I've wondered what kind of load would be used for that light a spring myself. I'm using a 14# in my bullseye loads, and find it hard to believe that an effective load for 10# springs is practical. Really light loads seem to either hamper powder performance or be potentially dangerous. I'm curious to see what others have to say, too.
My experience so far has been that light loads in medium- to slower-burning powders are problematic because the powders are not designed for them. I found W231 in the range of loads you are currently using left a great deal of unburned powder that ejected out of the muzzle and down my arm. TiteGroup in light loads created an unacceptable amount of chamber fouling. I'm told that with standard loads neither of these powders has these problems. You will probably find that your light loads are in fact under the minimum recommended charge for these powders.
I'm currently using Clays (a fast powder with higher nitroglycerine content), which is remarkably clean, but needs a heavier load in relative terms (3.6-3.8 grains) than I could get with the others, because it does not meter consistently for me. It tends to regularly throw under by .2 or .3 grains. I like the powder, but if I try really light loads I will get a number of FTF because of these undercharged rounds.
Using extremely light loads in fast-burning powders can be dangerous, since the small charge will only partially fill the cartridge case. The flash from the primer could pass right across the top of the powder, ingiting all of it simultaneously. This is not how progressive powders are intended to burn and can create excessive pressures. In other words, be careful creating light loads with fast powders.
My experience so far has been that light loads in medium- to slower-burning powders are problematic because the powders are not designed for them. I found W231 in the range of loads you are currently using left a great deal of unburned powder that ejected out of the muzzle and down my arm. TiteGroup in light loads created an unacceptable amount of chamber fouling. I'm told that with standard loads neither of these powders has these problems. You will probably find that your light loads are in fact under the minimum recommended charge for these powders.
I'm currently using Clays (a fast powder with higher nitroglycerine content), which is remarkably clean, but needs a heavier load in relative terms (3.6-3.8 grains) than I could get with the others, because it does not meter consistently for me. It tends to regularly throw under by .2 or .3 grains. I like the powder, but if I try really light loads I will get a number of FTF because of these undercharged rounds.
Using extremely light loads in fast-burning powders can be dangerous, since the small charge will only partially fill the cartridge case. The flash from the primer could pass right across the top of the powder, ingiting all of it simultaneously. This is not how progressive powders are intended to burn and can create excessive pressures. In other words, be careful creating light loads with fast powders.
