For mounting directly in a barrel dovetail, the replacement sight blade will not fill the dovetail, side-to-side as it should, unless a "wide", "W" , or .530" width sight blade is ordered.
FWIW, the narrower "medium", "M", or .340" width blades are for sight ramps.
Because the XS peep is a top-mount receiver peep, you're going to need a replacement blade that's at least .500" high, if not taller.
XS has excellent tech support, so why not give them a ring with your rifle's particulars, and ask them ?
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