They are hand loads I developed. I wanted to make a clone of the Black Hills Mk262 5.56mm round. It uses the Sierra Match King 77gr BTHP, and flies at 2750fps. I also run the rifle suppressed with an old Surefire.
Couple of folks have mentioned how the RAR 556 would make an inexpensive truck gun. Somebody followed up suggesting a folding stock would make it even better. And someone else mentioned Sharps Bros Heatseeker. Okay, here's my take on all that, although I blew "inexpensive" all to hell in the process.
A RAR 556 in the Heatseeker chassis, a Matador Arms Sidewinder folding mechanism, a Phase 5 mini stock, a Primary Arms Slx 3X micro prism, and assorted AR 15 pieces out of my parts box. Folds up into a Bulldog 29" discrete carry bag that fits behind my truck's back seat. I was able to shoot 2 to 2 1/2" 100 yard groups with IMI 77gr Razorcore and OTM LR rounds of a bipod on a concrete bench. Not as impressive as QuietM4's groups, but will work for me.
Although the RAR 556 can use AR ammo and mags, it doesn't run nearly as smooth as the regular AR 15. It'd be interesting to take a carbine class with it just to compare.
I've REALLY got to get another hobby.
The 3 low shots were my first sighters. The next 7 were the ones in the general vicinity of the bull after sight corrections.
I have shot my buddies' Predator in .308 a bunch - it shoots way better than it's price point would suggest. As far as the Mossbergs go - I had one of the original MVPs and hated it - traded it. Mine had a horrible bolt feel, wobbly mag, and wasn't very "accurate." Glad I got it in a trade and didn't actually buy it.
I had forgot that Mossberg was making rifles till a few months ago I was at the range and some dude shows up fresh from the store with a Mossberg rifle of some sort in .300 winmag. Takes it out the cardboard box, pulls the bolt back - and a bunch of parts ejected. Couple RSOs helped him find the parts put it back together. Reminded me not to buy their rifles yet. Lol.
1st rounds at distance were at 645 yards. Didn't see target impact splash and no dirt kicked up around the target. Wasn't sure what I was hearing for an impact. Had a spotter verify they were hits. Had decent success at 800'ish and 2 out of 10 at 1040.