Mike, I've already fired 11buckshots, and about 4 slugs. She kicks like a freaking Mule. So I decided to get the "AA" ammo that CASS uses. Hopefully that will reduce the shoulder and knuckle soreness, lol.
Not all AA loads are the same. There are two that would be appropriate for use in your gun. The first is the AA low noise, low recoil load. The second is the AA Xtra-lite, in the one ounce load. Both have low enough pressure for use in Vintage guns, the other AA loads's have pressure that is too high.
Since DocDrew pointed out the crolle, here's a pic of what Remington model 1900 Damascus looks like:

Regards
Ken