This talk about preference between brands is making me chuckle. Albeit, I participated and have preferences. But, I remember in the mid-70s bp became near impossible to purchase. The serious target shooters greatly bemoaned the unavailability of DuPont. I had an ml gunshop at the time and was able to purchase two 50 lb. kegs of bp, one 3Fg, the other 2Fg. I have no idea who the manufacturer was except the kegs said "Made in Scotland". I repackaged into 1 lb. boxes and sold. It worked just fine.
Maybe Curtis & Harvey? They were said to have made very good powder in their time. I think they were based in Scotland, but my memory is frequently faulty.
I got really low on powder some time around 2002 or thereabouts. It was hard to find. A club member had somewhere purchased two cases of Elephant, one case of FFg and one of FFFg, which he was sharing with club members at cost. I bought a pound of each, in the steel cans. I don't remember what I paid for it. Anyway, I was aware of Elephant's legendary dirtiness, and I was able to find some Goex before tapping into the Elephant. The upshot is that I still have two pounds of Elephant, as a "reserve stash" or "last resort," depending on how you look at it. However, I wouldn't hesitate to shoot it if it was all I had. I would try to learn how to accommodate its quirks. I don't think I would waste it. Powder is too valuable.
Regarding the OP's ignition problems, a duplex load, consisting of a few grains of better powder under the Elephant sounds like a good idea. If you have a dry sunny day with low humidity, putting the container out with the lid off to evaporate moisture sounds like a good idea, too. In early times, military installations stored bulk powder in "magazines," or secure, designated storerooms. Over time, the powder could and did absorb some atmospheric moisture. Personnel were detailed periodically to take the powder out for "sunning," spreading it out in the sunshine to dry.
I would be reluctant to enlarge the flash hole in the nipple. You don't want it so big that powder will get up into the nipple... You would get a "fuse effect" and more or less of a hangfire, and likely hammer blowback. Squint (
@Howard Pippin ) provided some good flash hole dimensional parameters if you want to try it.
I wouldn't throw that Elephant powder away, though. It has its faults, but plenty of people have made it work.
Best regards,
Notchy Bob