Is the failure to feed consistent or is this an intermittent problem? (and I don't just mean with the OP - is this being reported by others who have done the B&T adapter conversion.)
Of the five mags I have, 1 was perfect, 2 work 95%+, the other two are about 50% chance of getting through a mag without FTF. Oddly, the FTF are in consistent, yet different spots. IE, round 1 for one mag, rounds 6 and 8 for the other.
Speaking strictly about the CZ 858, after the milling is done and the feed ramp is mostly removed, will the CZ propriety mags still work or are you now bound to using the B&T magwell adapter and the XCR mags? (I understand the desirability of the 10 round mags over a pinned at 5 round CZ mag.)
Wolverine says they will, I never tried.
Is the modification of the feed ramp a necessity for the fitting of the B&T adapter? Can the B&T adapter be redesigned so as not to require a modification of the feed ramp? I haven't seen the B&T adapter - does it incorporate a feed ramp to assist in the loading of the rounds when stripped by the bolt from the mag?
Yes, it is. The mag is too long to avoid modifying that area. The adapter is a box, no feed ramp, nor is there room for one.
What about the XCR pistol 10 round mags - does the failure to feed occur because these mags are being used in a firearm they were not designed for? Can the XCR 10 round mags be modified to fix the failure to feed in the CZ 858 with the B&T adapter and still legally allow a 10 round capacity? (more spring tension perhaps.)
Tweaking the mags (follower, feed lips, spring) will make a difference. I tried lots of different thing with them. I did notice that due to the extra tilt the follower needs to have when loaded, the rear follower leg would sometimes get caught between spring coils.
