I use a very old factory recipe that was originally intended for outside lubricated bullets such as .22 rimfires and the .32, .38 and .41 Long Colt.
I use it in all black powder applications, and have also used it in my .357 Magnum at velocities up to about 1,200 feet per second.
Perhaps it works at higher velocities, but I haven't tried it with smokeless powder at higher velocities.
The recipe is:
1 part paraffin (I use canning paraffin, sold in grocery stores)
1 part mutton tallow (sold by Dixie Gun Works. Regular lard will work but not quite as well).
1/2 part beeswax
All measurements are by weight, not volume.
I use a kitchen scale to measure 200/200/100 grams of ingredients.
Place them in a quart Mason jar. Place the jar in 3 or 4 inches of boiling water. Ensure all ingredients are thoroughly melted, then stir with a clean stick or disposable chopstick.
Allow to harden at room temperature; hastening cooling by placing in the refrigerator may cause the ingredients to separate.
When cool, screw the lid down tight and store in a cool, dry place.
To use in a lubricator/sizer, thoroughly clean the sizer of all traces of the older lubricant. A can of brake cleaner will dissolve all of the old lubricant. This is best done outdoors onto newspapers, of course.
When clean, place the jar back into the boiling water and pour it into the reservoir.
You can also pan-lube bullets, which does not size them to diameter. Simply place the bullets base down in a pie pan, melt the lubricant in boiling water again, and pour the lubricant in the pan until it fills the top grease grooves.. Allow to harden then remove the cookie of grease with bullets still enclosed.
Simply push the bullets from the nose, out through the back of the lubricant cake.
The above lubricant is nearly identical to SPG. At the range, others have thought I'm using SPG. The greatest difference is the scent. It's slightly stronger with SPG.
Some may pooh-pooh the use of paraffin in the recipe because it's a petroleum product. Genereally speaking, petroleum products when mixed with black powder create a hard, tar-like fouling.
However, this hasn't been the case when I've used canning paraffin. A chemist in another site said that paraffin lacks the hydrocarbons found in other petroleum products. Apparently, hydrocarbons are the culprit.
I don't know about any of this, but I DO know that paraffin, when used in the above recipe, doesn't create any of the troublesome fouling that other petroleum products create.
This is a very good lubricant. For black powder and low-velocity smokeless powder loads. It's all I use.
As to lead alloy:
If you use black powder, you must use a very soft alloy. Certainly no harder than wheelweights (about 9.5 Brinnell Hardness). Pure lead is about 4 BHN.
Black powder demands soft lead bullets with a soft non-petroleum (non-Alox) lubricant for best accuracy and to prevent leading.
A hard-cast lead bullet with petroleum lubricant, when used with black powder, will be inaccurate and cause a great deal of leading.
This is why some shooters get discouraged when they load black powder in their .45 Colt, .44-40 or .45-70. They buy hard-cast bullets, with a hard lubricant intended for smokeless powders, then load them on top of black powder.
Accuracy is dismal, leading and fouling are terrible. Yet, such bullets work fine with smokeless powder. So the reloader thinks that black powder is worthless.
Actually, black powder is very consistent when measured because so much is required.
If you are off by half a grain of weight with smokeless powder, it can cause velocity variations. But a half grain of black powder variation, because so much black powder is required, won't make a whit of difference.
With the proper lead alloy, and the proper lubricant, black powder loads can be remarkably accurate.
One more thing: any type of copper fouling in a bore is pure poison to lead bullets, whether they are propelled with smokeless or black powder. You must have a bore scrupulously clean of copper and plastic fouling if you use lead bullets.
If 777 says that smokeless powder lubricant is fine then it must be. Trust the manufacturer over me. I've never used 777 so I can't speak from experience with that propellant. However, I think the above lubricant will meet all your needs.