Starting my work up for a new AR rifle build in the coming year, and while I have a goal in mind, I’m still finding myself second guessing certain elements.
I thought this would be a good opportunity to catalog the process from beginning to end, and hopefully serve as an information repository for people looking to achieve similar goals.
I have enjoyed the flexibility my MDRX affords me in the range of jobs it will do, but with spare parts support becoming increasingly difficult to secure as the new DT models take over, coupled with the weight of it, I thought it was time to try and capture that same flexibility of performance in a more long term serviceable rifle.
Primary goal: a light and portable SBR that is capable beyond the normal engagement distances of a full length 5.56, despite being close to PDW size. (Keep the suppressed length as short as possible)
Secondary Goal: Develop a heavy for caliber subsonic loading that may or may not cycle (I am unaware of any such item in either potential caliber of choice)
Calibers: 6 Arc vs 6.5 Grendel. Both are interesting, however not as much info is out there regarding 6 ARC’s short barrel performance. 6ARC is the preferred of the two, mostly because of factory load availability (and it being easier and cheaper to machine custom projectiles for), but reloading is on the table if the performance increase justifies it.
This is intended to be a true fighting rifle build, that will be used for competition but also as a true “if you only could grab one rifle and go” build. part selection favor will go towards parts with proven durability track records or are manufactured by companies that must follow rigorous AS9100 quality standards because of contracts they hold.
Parts that are somewhat set in stone:
- Use of a Precision Firearms barrel cut to a specific profile shape to allow use of SPR collar type suppressors, either the upcoming OCM6 or AEM5-30k. I am however open to suggestions if there is a better option for minimizing suppressor length.
- March 1-10 shorty for the optic. I simply cannot see a reason to use a fixed parallax LVPO when part of the goal is effective engagement at 1000yd
- A high strength rigid rail for NV device mounting and potentially a 40mm launcher (because NFA toys are fun). This so far has me looking mostly at the DD RIS 2/3 and URX4
- Mags will likely be the Geissele 30rd which are supposedly fine with either 6 Arc or 6.5G
Am I setting the bar too high? Maybe, but I think the tech exists out there to pull it off.
The first question I need opinions and help on is real-world data on 6Arc vs 6.5G performance in short barrels (12.5” or less)
6 Max was considered and discarded because no one makes a decent capacity magazine for the caliber at all
