How to prevent leeching of lubricant into powder?

[Naphtali]

On hot summer days, having lubricated cartridges' cast bullets with SPG, how is leeching of SPG into powder charge prevented? While I ask about leeching in cartridges, I suspect leeching would be controlled partly by the near-press fit of bullet within cartridge case.

But what about using muzzleloaders or breech-loading non-cartridge rifles such as Sharps 1859/63 rifles, whose tight fit surrounding bullet is less tight? My first thought was to use multiple vegetable wads as buffer beneath bullet. Were bullets and/or cartridges unfired for longer periods - say on a car seat where greenhouse effect from sunlight through windows yield intense heat - SPG would almost certainly begin to flow.

Solutions such as leaving bullets in a cooler or not loading cartridges until you are ready to shoot are not what I'm requesting. There is probably an obvious solution, but I'm blind to it.

[Char-Gar]

I have lived in tropical deep South Texas or the Desert Southwest where we have HOT summers and have shot cast bullets for over 50 years. I have never had a problem with lubricant getting into the powder causing problems. If your are, I would suggest the following.

1. Wipe the bases of you cast bullets before seating them. I do
2. Don't use a bullet lubricant that will run when hot. I use either my own mix of Beeswax/Vaseline (60/40) or some commercial lube like NRA 50/50.
3. I have used SPG with no problem of this kind.

I am talking smokless powder loads. If you are talking black powder I can be of no help to you.

[country gent]

I use a snig fitting wad between powder and bullet with black powder loads this wad is cut from napa rubber fiber gasket material and is around .465 in dia. and .060 thick. I drop the charge hand seat the wad and then compress to depth with a die in my press, this is just to depth needed to seat bullet to loaded overall length leaving no airspace in the case. Another trick is store your ammo bullet down in boxes this way if lube runs it runs forward to case mouth not back into powder. Wipe your bullets bases ona coarse cloth or window screen to remove any lube on bases before seating helps alot also. With case neck tension lube running is harder from the grooves but any on the base or smaeared in dies will migrate

[.22-10-45]

I always use a tight fitting veg. fibre wad between bullet base & powder..however if a grease cookie is used..a hard wad can act like a squeege and remove grease from bore. In this case, I have been using thin-1/32" wad of beeswax between powder & cookie.

[BrentD]

You could always just forego the lube altogether.

Paper patching will allow you to do that.