My own experimentation has been limited to high-pressure rifle calibers, mainly with WC860 in the 7.62x54R. Even with heavy bullets and mag primers, it was impossible to avoid unburned powder in the barrel and hearing a good bit peppering the ground in front of the muzzle. What has been said about using a faster propellant as an initiator to increase pressure and temperature to get the slow stuff lit is spot-on. Also, the warning about lot-to-lot variation is correct. You'll want to check your results with a new lot, as you may need to fine-tune your load. My goal with the 7.62x54R was to get a clean, powder-free barrel and a POI/velocity the same as surplus ammo with bullets of the same weight. The initiator I used was 4759, but 4198, 5744, Reloader 7 and similar fast rifle powders will work well. It's just a matter of putting in a few grains of your chosen fast powder and filling the case with 872 so you get a compressed load. If your barrel has a lot of unburned powder in it, increase the amount of fast by a grain or less and try again. Eventually you'll get to where the amount of unburned powder in the barrel has all but disappeared, your velocities and POI are coming up and it's pretty much done. The purpose of always using a compressed load is, much as possible, to keep the powders from mixing, hence, "diluting" the ignition of the faster powder and causing inconsistent results. Extruded powders of large grain, like 5744 seem to stay put better than, say, a ball powder which is easily scattered. the experience of shooting these is that they are milder and lower in recoil than the surplus I was shooting at the time. Primers were rounded and showed no signs of excessive pressure.
Again, this is for high pressure rounds out of a strong action. I have no experience using this powder in BP rounds in weaker actions.