Unclenick,
First, the "50 fps" more velocity from my gun was comparing my 22" barrel to the 26" barrel "Custom Mauser" in the "Nosler Manual Number Two." If I try to take into account the barrel-length difference by using QuickLOAD (which also doesn't match my gun's velocities) then I would need to add about 130 fps for my top load, so my gun seems to be getting something like 180 fps more than "expected" from the manual.
The manual used Norma cases, I used Federal. The manual used Remington 9½ primers, I used Winchester WLRs (which might be a lot of the difference). The manual data was shot at 68° F and my data was shot at 75°F. The Mauser has 1-in-10" twist; I think I remember mine has 1-in-9½" twist. My fired case capacity averages 70.0 grains of water. I don't know what the "Custom Mauser" has in the way of chamber dimensions, throat length or bore cross-section, so making these corrections is not possible. The case volume would need to be 76.2 grains in QuickLOAD to completely compensate for the difference in muzzle velocity for the 4" difference in barrel-length alone, so I don't think that is likely to be the whole story.
With respect to being "happy" about the difference, I am happy with this particular load. I load to around 3,000 fps, so I am not at the top of the range in the manual, and the load shoots a little less than MOA, so I am "happy" enough with the accuracy.
In another thread on this forum (
http://www.thefiringline.com/forums/showthread.php?t=370767 ) "Major Dave" was asking questions about what to do when your gun is not matching the velocities in the manual, and I had spent some time thinking about it and trying to post some guidance for him. His situation was that he was getting less velocity than expected with one powder and bullet and more than expected with another powder and bullet, both with same weight bullets in the same rifle. He wanted to know if he could use the second powder with the first bullet and just keep adding powder until he achieved the velocity in the first situation.
"Major Dave" seems to have lost interest in that discussion, so I am not getting any more information from him to try to fine-tune my thinking. So, I turned to some similar old data that I had to see if I could learn some more about QuickLOAD and internal ballistics.
So, it is not my load that I am "unhappy" with, and I am not "unhappy" with QuickLOAD. It is just that I think I can improve my understanding of these things with some more work. And, it would help to have the data I asked for to achieve that.
SO, does anybody have the data I asked for in the original post?
And, any ideas on how best to adjust QuickLOAD powder parameters to match a series of velocity measurements so as to best estimate the pressures (which I don't have) would also be welcomed. The manual suggests matching a series of velocity + pressure measurements TOGETHER by varying the burning rate factor and the specific heats ratio, but NOT the heat of explosion. That seems wierd to me, in my current state of advanced education in gas dynamics but lack of formal education in internal ballistics. My training says that the specific heats ratio of a mixture of gases is a physical function that is controlled by the specific heats ratios of those gases and their fractional contribution to the gas mixture. So, I don't understand how the specific heats ratio would change from one lot of nitrocellulous to another without changing the amount of nitrating, which I would expect to also change the heat of explosion. On the other hand, I can fully understand that the QuickLOAD model results can be changed by tweaking parameters, even if those tweaks don't match physical reality. So, I am wondering what tweaks are "best" for inferring pressure from velocity when there are no pressure measurements and the velocity needs tweaking to match measurements.
So, again, DATA PLEASE, and ideas, too.
SL1