Caveat: my comments are based on 'general knowledge' about load development, NOT on specific knowledge with this forumula and its variants.
As you approach maximum loads, your chronograph readings will probably show wider ESs--that is, Extreme Spreads--and a notable variance, up or down in the delta that exists between recipe variations. That is, whereas earlier in the charge weights a one-tenth grain increment resulted in a fifteen fps increase, at the pressure limit it 'suddenly' results in no change, or 25 fps--that sort of change. If this happens, back off. Period. Back up at least two-tenths, or 5%, and regroup.
Then try tweaking other variables--a minor change in crimp, possibly a change in LOA, a different primer--that sort of variation. Lee's reloading has a good discussion of this, even though its based in rifle cartridges and pressures. It's early in the book; look it up at read it.
Luggernut has it about right--you should have no trouble reaching major within pressure specs. But, successful reloading suggests you are sure you have the fundamentals down first.
Given the fact that you are new to reloading, I would suggest that prior to jumping in on this project, you learn to do development load techniques that will teach you how to build consistent ammo.
Focus on building some lower / medium range rounds that will find the sweet spot for accuracy with your particular firearm. Chrono the rounds; do the tweaks that get you low SDs, and look for the correlations that give you good accuracy first.
Personally, I would start with NEW brass, but at the minimum it should be brass that, if used, is sorted by headstamp and, arguably, trimmed to the same length.
I do this with pistol calibers by first selecting the general recipe I want to use and starting with the minimum charge. Once I am sure I have the dies set up for proper physical assembly--for .45ACP, that would be the proper LOA for good feeding, and the proper (taper) crimp, then I
1. Load 20-round batches of the minimum level, then
2. increase the charge weight by two-tenths grain, and
3. load another twenty rounds, and
4. repeat as needed until I stop about two-tenths below the manual's max charge.
Try using the ammo this way--after testing your general skills by shooting some "extra" rounds you've built:
1. Fire 5 rounds 'normally' and concentrate on noting feed, ejection, and your own (subjective) interpretation of recoil.
2. Fire a second 5 rounds to look for accuracy--i.e., from a benchrest (IMO).
3. Compare this to your own recall of factory ammo loads you've shot, and write this information down.
4. Now fire five shots for chrono readings. If you see inconsistent results, fire a second string of five rounds to confirm (or not confirm) the kind of data set you are getting.
Jim H.
