Any load that perceptably varies with a muzzle up or down positioning before firing scares me. You are obviously getting a wide swing in pressures.
Art; are you sure you mean oatmeal? Back when God and I were both young what I used was cornmeal.
The difference in velocity with the 30-06 is of a different magnitude. I recall a sargeant who used to be able to work the action in a Springfield in two different manners, both of which appeared to be the same, but would print differently on the target. There was no apprecable difference in recoil, or muzzle blast, however.
Please advise what caliber you are using, what powder, how much, and OAL of cartridges.
If, as I suspect, you are using .45 Colt, you could be in deep trouble shortly. A few years ago there was an article in one of the gun rags where a guy detonated a SAA with a load of green dot, which he had used for years, and was a safe load. The only difference was a change from 250gr. bullets to 200 gr. bullets, increasing cartridge case volume.
The damage to the gun can be distinguished if the cause is detonation, vs a double load, BTW.
The reason why many loads are excluded from loading manuals is because of non-uniformity from shot to shot.
Please advise more details, and I will see if I can help. BTW, some gun mag, either American Handgunner, or American Rifleman, had an article on Cowboy shooting and loads for same about six months ago. Walt