I was really interested in the Mini action when I found out they were going to chamber it for the 6.5 Grendel - not because I'm a fan of the 6.5 G, but so I could use a push-feed action with the correct boltface to build another bolt rifle in 6RAT. I'd done one on a CZ527 carbine in 7.62x39, and though it turned out to be a good looking, good shooting rifle, I never have gotten the magazine to feed 100% of the time. I figured the push-feed Howa Mini would work better, and it does feed the 6RAT with 100% reliability. I didn't do any action truing, just fitted & chambered a Bartlein 6mm/1-8tw light Palma blank for it. Initially, McMillan offered to build a stock on the Sako Varmint pattern, but needed a bbl'd action to model the inlet - and they wanted a $500 fee for the custom inlet. I sat on my hands for several months, having spoken with Tom Manners, who wanted to do something like his EH2 stock in the Mini inlet, but again, he also needed a bbl'd action, and talked me into selling him one of my 6.5 Grendel models. Somewhere in this time frame, Boyds started doing the Mini inlet, and not long after that, McMillan decided to waive the $500 custom inlet fee if I'd send them a bbl'd action. So I sent them a 222 Mini, and in due time, received the Sako Varmint pattern stock, which I used for the 6RAT bbl'd action. About that time, DIP came out with their aluminum DBM, which is a huge improvement over the OEM plastic pos. I did the trigger spring mod, clipping about 1.3 coils off the trigger spring, which resulted in a nice, crisp 1.2lb break. This was better than what I'd gotten with a Timney, so since then, I've done this simple mod on all four of the rifles I've built myself on the Mini action.
I eventually decided that the McM Sako Varmint stock wasn't going to work well for shooting prone off a bipod, so sold it to another Mini owner, and got McM to build me a Game Scout stock for my Mini in 6RAT. This is my favorite Mini stock, though the B&C #1003 is a close 2nd. Boyds ProVarmint w/adjustable cheekpiece is also very good, though the laminate stocks are quite a bit heavier than the lighter composites like the Game Scout. So now, I've got four Mini-based customs - the original 6RAT in the Game Scout, a 20 Tactical in a Boyds Prairie Hunter, a 22 Grendel in a Boyds ProVarmint w/adjustable cheekpiece, and a 6.5 Grendel in a B&C #1003. All four have DIP DBM, the spring-clipped factory triggers, EGW or Warne 20 MOA sloped scope bases, and Bartlein bbls. And all four are good, solid, accurate rifles. The main reason I finally went back to the rifle's roots and did one in 6.5 Grendel was that I had purchased a Bartlein 6.5mm/1-8tw blank in Rem mag sporter contour off their inventory list. The shank of this bbl was too short to hold in a 4-jaw chuck to do the bbl work through the headstock; but since I turn shanks for a Mini action down to 1.090" dia, when that was done to this bbl, the shank wound up being plenty long to allow through the headstock chambering & threading. Haven't shot it a lot so far, but with Starline brass & IMR8208 powder with Lapua 123 Scenars, it's impressing me with its 600yd accuracy. Am beginning to see why so many shooters like the little 6.5 Grendel - though I'm still partial to my old favorite 6RAT, and am looking forward to getting some serious load development done with the 22 Grendel after fall farm work is done & out of the way.
The plastic Howa mags for these rifles remains an issue - there's enough variation in the distance between the tops of the feed lips and the lug that engages the magazine catch to cause some issues in getting action height set for reliable feeding in some stocks. And the mags are way over-priced IMHO. I'd sure like to see someone like Magpul come out with a more substantial Mini mag, even if it would require different DBM to work.
I'd also like to see Howa do the Mini with a 6.8 SPC boltface - there are several .22 & 6mm wildcats based on the SPC case, and this little action is the perfect basis for rifles chambered for these cartridges. That includes the 6 HAGAR - I have an AR15 match rifle/spacegun upper for the HAGAR that performed very well for me - after Hornady began making brass. The early cases I formed using R-P 30 Rem & Jamison 25 Rem brass were fairly accurate, but case life was crap, which I found out after going through a labor intensive process to form 1200 pcs. Though there's not a lot of difference in case capacity between the HAGAR & RAT, I'd still like to have a bolt rifle chambered for the HAGAR, and a Mini action with correct boltface would be my first choice.