Ha.....so I haven't totally lost my powers of recall. That's what I said in my first post. 4895, thank you for confirming that.
This is what I have read. Smokeless powder does not react the same as BP.I am most likely wrong but I thought the low powder detonation from a created air pocket only applied to BP. I was always told make sure you ram that Ball/bullet down tight you don't want a detonation. My concern to was a squib load going to low on powder.
During the 60s and 70s a lot of research was done using " Flash Over " ammo . It sounded like a good idea however the results were no better or worse than normal ammo and was more difficult to make and ended up being rather expensive.The subject of 'reduced loads' is interesting. One thing I've heard of in the past is a thing called "Flash Over". That is where a small charge in the case allows the primer flash to ignite the propellant in the forward part of the case rather than igniting the powder and the instead of ignition moving forward - it moves to the rear. Maybe this is a 'wive's tale', but I understand this to increase pressure in the chamber.
I just play it safe and regard "miniumum/starting load" as just that. I never exceed "maximum load/charge" - but I know that sometimes people get away with doing it. I don't tempt fate.
Prime example of those whose research into and experience with fillers who make blanket statements, is decidedly, if not completely lacking. There's a significant amount of pressure tested data on the use of fillers today. For 40+ years me and probably a million others have been using fillers and have never "ringed" a barrel and, fillers have been in use for significantly over 100 years. If done correctly the odds of ringing a barrel are probably about the same as me winning the lottery. Screw it up and you'll probably ring a barrel. Screw up a handload and you can end up with shrapnel in your carcass.....or worse. Safest thing is to know what you're doing in the first place....and that knowledge didn't come off some you tube channel by some self proclaimed expert.Lots of folks used to use fillers. Lots of folks also found "rings" in their barrels after shooting such loads. May not happen first time, but sooner or later, it seems to happen to many.
This also goes back to the use of light loads of slow powders and long rifle cases.
All you have to do is move to faster powders as you lower the charge/pressure level.
So, if you like the idea of a filler, without any testing to find if it improves anything, and don't mind replacing the barrel of your rifle, go right ahead.
Safe thing is simply to raise the muzzle in the air so the powder shifts back to the primer, lower rifle and fire.
Sorry for posting a bit off topic but it did occur in artillery shells, My Uncle Ernie was a Major in the Marine Corps and he had a fairly large casing from an artillery round by his front door he used for an umbrella holder, the primer used a tube nearly as long as the case that had holes in it near it's top.I want to remember that at one time some artillery shells actually used the concept but, artillery is a pretty big step out of my wheelhouse and I don't know if it actually occurred.
I down loaded some 7mm Rem mag years ago to blow out some dented shoulders. Couple grans below max and boy did they recoil! It was explained to me there wasn't enough powder in the case and the primer flash jumped the powder and burned from the front back. I don't know if that's right or not but It was many years before I tried case's not pretty well full again. Once I started shooting case bullet's in a rifle I think I figured out how to avoid that. In my 308 I use a very small chg of Red Dot and on top of the powder I stuff a quarter sheet of toilet paper. Works just fine. I would think if I was told the right reason for heavy recoil in that old 7mm mag, the same thing would stop the problem. Back then I was told not to point the rifle down with a round in it. In fact best to point it up in the air and bring it down slowly to shoot. Was told that will keep the powder up to the flash hole and the flash can't jump the powder!How is the minimum load figured for a round being developed ? Why I am asking this you might be wondering ? When testing loads for my 1891 Mauser in 7mm in IMR4895 I started shooting from highest to lowest 38.0gr to 34.0gr . Normally I start lowest to highest . And as normal the lowest one was the most accurate . And when shooting from 38.0 down the accuracy of course was getting better and better . The grouping at 34.0gr is very nice but still some room for improvement . Yes I know my quirks while shooting and the rifle itself factors in . As long as there is enough of a charge to get the bullet down range what or are there any dangers to loading below the suggested minimum load because I would like to try 33gr to maybe 30gr test loads to see if the accuracy would still improve more .