Thread: Lower than expected velocities

Originally Posted by csmiffy

Cases could be a factor?
A bigger volume case could suck up a couple of grains of powder compared to another case.
GPmac have you and others suggested though that in the absence of sometimes erroneous pressure signs it more to do with the velocity as yiu can't have the velocity without pressure?
Stand corrected if I've got that wrong as I don't do bugger all reloading and have only just bought a chronagraph

Greetings @csmiffy,
You are quite right in that a lighter case, with more capacity will result in lower pressure but how much is another question. I have a test loaded for my .308 with light and heavy cases but have yet to chronograph them. I suspect the difference is less than some think. The BM8208 loads I mentioned in my previous post were loaded in heavy cases but were still well short of the Hodgdon velocities and more in line with later data from Handloader and Hornady. The problem with "pressure signs" is that when they appear, assuming that they do, you are well over the specified max pressure and have used up most of the safety margins. I have found that max loads may vary between data sources but the velocities are more constant. The data still needs to be for the same or similar projectile especially for the new whizzo ones around today.
Regards Grandpamac.