Modern Monster Hunting Guns [XM500, MICOR Leader 50, etc.]

[Icelander]

Do we have official GURPS stats for compact rifles firing anti-materiel rounds, like the Barrett XM500 and MICOR Defense Leader 50, both in .50 BMG?

I'm primarily wondering what the shorter barrels do to GURPS Acc, i.e. whether breakpoints for -1 Acc should be at 24" barrels, 20" or 17.6" barrel for the .50 BMG. All of the above are rated as Bulk -5 and Acc 5 for 5.56x45mm and 7.62x51mm, but the .50 BMG might require a longer barrel by default and count as 'carbine' in anything 20" barrel and shorter.

I'm also wondering about Rcl and ST. The M82 statted in High-Tech is damn heavy, has a floating barrel and a pretty good muzzle-brake. Are lighter .50 BMG rifles harder to handle, resulting in higher Rcl and ST? Does not having a floating barrel and a muzzle brake translate into higher Rcl and ST?

I'm also wondering if there is a realistic way to custom-build or even order a carbine length weapon (16" barrel or so) that is handy for entry but chambers a round substantially more effective against supernaturally tough threats than the 7.62x51mm. Semi-automatic, magazine-fed, at least 10-rounds.

Ideal chamberings would be .408 CheyTac or .416 Barrett, if those can work in such short barrels, but otherwise anything that gets Dmg over 7d pi+.

.450 Bushmaster looks pretty practical for a civilian monster hunter, though I don't know how much Dmg you would get. .45 Raptor might be even better.