Jason, this was with R/P brass, cci 250 primers.
Esox, you ask what I am trying to accomplish. In a nutshell, I want a 160 bullet at about 3000 fps plus or minus a few and stellar accuracy. This is the reason I have a 7mm rem mag. Every manual on the planet suggests it possible. When I had the rifle rebarreled a couple of years ago, I decided to go 26" so that I would have a better chance of hitting those "magic" numbers. I am not trying to "hot rod" my rifle. I just want it to be a magnum.
I already have a 7-08 that easily pushes 140 grain pills at 2850fps. I want my magnum to act like a magnum, not a .280 rem or powder hungry 7-08.
I had never used a chronograph until a few months ago. In the past, I always watched for signs of pressure and shot for accuracy. Now, I have pre conceived ideas of what my rifles should do velocity wise and I am not interested in shooting a rifle that isn't reaching its potential. I figured that I could approach my loads with caution and try to maximize both velocity and accuracy while remaining safe. Am I wrong to do this?
FH
FH: No you aren't wrong and I feel exactly the same way.
We have to remember that when we check several sources and see a certain range of max velocities from a cartridge, they will generally only be acquired at the top velocity potential for that case,and the only way we will get it is to use maximum,but safe, loads.
I figure, if I want a 280, I will buy a 280;and I will not try to make it a 7 mag....most people who try do this are confused;they simply bought the wrong cartridge for what they were trying to accomplish.
When I have a rifle chambered for a given cartridge that only shows great accuracy at loads that develop sub standard velocities for that cartridge, I generally suspect that something in the system is out of whack;that the rifle is not well nor properly assembled....I fix it or get rid of it.
Not all rifles will respond the same way to a given bullet/powder combination.I had one 7 REM MAG years back that doted on 7828 and 160 Partitions and would give about 3100 fps with no problems and I hunted that rifle everywhere until the barrel wore out....but over the years I have learned a couple of things about the cartridge,and one is that when I see a 160 gr bullet hit about 3050 or so with good accruacy, I stop right there as the case is not really capable of safely providing much more.
It is not unusual for a magnum capacity case to deliver better accuracy at max pressures and velocity than with lighter charges....sometimes they will deliver better accuracy when the charges are TOO hot for steady use, which might be where you are....but like Mule Deer say, hitting your velocity objectives is entirely within reach; if 7828 does not do it for you, we have a wealth of new slower burners that work well and will give you those velocities you want very safely....Retumbo is among them;today the first powder I reach for in the 7 RM is RL 25,which is an ongoing experiment but has delivered fine accuracy and good velocities for me so far.
I would do more testing with the retumbo at 3070 fps;get off the 100 yard line and shoot from at least 300 yards,because 100 yard groups frequently do not tell the whole story.