Apparently folks view chronographs in different ways. I see one as the single best way for reloaders to stay out of trouble. Dr. Howell described handloading as akin to riding a bicycle close to the edge of the Grand Canyon at night. You can sort of know you're getting close to going over the edge but you don't really know where that edge is. A chronograph sheds much better light on where that edge might be.

Velocity and pressure are not a 1:1 correspondence but they are very closely related provided one is using a powder reasonable for the task. It is not exact in that X fps = Y psi, but if used properly with some common sense velocity readings can act as a series of warning lights to tell you that pressures are green, yellow, amber or bright red with a pretty large degree of confidence. Used in conjunction with good pressure tested data a chronograph is a better indicator of what's going on in the combustion chamber than all of the "pressure signs" ever dreamed up. Of course, if the rifle flies into a thousand pieces, that's a pretty reliable pressure sign....

Without going into a long treatise of how to use one to best advantage, I can think of two times in particular when a chrono was the only thing telling me something was definitely wrong.

1. Worked up a good load in a .270 and .300 WM with RL-22, velocities were as expected for the charge weights used - which were not absolute max. After finishing up an 8 pound keg I bought another keg from a different lot. Using the exact same charge weight velocities were 200 fps faster - about 3300 for a 130 grain bullet in the .270. I have no idea what actual pressures were except that they were "really high". I had to back off several grains with that lot of powder to get back down to a reasonable velocity for the cartridges.

2. Just recently I had a .243 AI whose accuracy was going south. I figured after 2300-2400 rounds that barrel was getting toasted. I chrono'ed a fireforming load which should have been a mild load in a standard .243 and velocities were almost 250 fps above what they should have been. Again, I have no idea what the actual psi was, just that it was way beyond a safe working maximum. A tight patch and brush down the barrel found a very tight spot indicating a major buildup of copper just ahead of the chamber. After cleaning thoroughly velocities dropped back down to normal and accuracy returned to normal as well. Without a chronograph I never would have known that pressures were slowly creeping toward a KB. Link to original thread about this


If someone wants to read a lot into SD's, maximum spreads and stuff that's fine, too. They can give you data beyond what's on the target to find an optimum powder and load, but the single biggest benefit to me is simply knowing the actual velocity in any particular rifle in relation to what should be expected and telling me with a fair degree of confidence that my load is Safe, Getting Close to Unsafe, or Whoa!

Gunnery, gunnery, gunnery.
Hit the target, all else is twaddle!