I have an Oryx factory stocked version of the 6.5G Grendel version. I rate it as an excellent out of the box rifle, good layout, pleasant to shoot, excellent ergonomics, and for a factory product pretty accurate. I have it down to just on half-inch 100 yard 5-round groups off the bench with 120gn Scenar-Ls and will shortly move onto the 120gn SMK, Lapua, Hornady and Sierra 123s and the Berger 130gn Tactical AR-Hybrid to see how they do.
The synthetic magazine is unimpressive, feeds OK in my very limited use, but as I single-load most rounds this is marginal to me. Unlike some DBM magazine fed actions, this one works well and smoothly single-shot simply dumping the round through the port and it feeds the Grendel smoothly without effort as long as it's somewhere aligned with the chamber. Magazine fit and retention are good in the Oryx stock with a positive and reliable, if rather heavy, release lever.
The Mini action is smooth. light, and unsurprisingly at 0.9" shorter than a standard short action benefits from the short bolt throw. All the basic functions such as extraction and ejection are fine, the latter about right for range use - positive but not so much so that it dents case mouths or throws them out feet into the long grass.
In prone marked target shooting off a bipod, the stock pull-length is too short for me, so I've just acquired an MDT butt spacer kit which should rectify that. Despite a lot of experience with chassis stocked and tubegun F-class rifles, I forgot that the scope needs to be mounted high for a comfortable hold / head position on such inline layouts, so a ring swap is about to take place. Finally, although crisp I find the factory HACT trigger too heavy. I bought a replacement spring to lighten it mail order from some guy in Australia, so I'll try that - it's supposed to take the trigger down to around 2lb break. (There are YouTube videos around too on DIY trigger lightening jobs by cutting part coils off the OEM spring.) If the trigger is still on the heavy side, aftermarket replacements from Rifle Basix and Timney for the standard Howa short action fit according to posts in the 6.5 Grendel Forum .... but won't be accommodated by the slot in plastic stocks. It's said though that the Oryx has a large enough well for the trigger assembly to take these triggers making it a fit and drop-in upgrade.