I would doubt it if it was bored to 28 as most rook rifles just about make .410's. I would suspect that it was made as such. The description fits that as owned by a friend of mine who has one in 32 bore by Westley Richards. The half octogon down to round was quite a common feature on English singles. $700 doesn't sound like a bad price. Thanks for the update. Lagopus.....