Without some form of strain gauge on a rifle and relying on the practice of reading pressure signs such as brass flow, badly flattened primers, sticky bolt lift, etc - how do you really know when you've exceeded the realm of sensible pressures? Case in point - Barnes loading data for CFE-223 is quite energetic in 308 Winchester. Their current published data on the site shows 2877 fps from a 24" tube which is fast for a 168g bullet in a 308 Winchester. My rifle has a 20" Rock Creek 1-11.25" tube. After doing some tinkering with seating depth, 1g under the max charge I'm getting an average of 2712 fps with standard deviations in the 7 fps range and groups in the 0.5" to 0.6" range.
I've been tinkering with 308s for years and this load is quite a bit more energetic my actual speeds I've obtained with IMR 4895, Varget, IMR 4064 and RL15 in several other shorter barreled 308 before pressure signs started to appear. Extraction is just as easy as opening on on unfired case, no ejector marks, or flattened primers. Is this just a case of that particular powder just generates impressive velocities in the 308 win with heavier bullets? I'm just trying to understand if something seems too good to be true - is the truth that I'm running significantly higher pressures than I think I'm running?
