I just 'inletted' a B&C #2998 stock for the PTG DBM Sunday; the total inlet job consisted of using a 5/8" endmill to extend the front tang inlet by .015". Yes, I have a vertical mill, but the same thing could easily be accomplished with a Dremel and a little careful cutting. Point is, the inlet for the OEM BM/floorplate uses the same tang width as the PTG DBM, so there are no angles or radii to deal with. After that single simple cut, the DBM fit was nigh-on to perfect, and the metal was flush with the stock bottom contours.
The downside to the way the PTG & B&C #2998 stock go together is that the new HACT trigger shoe sits a little high in the PTG's tg. Everything fits & functions as it should, including the bolt stop, but the tip of my finger is kinda low on the trigger. It's the same story, though to a lesser extent in the McM A5 I used the PTG DBM in...continued below....
I also used PTG DBM on a Howa build in a McM A5 stock a month ago, and found there was very little work needed to get it to fit nicely. IIRC, I spent about 30 min. figuring out where material needed removed, and accomplishing that with the mill & a Dremel. McM was going to do the DBM inlet for me when they built the stock, but PTG was way later than they'd estimated in getting their DBM out. When McM called to tell me they were ready to do the inlet on my stock, I told them to go ahead and do it for the OEM BM, since I had no idea how long it'd be before PTG could get a DBM unit out to either me or McM.
Whatever the reason for the high trigger issue (could be mostly due to the new HACT trigger), feeding with the PTG & 260 Imp 30* on the Howa McM A5 is excellent, using AccurateMag or AICS 5-rd 308 mags.
Comparing a Timney Howa trigger to the new HACT model, the Timney shoe isn't any longer than the HACT's, and Timney's literature states that their original trigger won't fit the newer Vanguard II rifles, which probably means it won't fit Howa's with the HACT trigger. Need to call Timney for clarification on this point. It's not really an issue for me, as the HACT will adjust down to just under 2lbs, and at that weight, is so close to the feel of a Timney, there's very reason little to spend the extra $$ on the Timney. What I need is a longer trigger shoe to work with the PTG DBM, but what's the chance that anyone would go to the expense of developing & marketing something like that?