I used the data on this website to develop light loads for my 1888 Trapdoor and was able to develop accurate loads. >>
http://www.gmdr.com/lever/lowveldata.htm That being said, I have experienced high pressure when loading light charges for .38 Special PPC loads for my revolvers. Every so often it sounds like a Magnum cartridge is being fired and the primers on the hot rounds are flattened.
IMHO the big concern is with bottle neck rifle cartridges. I contacted Hodgdon by telephone and spoke with a gentleman about loading light charge weights in 30-06 cartridges with IMR 4895. Hodgdon H4895 is made in such a way that you can get away with loading at 60% of the published maximum charge weight for a particular cartridge. The rep from Hodgdon cautioned me about trying to reduce charge weights below the published recommended minimum charge weights with any powder other than H4895, because I could experience a "burning excursion." While trying to develop an accurate lower recoil cartridge, I pulled bullets from Greek HXP 30-06 ammunition and reduced charge weights to 80% of what was in the cartridges. I experienced delayed ignition when firing the rounds out of my M1 Garand and on occasion it sounded like a .300 Winchester Magnum was fired.
I haven't blown a handgun or rifle to kingdom come, but I have been worried a few times while experimenting with reduced charge weights in bottle neck rifle cartridges. As a rule of thumb, I stick with published minimum recommended charge weights when loading bottle neck rifle cartridges. Light loads in straight wall cartridges is another story.
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