Sorry "old school" retro here just can't get into all that "crap"
hanging at every angle.
XM177, CAR15, pencil barrels, and others
but do have a few modern flat tops but...still no crap hanging only
sights and optics.
a very..very.. old picture
But to answer the question. In 556 I like a 14.5, 1/7 twist with midlength gas, flat top upper, slim mlok handguard with a primary arms acss retical lpvo.
300 aac I'm an 8" kinda guy and keep it suppressed all the time. Light weight handgaurd, and an acss 300 retical that ive dialed in for supers and subs plinking.
I see it as those two are 0-200 yard carbines, 300 on the 556 amd anything past that I'm going grendal or ar10. And yes I know 556 62 grain green tip will go 500 yards on a man size target, I do it yearly. But if its time to get it at 300 plus or shoot through cover or concealment I want a bigger round.
My two k.i.s.s. carbines for HD are a 14.5 bcm with an aimpoint, and an old colt rocking fixed irons. For my OGs you know about house clearing with just using the front sight post.
In all seriousness, I like them all but theres not a one does all. Pick what your needs are and set it up around that. Bailing out of a number with a m16a4 with a fixed a2 stock was comical at times looking back at it.
18" SPR barrel, 1-8x optic, AAC brake with blast mitigater. It's heavy, but it's as close as I could get to the military SPR without dropping another $1.5k. Very accurate with everything from 55gr fmj to 77gr jhp.
The other is a 14.5" M4 barrel, carry handle upper receiver, AAC brake with blast mitigater. Not as light as my 14.5" 3-gun rifle, but it is very handy and gets the job done.
I have a few more configurations, but these are the two on 5.56 that I won't ever sell.
They are very versatile and accurate enough for longer distances.
My recent build was inspired by the Troy SOCC.
(Special operations combat carbine). But I wanted a longer 18” heavy match barrel. The ergonomics/profile is similar to the HK33.
The one on the top is a Rifle. 18” 1:8 twist fluted hbar. 15” mlok rail. Calvin elite trigger , 1-6 Lpvo and a Troy m7 pdw stock. 45 degree offset iron sights.
It’s a very accurate rifle. The vortex 1-6 BCD lines up perfectly with the ballistics of a 62 grain load.
I have built a couple semi-auto mil-replicas in the past, pretty standard A2 and M4 variants, but always kinda wanted to build an N23 View attachment 307308