I'm not new to hand loading, just to precision loading. My current problem is this; I'm loading 7mm rem mag using three bullet types: Berger 168 VLD's jammed (tried different jumps, but they definitely are way more accurate with 1-2 thous jammed), Nosler 150gr ballistic silver tips (the most accurate load for my TC Venture printing under .5" @ 100 yrds) and TXS 120's. Here's the rub: I just purchased a Chrony Beta Master and tested the loads. My SD is way out. 138 to 174 fps per string deviation with the Bergers using 61.5 grains IMR 4831 at an average fps of 2850, and exactly the same (174) for the Barnes (2971 ave. fps). I'm weighing the charge with an RCBS digital powder scale/measure and have compared the resulting weights with a mechanical scale which confirmed the weights. I'm using Federal match primers and Remington cases and sort the cases in groups per the case weight. I can't figure out why there's such an extreme spread. The only wildcard might be the case neck tension. I'm using a full length Hornady sizing die which is not needed with the bolt gun. I've ordered a neck size only die which is soon to arrive. The case neck tension with the full die was weak at best, allowing me to move the bullet with a firm grip of my fingers with effort. I can understand the velocity changing from a cold barrel to a hot barrel, but have no idea why I'm getting such a spread. What do you think?