I have always valued Seafire's contributions and respected his opinions. But in this case, I disagree.
The absolute best and most dependable "pressure indication" is a dependable chronograph. No, make that second best. The best is a Pressure Trace device. But they are still a bit spendy and complicated for any but the most serious of hobby reloaders.
Pressure times time does equal velocity. For example: You can not hit 60,000 psi in a 30-06 using H4831 with a 150 gr bullet without getting well past 3000 fps.
On the other hand if you have hit 2900 fps with a 180 gr bullet in the 30-06, you are at or over max pressure no matter which powder you have used.
We have been discussing traditional pressure indicators on this forum for many years. We have compared pressure ring expansion, case head expansion, primer flattening, primer cratering, The closest thing to a consensus is that none of these indicators can be depended upon to appear before your load has already passed Into the danger zone.
I measured and recorded case head expansion for several years. When measuring 20 identical loads in virgin brass gives CHE reading from .0005 to .0025 in cartridge after cartridge and caliber after caliber, one begins to understand what Denton means when he tells us the practice produces too much noise to be of any real value.
My reloading practices evolved to this:
I pick my cartridge and bullet, then with the assistance of the loading manuals I choose a powder which will produce maximum velocity for the bullet chosen and load to 95% to 105% load density. I love compressed loads! One of my favorites for the 30-06 was 63 gr H4831 in Lake City 67 brass with a 165 gr ballistic tip.
After selecting cartridge, bullet, and powder, I set up the chronograph and grab a tablet of graph paper. Starting at book minimum, I graph velocity vs charge weight. You are looking for a nice straight line "curve" with dots not straying too far from the curve. When dots start departing from the curve at the top end, whether above or below the line, the load is at maximum pressure.
Of course, one will watch velocity. One knows what velocity to expect at SAAMI max pressure, from his load manuals. There is no free lunch. If your velocity is above max speed shown in the manual with your powder,then your pressure is also above max.
With my rifles, the rule has been with very few exceptions, they are slower than the book suggests. I often load several grains above book maximums. But as long as my MV is in line with book maximum, adjusted for barrel length, I know my pressure is okay.
The one traditional pressure sign I depend on is tight primer pockets. If the primer still seats with good resistance using my Lee Auto Prime after ten reloads, it is definitely a safe load. If the primer starts falling out after six or seven loads, it is too hot.
Last edited by Idaho_Shooter; 04/03/18.
