For the life of me, I can't get Universal to burn completely in any cartridge I load it in, even near-max loadings for .44 Mag.
That is a little surprising considering Universal was originally developed as a heavy load 12 ga. powder where pressures don't even reach that of the Specials.
I am afraid I don't have many suggestions for you except to report what I do.
One of my recent favorite 44 special loads is 6.5 grains Universal under a Rainier 240 PFP, COAL=1.475", CCI 300, taper crimp.
This bullet has no cannelure so a roll crimp is not possible.
Very accurate in the 696-1.
There is a very small amount of residue in the barrel but it is not powder.
Nothing comes back out of the brass to gum up the gun.
A similar load I use (I call it my Euro load) is 6.5 grains CSB-1 under a Rainier 240 PHP, COAL 1.5", Ginex P1 primer, Speer 44 special brass.
Again with the taper crimp.
I get 840 accurate fps out of the 696-0.
Absolutely no residue with that one.
For a rural carry/hunting load in the 44 special I use 8.5 grains Universal with a Sierra 210 JHC profile (roll) crimped in the cannelure.
Again with the CCI 300 using Starline nickel plated brass.
This load is almost assuredly over the 15kpsi mark and into that 20-25kpsi region Brian Pearce wrote about.
I won't shoot it in a Bulldog or 396 but all my steel S&W 44's will take an occasional test group.
I get 1055 fps out of a 696.
Sierra says I should get some expansion at this velocity.
Never had the opportunity to test that.
I am now experimenting with N105 to try for that kind of performance with a little lower pressure.
Why?
Because I like carrying this gun more than my larger magnums and don't feel the need for that level of energy around here.
Also because I have some N105 I got when 2400 disappeared during the shortage.