Mine is a dedicated .300blk subsonic. Began with a snowflake stripped lower from Spikes.
My 6.5” barreled 870 for reference. The brace is a collapsible TailhookMod2 -have a 3-lug attachment for the Octane9. Barrel length is 8.5 but the 3-lug adds an inch or so. Trigger is an Elftmann. The best trigger feel of any firearm I’ve ever tried. Get one.
I don’t use the Magpul mags anymore. They don’t work perfectly with .300subsonic bullet profile. The Daniel Defense mags are 100% though.