I have a matched billet upper and lower I need to turn into something. I currently have 3 ar's 1-16" carbine (my go to), 1-10.3 300blk sbr, and 1-18" precision build. I have recently sold my 16" carbine and it will no longer reside in my safe after next week so I am leaning toward building a replacement for it but go with a pinned 14.5 stainless 1/7 barrel instead of the 16" 1/9 that I own now. Since I have equal faith in my 300blk sbr and plenty of ammo for it I have no problem designating it as my go to should I decide to build something a little more fun. So my question to you is what route what you go to build a nice matched billet set? Everything I use will be "tier one!"(LOL) so price is not an issue. .50 beuwolf, .450 bushmaster, pistol caliber carbine, 6.5, 6.8, what would be a cool build to you? It will likely end up being a pinned 14.5 carbine like I stated but am open to ideas. Thanks in advance for the inspiration!

I love my 9mm build. Super cheap to shoot. I run uzi mags

I like the idea of a pistol carbine the only thing that is really stopping me is that I would sbr it with an ~8"ish barrel and I do not have the patience to wait a year for the paper work. It's not out of the question but I am definitely hesitant on that one.

6.5 Grendel. The most performance you can get from the AR15 frame, across many different applications, with factory ammo support.

I know the 6.5 is considered to pack the most punch and tends to be considered the longer distance caliber in this platform. Is there any negative side to running it in a 14.5 barrel vs 18,20, or 22? Like substantial losses? I only ask because I already have a 18" jp barreled rifle that I use as my precision rifle for punching paper and don't really want to build it a big brother. Still not out of the question because I am a fan of the cartridge.