I start at the bottom when I have a completely new set up. When I just change a component like Joe's 150 grain SP for Bob's 150 grain SP I will always back off, but may not go all the way back to the bottom. Depends on a lot of factors. Bad practice, but there it is.
You betcha I start low and work up when I am working with a high pressure cartridge in a new gun.Might start halfway up when I am working with a gun that has given predicted results with a couple of other loads. Might not bother to change at all when when I am just opening a new can of powder for a proven load that is a couple of grains under book max.
For a lot of stuff, the notion of working up is plain silly. We simply do not have a means to read pressures under 30k psi. The usual signs don't work at those low levels. For those, I will load any charge listed in several manual that is within the acceptable range. Any working up I do is for accuracy only.
I have seen where an identical caliber/bullet combination max load is the start load in another manual. I usually split the difference and start in the middle unless it is a caliber I am unfamiliar with or a type or brand of powder I haven't used. I will start just above minimum and load 5 or 10 rounds and fire them across the chronograph to see if the load infomation is anywhere in the ballpark, and then go from there.
For me, it depends on the cartridge. Fir example, if it was one of the new wonder rounds like the .300 WSM, there's a good chance I'd start with the ebginning load or no more that one grain above the starting load. With a cartridge that is known to not be loaded to it's full potential, I'll usually start in the middle, or maybe a grain higher than the missle load. cartridges such as the .257 Robt., 7x57 Mauser and 30-06 immediately come to mind, as they were originally chambered in weak guns.
Have you ever wondered that if a Remington 700, Winchester M70 or Ruger 77 can be chambered to a .300 magnum at 60,000 plus PSI, but the same gun in 30-06 is only loaded to about 50,000 PSI? Is the gun chambered to the 30-06 made of weaker material? I think not. So the problem becomes the lack of modern data for use in a MODERN rifle.
I certainly will not pass on data for loads I've worked up for some of the above mentioned rounds, but I will admit to getting 2880 FPS safely from a 7x57 Mauser in a Winchester m70 with 22" barrel. Nearly 2800 FPS with 180 gr. bullets in the 30-06, and 2550 FPS from 22" barrelled .35 Whelens. All these loads were worked up in late model modern rifles, strictly as an experiment and for limited use in the hunting fields. They're not for plinking or general target practice.
Do I suggest that anyone copy or use my line of thought? Not at all. I do this for my personal edification and to satisfy an innate curiosity as to the full potential of certain underloaded cartridges.
I always start with the minimum load (10% below max) and shoot a minimum of 10 out of 20 rounds through the chrony. If the results are within reasonable range of the listed performance, I go to the next load.
Why should I end this re-incarnation early by not following the guidelines?
I usually start just above the bottom, and had good success.........except when I started loading for the 357 Max. After many tries to find an accurate load, I finally tried the "min" load, and wouldn't you know.......the thing shoots great! So I gave up about 150FPS, but at least I can hit what I'm aimming at! :wink: Any new calibers I will start at the bottom!
Like some of the other reloaders here, I start just above the bottom with a modern firearm not of a weak design, if it's a new rig for me. I like finding the real potential of a caliber, then I fine tune for accuracy. I like to find two accuracy levels for each caliber. One low speed for plinking or letting my kids shoot, and one full throttle load for hunting. I usually find my full throttle performer to be .5 to 1 grain or so below the max posted in some manuals. All manuals seem to be quite different so the information in them needs to be compared and considered whole heartedly. With the pressure reading equipment that is used in developing the data, the findings can't be ignored, but I have always found that the max loadings can be exceded in most cases. Sometimes by a good bit. Careful experimentation is a must though. I do not reccomend anyone doing this. I do it for my own satisfaction of finding out what my firearm will do and how the speed affects the accuracy and the cases, primers, and so forth.