I’m using Viht n160 on a .243 100gn Sierra pro hunter in a 1in 10 barrel. Now after multiple searches looking for load data on Viht there are conflicting data it appears some time in the past the Vhit reload data dramatically reduced the max load however several people they used N160 for years and ysed there original load that exceeded the latest data with new powder and not seen a difference. I looked at an article posted oct 2013 http://roestalker.co.uk/large-deer-legal-243-win-load/. Taking the same principle starting at 39 gr and moving up in increments to 43 gr. Well I started to shoot starting at the 39g when I shot the 41 gr their looks to be start of pressure signs on primer. Primer flatens out ok but on the firing pin indentation there is a ridge forming on the outside edge. I should know what the technical term is however I don’t sorry. So I have not gone further to 42 gr and 43 gr. Coming back to my question I have two conclusions possibly false conclusions. The first is that the latest load data is correct and I need to keep within those guidelines. My second is a another question that I can’t really find an answer to. I used a neck size bushing of .268 , this was probably my second choice as I was would have preferred .269 it was only down to a guy having one for the right price. So does neck size have an impact to pressure, I would imagine it would and I don’t have the information to substantiate my thoughts. If id does could this be the reason that pressure signs are starting to show. I have not chronographer the loads yet. I was going to test the group size then pick a load and test speed. Anyway this has been a bit of a ramble , however thoughts anyone is it powder max load data, or possibly neck Size adding to Pressure signs.