Starting charges and pressure

For rifle in usually start 2 grains below max so I’ve never used book minimums. Usually end a grain or so above book mins, wherever the accuracy takes me.

But for pistol I’ve started at minimums and never seen pressure signs. But it’s a small sample size.

I've experienced cratered primers and sticky extraction, in revolvers, with starting loads and factory loads. That was due entirely to rough chambers and lousy tolerances, and had essentially nothing to do with pressures. By the same token, I regularly use loads which are significantly over SAAMI pressures, in guns which are intended to handle such things - and of course which show no pressure signs.

All of which has caused me to think of "pressure signs" as nearly useless. At this point I believe it is important to know your gun - and research it, if it is as at all outside of the mainstream - and then load for it as appropriate.

While not exactly START data pressure signs Hodgdons enduron data has been "hot" in a number of different guns, with a number of different powders.
Nothing dangerous at start, but flat, flat primers, ejector marks, and heavy bolt lift happening at max or just under.

I cannot remember having any over pressure problems at book minimum powder charges but I have had erratic behavior of the charges at minimums.

If possible, I like to consult several sources of data before electing a starting level powder charge. It is not always possible with a new powder though.

History- When Barnes all copper bullets were born, there were high pressures recorded when using lead core bullet starting load data. Barnes had no data. Add in the smaller then normal groove diameters of some brands of early 7mm Remington magnum rifles & high pressure resulted.

OLD Speer #8 manual is know to produce over pressure loads.

Online, brass brands can cause a starting load to be over pressure.

The new high pressure cartridges running at close to 65,000 PSI worry me. Changing 1 component in the published data may induce high pressure at starting loads?

So far, I have avoided accidental overloads.

I can say that I have never experienced high pressures with book starting data. In 40+ years of reloading I have never found a "mistake" in published load data for any of the cartridges I reload. I have a couple guns with "tight" chambers, those running near SAAMI minimum but that is just two out of 19, with 11 being handguns and those two did not exhibit "over pressure" signs.

I think a some of the "yes" answers are from appearance of fired brass, which often is misleading and confuses newer reloaders with "pressure signs" like "flattened" primers or stiffer extraction. When I started looking hard for pressure signs I started measuring the case head for any expansion...

Loading pistol and rifle calibers - 9mm, 45 Auto and Colt, 357 Mag, 38 Spec +P, 223/5.56, 243 Rem, 25-06 Rem, 7.62x54R, 338-06. The only issue was on some start loads the rifle cases did not fully form and the primers were backed out some. Upping pressure helped. I do use a chrono and primers can show flattened, some well below max book load but the chrono still showed representative velocity according to book values. I don't push 9mm too hard due to some barrels with less case support. I don't go over book load max so really didn't get to 'pressure signs over max' on the survey.

One strange incident happened with a 243 Win in a 22-inch barrel - got 200fps above book velocity with 100 grains using near max Hornady data. Temps were 70 degrees so not hot out or heated by the sun. Brass had no pressure signs and easy extraction, case head expansion was nil. This was one barrel in one rifle and was the only time that happened. Hear of 'fast' barrels - hmmm, maybe 100fps variation but this was strange. Usually see less fps in the real world and chrono than the book data.

You need another category. I found H110 at min loads in 44mag has all the appearances of being higher pressure than closer to max loads. Not sure why that is, but I switched to 2400 and found that powder to be much more linear and tunable in 44mag.

H110 seems a special case.
Hodgdon used to say not to reduce loads more than 3%.
Winchester, back when they were selling their own powder, said to load 296 only as shown, no reduction, no other components.
Current data shows a one grain - 4% - reduction to start.

Otherwise, I don't recall any MINIMUM loads. Most book STARTING loads are about 90% of maximum... except Lyman.

As far as unanticipated "pressure signs" I have cratered Federal primers with a below maximum 9mm P load. Return to Winchester primers resumed normal appearance.
And do bullets distorting or coming apart from too high velocity for a fast rifling twist count? I've done that.

I have only experience pressure signs once when loading within the specified range. I am pretty sure that was an error on my part. I rarely load at the minimum any more. I have never found it to be productive.

In my case, it was sort of the first vote.

I was relatively new to reloading, and I got overpressure signs in .308 with 150 grain bullets. I was not using exactly the same components as in the book. The powder was in the fast range of the powders listed. I'm not sure exactly what caused it, but I suspect my bullet was seated significantly deeper than the bullet tested in the data. I did not work down, rather stopped the combination of this bullet and this powder entirely and used a different recipe specific to the bullet.

That can of powder sat on my shelf for many years before I dared to use it in an entirely different caliber, and did so without incident.

Mine was my 270win MGM Encore barrel. The start load of H4831 flattens primers and sticks the brass in the chamber. I sent the barrel back to have checked, and they said the leade was short, so they corrected it. It still does the same unless I use nickel brass. This is the same with 130 or 140 grain bullets, and IMR 4350 as well.

In bolt guns I'm normally right at where pressure starts to be a issue I find that's where they tend to shoot.