Years ago I bought an original 20GA SXS circa 1790 that had gone through a drum/nipple percussion conversion. I bought it specifically because I wanted a SXS flint and it looked like an affordable way to get one. HOWEVER, my intention was to NOT do anything g that could to be put back the way I got it. As it turned out, (and as I suspected she I viewed the pics prior to purchase, the little L&R Bails locks were pretty much a drop in, just had to do some SLIGHT relief in the mortice to accommodate the mainsprings. I then made SS touch hole liners to fit the existing drum holes and had my SXS flint that I can put back to the way I received it in the time it takes to unscrew the touch hole liners, screw the drums back in and put the old locks back in. Point being, if you REALLY want it back to flint, there are ways to do it without losing the guns true history. I got lucky in that the L&R locks fit but no matter what the original locks look like, with some judicial "massaging" it is likely that replacement locks can be added without butchering the originals. I believe MNOST conversions were in the form of a drum/nipple arrangement which is easy to replace with a touch hole liner. However, if the breeches were converted in another fashion, this might be problematic. Unlikely to be insurmountable but might take a little more creativity to reconvert without losing the guns history. Just something to consider.