Very interesting. Some sources say 7° others say 8°. My gauge is clearly marked 7°35' but the mandrel measures 7°30' not that 5' of angle makes much of a difference. Thank you for the information about full-length contact being critical.

One thing I've noticed on my mags is that I will get different presentation angles with one vs. three or more cartridges loaded. I'm assuming that the three or more presentation angle is the critical one but I'm curious as to the reason for the variance