Chrono-induced sickness

[Bluetick Lab]

One of the first things to do is measure your fired brass and set the case volume to match.

The second thing to do, after noting the difference that makes in the calcs, is to measure it a 3rd, 4th, and 5th times, just to be sure.

I use the chrono as a proxy for the strain gauge I haven't installed yet. I have in mind a number as I shoot off the first few rounds. If real world varies much from that, I re-evaluate what might have caused it.

The other thing I had in mind as I wrote initially was 4350 seems not so optimal for the very light bullets you mention. GRT can be useful to look at other powders. A slightly faster powder, CFE-223 perhaps, might be a better match. (Not to mention that I haven't quite learned the knack of throwing consistent charges with those big logs of kernels.)

Cheers!

Yes, I was measuring case capacities even before I started using GRT. My progression of methods has been somewhat haphazard obviously, but things are starting to solidify for me.

One might think the 4350s are a bit slow burning for an 80-grain bullet, but they are right in the neighborhood of all the powders Barnes recommends. In fact most of the ones they list are higher on the burn rate chart.

https://www.barnesbullets.com/wp-content/uploads/2021/05/243-Winchester.pdf

 

[MikeWhy]

It is indeed. My head was somewhere else. I'm glad to not have been able to lead you astray.