Just excess material. The kit actually came with a washer to add in that point just to help it sit better but it also recommends trimming material from some points to tighten up the fit. I don’t think it is too much of an issue, the Mosin’s barrel floats and is mounted only at the magazine and receiver.
Noce work. I’ve been toying with the idea of doing that to one of ours. I did a similar project to an Ishapore Enfiled in 7.62 NATO a few years ago. It’s a sweet littl shooter that Ishapore.
Wish I’d bought a dozen wheni had the chance.
I’ve done the same: ATI conversion to one M-N and original restoration of the second. On the ATI conversion the barrel floated high until I put in the washer on the rear receiver bolt, which fixed that problem. I also had problems feeding stripper clips and then getting the bolt to eject properly. I had to take quite a bit of material off the inside of the ATI stock, right at the ejector bar, to give enough clearance for it to work properly. Now both guns work great and the 7.62X54 is a lot of fun to shoot but I’m no longer as satisfied with the .223 AR-15 and wanted a higher caliber semi-auto, so I had to purchase a M1-A (so I ended up spending a lot more than I set out to for my inexpensive rifle).