[Unclenick]

Watching for a published maximum velocity only works in theory if your barrel length is the same as the one the test data was taken with. So be sure you know the barrel length difference compensation for the bullet and powder you are using. But aside from that, for a given powder, if your gun's chamber and cartridge case dimensions are bigger than the test firearm's were, you will get to the same velocity at lower pressure than the test gun did. If they are smaller, you will get there at higher pressure.

That's why chronograph instructions almost always include a warning that you should not rely on them for determining powder charges by matching published load velocities. You see a lot of tales of false triggering and lighting and other issues that can affect the instrument's accuracy. So use the chronograph as another source of information input, but simply subbing it for keeping an eye out for pressure signs isn't safe. Pressure signs show up at different pressures in different guns or with different components. There's no reading an absolute pressure from them, nor guaranteeing you'll get to a published velocity before they show up.

Where the chronograph is maybe more useful is in checking your replication of another load you chronographed on the same machine under the same conditions, or in checking consistency of your loads. You might use it in a side by side with samples of your last loaded round to help you work up a new one using a new lot of primers, brass, bullets, or powder. But still keep an eye out for pressure signs.