OK ... 6mm ARC it is. I called Radian today and asked if they're going to offer a bolt/BCG for the 6mm ARC but have yet to hear back.
@js8588, thanks for that build list. The Radian Talon ambi safety is already on my list along with one of their forward assists. I always run TUBB flatwire springs in my ARs so that's on the list too. My friend had put together a list of parts that he was planning to buy and kindly forwarded it to me. I'm not up on the latest and greatest so it's helpful. I have three POF rifles so am familiar with that system but don't plan on a push rod type upper (a.k.a. piston upper) but he was thinking of going that way. Here's his list of the parts he was planning to add with his comments in ().
Buffer system:
https://www.jprifles.com/buy.php?item=JPSCS2-15
(A standard buffer is fine but I really like these JP captured units. I think they are a really nice upgrade although a bit expensive. They are a little cheaper from places like opticsplanet etc.)
Forward Assist:
https://radianweapons.com/accessories/rifle-parts/forward-assist-aluminum-black-anodized-ar15
(Matches the Radian logo already on the takedown pins. )
Safety:
https://radianweapons.com/accessories/talon/talon-ambidextrous-safety-selector-2-lever-kit-ar15
(Best safety selector on the market in my opinion and I've tried quite a few of them. I would get the (long) length levers on both sides if you can, I think that is the best option especially using a 45 degree throw. )
BCG/Gasblock:
https://suparms.com/collections/ret...tem-rifle-length-solid-melonited-low-pro-ar15
https://www.srcarms.com/shop/all-products/sharps-xtreme-perfomance-bolt/
(For this build I wanted to try out one of the Superlative arms piston kits as I thought it would suppress well. With all these parts I was also trying to come up with a build that would be a good suppressor host and have the least amount of gas blowback coming back at the shooter. The kit comes with the gas block and carrier but doesn't include an actual bolt, cam pin or firing pin. I was probably going to order one of these Sharps enhanced bolts to try with it since the design seems interesting. A POF roller cam pin would pair nicely with it. Then you just need a firing pin and firing pin retainer pin, any option would work for those. )
Alternative DI option: https://radianweapons.com/accessories/rifle-parts/enhanced-bolt-carrier-group
(If you didn't want to go with the piston system this would be a nice alternative to go with the rest of the Radian parts. Or you mentioned having an extra POF BCG and I'm sure that would work great too. Then you can just pair it with whatever gas block you want, I like the look of the Fortis ones personally to match the aesthetic of the rifle.
https://fortismfg.com/accessories/gas-block/ar15-fortis-low-profile-gas-block)
Barrel:
https://faxonfirearms.com/match-ser...ngth-416r-nitride-5r-nickel-teflon-extension/
(This was the barrel I was planning on using. I like the 18" length for a SPR type build and it seemed like a nice weight for a heavy fluted profile. That being said a 18" Proof barrel would be really nice too but I wasn't willing to spend the extra money for one.)
Handguard:
https://www.rainierarms.com/rainier-arms-m-lok-switch-5-56-rail/
(I was planning on getting the 15" version of this handguard as it's the longest they offer. It's made by Fortis for Rainier Arms. I think the style matches well with the receiver set and it also has the "SWITCH" mounting system. That means you can quickly remove the rail if you want with no tools. You take it on and off by releasing a throw lever on the bottom. This was an important component in conjunction with the Superlative adjustable gas block/piston system. Normally when you look at piston guns the piston has to be at the end of the handguard so it is accessible for cleaning, or a cut out has to be made in the handguard so it's accessible. With a quick removable handguard it can be longer and extend past the gas block but still offer easy access to the gas piston for adjustments and cleaning.)
Muzzle Device:
(Whatever attachment system you have in mind for the suppressor you plan on using. I was going to do a Surefire Flash hider but of course that doesn't make sense for your build. )