Tinker,

I mean I've never seen a rougher bore on a shotgun ever, & I'm primarily a vintage sxs guy.

Some pits are so big & so deep that my skeets bore gauge gets hung up.

Nominal bore is 0.665"
There is no choke whatsoever
Chamber is very nearly 2 3/4"
minimal wall thickness seems to be a healthy 0.040, but that excludes pits as the "ball" on the inside arm of my wall thickness gauge is too large to sink into the pits.

I've weighed it on a proper scale & actual weight is just less than 4lb 12oz

Obviously I will need to hone it whatever the decision is, so I will go slow & measure & watch & maybe it will clean up within my comfort parameters (but I'd bet against it).

I'm leaning towards a 577 BPE, my thinking being the larger the new bore the better the weight & balance of the gun might be maintained.

I'd like a 20 bore rifle (slug gun) for some of the areas I hunt deer, but the gun may be a tad light for that.

Thanks for your input.