The no recoil lug thing really mystifies me. Going with a proprietary tenon spec/coned breach isn't a huge deal as Ultimatum = IBI so they can offer their own prefits and honestly, coned breaches feed quite well but not having a keyed or pinned lug is just bizarre. I get the cost savings of not having an integral lug (you start off with a smaller chunk of billet and there's less metal to machine) but the added cost of having a "key" for the lug (like ARC does for the Nucleus) or even just pinning a lug (like you'd have a smith do for a R700) has to be very minimal but totally avoids the annoyance of having to buy/build a fixture to align the lug whenever you want to swap a barrel. Just a really strange design choice, imo.