Swifty,for a guy who is asking for help,you seem to argue a lot.
All of this applies at the same time. You don't pick a few and leave some out.
The way you "work up" a 45 ACP load is you pick one that has already been "worked up" by those in the business who have more resources.
Bullets are manufactured to different lengths. Some 230 gr bullets are longer than others. The gun,such as a 1911,will have a maximum length the mechanics of the gun will accept. You can't use ammo that won't fit in the magazine. OK,fine. But that number has nothing to do with pressure or velocity.
For pressure,its the depth of the bullet base that determines combustion chamber volume. That will vary,bullet to bullet.
Thats why its good to look at Hornady data for that particular bullet.
It fine to look at Hogdon or Alliant data,but its only valid if its specified for that particular bullet.. You can get general ideas about 230 gr bullets,bt not down to the last .2 gr of powder you can get away with.
Yes,primers matter. Thats why loading manuals tell you which primer they are using.
The loading manuals will also tell you to not substitute components.
So yes,substituting a primer can boost pressure.
Despite testimony that some barrels are "faster" than others,that may well say that some barrels generate more pressure than others.
What makes more velocity butmore pressure,with the same bullet?
IMO,your chrono telling you that you have reached the published velocity figure is a far more reliable indication you have reached a given pressure than any voodoo reading of pressure signs.
If you use the published load specified primer,specified bullet,seated to specified length,with the specified powder in specified charge weights,in the specified brass,
You have no need to "work up" a load. Just select one,and work up tp spec'd max. Achieving spec'd max velocity is an indicator you have achieved max for your gun.
Mixd brass? Another brand of 230 gr bullet? an alternative primer?
No probem! If you read your manual,you will see it says "back off 10%"
Do that,and sneak back up to the published velocity. Or maybe a little less.
Its best to have a margin of safety to cover variables.
One of which,is your powder scales. Do you have a set of test weights? Have you calibrated your scale?
How much sense does it make to talk about backing off 0.2 of a grain from "too hot" if you don't test weight your scales?
This thread has chased around the chaos of picking and choosing the variables. You combine the variables you have overlooked ( deep seating depth,hot primer,and maybe a non calibrated scale.....
Its nuts to even discuss if you want to argue through it.
With a "correct" load,your gun will run happy. The brass won't be flung thirty feet. Your velocity will be appropriate.
If those don't happen,then hunt down "Why?" Seating too deep is a "Why" Substituting a hotter primer is a "Why"
Mixed brass? No problem! But lower your velocity expectations and back off a bit.
A box stock 1911 will run and shoot accurately with less than max loads. Thats where you can load your "mix and match" components. On the mild side.
If you want peak velocities,you have to eliminate variables. Attention to details.
What may be contrary to your beliefs,800 fps instead of 900 fps will have no effect on your testosterone levels.