It has always seemed to me that the level of precision in most annealing is akin to the level of precision in weather forecasting.
Absolutely true. Most don't bother to see there's easy enough ways to achieve a level of precision.
This from the "precision shooter" who believes ANY compression of the powder charge detracts from precision....
That's on the ragged edge of putting words in my mouth, but whatever "gun writer".
~ Possibly bending a seating stem.
~ Inducing more runout.
~ Bullets creeping forward and changing seating depth.
~ Crunching the size, shape, or coating integrity of powder kernels and changing the engineered burn rate.
All good good GOOD stuff, just hold three inches left!!!
I have $70 in my DIY annealer and zero cooked fingers there Wax Candle Man.
Okay, then I WILL put your own words here, from the H414 thread on the rifle reloading forum:
"Compressed loads. I never advocate for them. Mainly because I don't like crunching kernels and potentially (and unpredictably) changing the burn characteristics of the powder. There are plenty enough powder choices out there to achieve an 85% to 100% load density without compressing a load. If that's something that doesn't bother you then who am I to argue. I won't do it though, and that's all there is to it."
And here's my response there:
"In reality some powder compression tends to improve consistent burning, and also improves temperature-resistance--even in powders designed to be temperature-resistant. I know this partly by experimentation, but also plenty of information gleaned from powder manufacturers, distributors, and bullet/ammo companies, all of which had electronic pressure labs which I visited.
"One of the most informative guys in the business was Rob Reiber, who was in charge the pressure testing at Hodgdon for decades before retiring a few years ago. He was a wealth of information on powder, including info on how to load to make it burn more consistently.
"But there have been many others as well--including the owner of one powder distributing company (since purchased by Hodgdon) who helped me run tests in their piezo lab for article information. (As an example, one session involved seeing how accurate various "pressure signs" were in estimating safe pressures. Turned out most weren't of much use.) After several such sessions he even offered me a job in the lab, but I was already making more writing than he could offer."
I will add (which I pointed out elsewhere) that it's my job to report to readers on various aspects of handloading. Which is why I tried the candle method after Fred Barker's article appeared in
Precision Shooting.
It's not the only method I've used, by far. At the other extreme I also had an AMP machine for a while, back when I was averaging shooting around 8000 rounds a year.
Here's an example of how candle-annealing can work, when shooting my 6mm PPC benchrest rifle:
And that load is also slightly compressed. I have never encountered any of the stuff you list as side-effects from moderately compressed loads--but have from "crunched" power charges. There's a lot of room between compressed and crunched.
Don't now if you're a hunter or not, but some of the most widely-used hunting handloads use compressed powder charges with no problems. Probably the best known is one developed by a gun writer named Jack O'Connor: 60-62 grains of H4831 with a 130-grain bullet. This is still a very good one, 3/4 of a century later, whether using the original military-surplus H4831 or the present "long cut" version made in Australia.