I've got a Ranger 7 from the SDN6 conversion program (took about a month turnaround for me back in late '24), and I've been digging into end cap options for similar reasons—wanting that recoil reduction on a bolt gun without going full TBAC setup. AAC's proprietary front cap threads are indeed a headache; their response to inquiries is basically "hands off," which screams they're prepping their own accessories lineup. From what I've seen on their site and dealer listings, they've rolled out replacement end caps like the .30 cal flat and a 6mm flash hider variant (machined from 17-4 steel, nitride coated, works on both Ranger 5/7), but no dedicated brake end cap yet. The flash hider might help a bit with muzzle rise on rapid follow-ups, but it's no true brake for taming .300 WM or similar.
If you're set on an Anchor-style brake, RecoilX could be a path if someone measures the threads—maybe hit up a gunsmith with AAC contacts or reverse-engineer it (at your own risk, warranty voiding and all). Alternatively, I've heard whispers of custom shops like those adapting for Surefire or Dead Air doing one-offs, but nothing off-the-shelf for Ranger. TBAC's RR system is killer for bolt guns, but porting the Ranger directly might void it; better to wait for AAC's play or swap to a Dominus if you're multi-hosting.
OP, what's your primary caliber and barrel length? If it's 6.5 or under, the 6mm FH cap could be a stopgap. Anyone else get a thread pitch confirmation or try a DIY adapter? Let's pool some data here.