I recently decided to reload for .308win after getting into a PA10 from Palmetto. I've put together components including Alliant Reloder ts15.5 powder. It's a new powder on the market without much load data available yet. I'm comfortable working up a ladder test, but haven't done so with an AR before.
Any advice on how best to judge pressure in AR loads or maybe even some advice on this new powder? I plan to shoot 168smk from 18" barrel.
Since ejector marks are pretty common on gas-guns, I look at my primer - flattening or gas escaping. Additionally, assuming you are starting with a mild charge, determining where the case is ejected as you increase your load can provide more data(though not completely trustworthy depending on your gas and buffer system). A chronograph will help too - if you're seeing extreme velocity for the given bullet weight and barrel length, it's likely that the pressure might be too high. On the topic of settling on a starting point, I would use Alliant's data to determine where the burn rate is, which looks like it's on their website. They also have recipes too, it seems.
Thanks guys.
Ejector marks and, to a certain extent, extractor marks, primer flattening, flow, or piercing, and sticky extraction. If you have an adjustable gas system, consider closing it completely (giving you a straight pull bolt action) while doing your load development then adjusting it for cycles of function once you find a load that the rifle likes.