well, if you don't mind being odd man out and shooting a sxs at SC) are very reliable and very good buys on the used market. Likewise, you might also pick up either an Ithaca-imported SKB or a Citori, older versions without choke tubes. You will struggle to find anything longer than 28" barrels, and chokes will often be M/F which you'll want to open some for targets. I have no problem shooting 100 sporting clays with 16ga sxs that weigh 6 1/2# or less, although that's mostly with 7/8 oz reloads, using some 1 oz factory loads for longer targets. Any of the guns I recommended above will work fine for you all day shooting 1 oz 12ga target loads.