With my barrels backed off I have some end shack with all mine. Some of that goes away after cartidges are in the chambers. With my barrels set to 3ths and empty chambers it has no persevable shack.
I guy a while back had one that was loose . He bought some shimmimg washers from brownelss and that tighted it right back up.. Look it over again and take a micrometer if you can. If it looks good it probably still worth buy'n. Also besure the cylinder pin is tight.