I've been using a Redding Instant Indicator for my .308 cases. Easy to use, repeatable and not any real technique for consistent measurements. I'm just starting to load .338LM and need a comparator/bump gage and Redding does not currently build a .338LM II. The RCBS Precision Mic Headspace tool looks pretty good but no .338LM offering. It seems that about the best I'm finding is the Sinclair tool. Any other recommendations?