I've never seen a Sportster in person but I believe that they come with a different rear sight than the Versa Packs. The Versa Packs I've seen have a plastic sleeve of sorts over the barrel that has a dovetail for the rear sight. Honestly, just how durable is that? Does it actually work well or is it an afterthought by NEF? Do the Versa Packs 22lr barrels come drilled and tapped for a scope base? Thanks in advance.