Originally Posted by uncleB
So if a person wants to precisly measure what goes INTO a case, why would that person not want to precisly measure what comes OUT ????
It just does not make sense.
I'll give two bits to the person who can tell me who it was that said, "the two most important tools to the rifle shooter to ever come along are the chronograph and the borescope".
Let's examine why this person would say this. Until the invention of smaller, cheaper, personalized chronos were made available, the reloader could only "paper tune" like what this Steve Shelp does. This works-to a degree. But the chronograph speeds up (no pun intended) the load development process by a factor of 10. Leaving the chronograph out of 90% of the development process and using it for the remaining 10% is backwards and I will tell you why. CHrono's tell you much more than the speed of your load. They also show you pressure curves, load nodes, minimum and maximum sweet spots, maximum pressures, minimum pressures, average velocities, load uniformities, effects of neck tension, effects of bullet seating depths, effects of new lots of powder in conjunction with burn rates, effects of different primers, bullet jacket differences, and so on. Shocking isn't it?
For the "paper puncher" who knows exactly how far his target is and gets basically limitless sighter shots to adjust, even knowing the most basic thing as average velocity is meaningless. But to the long range hunter (which is what this site is all about) he needs to know how fast his ammo is to formulate a correct drop chart. That right there all by itself warrants a need for a chrono. I usually take TWO chronos to the range to get an idea of what the bc of a bullet is out of that particular gun (as they are all slightly different) and I very rarely shoot at 100 yards WITHOUT a chrono. About the only time I do is when I am practicing for short range comp with my 6ppc. But I still chrono it when developing a load because I have found that loads with better sd's stay more accurate over a wide variety of conditions than loads that don't. But as Steve says, the group on the paper is all that matters. But what I'm saying is that even with a 6ppc, a chrono sheds light on things that PAPER SIMPLY CANNOT AND WILL NOT EVER TELL YOU! And things get even more amplified at distance.
I have probably made more factory rifles legitimate 1000 yard shooters than any 20 benchrest shooters have medals in their trophy room and that process would not be possible without a chronograph. Period. Show me one custom gun that was paper tuned and was accurate and I'll show you a dozen sub par guns that were made 1k accurate with the help of a chronograph. My point is that it is much easier to make a custom gun shoot at 1k by paper tuning than it is to make a sub par factory gun shoot 1k without a chrono.
But I do agree with this Steve fellow on one account. Not all chronos are created equal. Perhaps if he had bought a decent chrono that actually was accurate, it wouldn't have skewed his perception of them. A 2' space inbetween two skyscreens is mathematically inferior by design. But, get three skyscreens spaced on a 4' or 8' rod a proof channel and the accuracy of the readout is improved. This is of course the Oehler 35 and that is why most component manfucturers use it. That is also why the military uses it and why a civilian can no longer buy one (at least through 2010).
Another point while I'm at it:
The quickest way to change the standard deviation in a load is to change the charge weight. Throwing a new primer in the mix to get a different sd can be done but is a bigger pain than just going up .5 grains in weight.
OK, another point. This one goes out to the Yaw of repose unbeliever:
YOU ARE WRONG! There has been literally thousands of test and studies done on this point and they all have documented it quite well. Just because you have failed to do research on it doesn't mean the reasearch doesn't exist!
EVERY BULLET OUT OF EVERY GUN YAWS WHEN IT SLAMS INTO THE ATMOSPHERE! SHort ones, long ones, arrows, everything yaws unless it is shot in a vaccuum. If you grasp this concept, you will quickly see that if the target is close enough, every bullet will show inaccuracies due to yaw. Some just dampen the yaw quicker than others and if the target is past where it dampens, all looks and shoots well. But don't think that another bullet has dampened at that same distance particularly if it is a longer bullet. It will take the longer bullet more distance to dampen therefor giving better accuracy at longer range.
IF the dampening of the yaw of repose didn't exist, every bullet out of every gun would go through a paper target off point because every bullet has initial yaw. DOn't believe me? Pick up a copy of RInker's "Understanding firearm ballistics" and flip to the whole chapter that covers this. Or go to youtube and watch slow motion photography of a 30" arrow yawing so bad that it looks like it is going to fly into the floor and break in half until it gets about 10 yards away from the bow and suddenly flattens out and flies straight.
I think where a lot of these non-believers get ruffled about this subject comes from a misunderstanding of terminology. When we say the long bullets shoot better at distance, we are saying they shoot SMALLER MOA, NOT SMALLER GROUPS. Or in other words, a gun that shoots 1" at 100 yards can shoot half MOA at 300 yards. That would of course be a group of around 1.5" so you can see the group didn't actually get smaller, it just shot better MOA downrange because the bullet finally stabilized and followed it's nose.
Anyhow, I have deviated from the sd question a bit but I hope this makes things clearer. Striving for a better SD is not just a good idea, it is paramount to consistent long range success. Whether you choose to find it by paper tuning or by using a chrono is totally up to the shooter but I guarantee you that one is faster (again, no pun intended) and gives you much more detail.