I have used Blue dot in the 45 ACP for decades.
Cannot speak to the 40S&W but I have used Blue Dot for 357, 44Mag, 45 Colt, 45 ACP, 454, and 475 with results ranging from okay to excellent.
The thing I came to understand about it was that if its burning "dirty" you're probably not using enough powder.
This seems to be true of any powder when you don't give it enough work to do. (Unique comes to mind.)
I got "dirty" performance too until I started using it like a magnum powder...which is what it is.
I'll call it the "entry level" to magnum powders.
If you want "normal" performance use powder made for that level.
Blue Dot is a very good powder but its even better when loaded so it isn't burning "dirty".
For a long time I used 10.0gr Blue Dot behind a 230gr JHP of any Mfr.
A potent full-power load with generally excellent performance.
My range notes while doing some experiments with this ctg & powder and some "high performance" JHPs says the following:
Guns used this day: Blackhawk w/ 5.5" barrel, H&K USP w/ Jarvis 6" ported barrel, GI-Spec Model 1911 (built from parts.)
Load 1:
45 ACP
230gr Hornady XTP
Blue Dot: 11.5gr
Primer CCI 350 (Mag primer)
OAL:1.69"
Load 2:
Same as load 1 but with the 230gr Remington Golden Saber and
OAL: 1.260"
Mixed cases were used for each load.
Velocities:
Blackhawk w/XTP:1105, 1156, 1126, 1132, 1133, 1103 = avg: 1125+fps
w/Golden Saber: 1119, 1124, 1094, 1132, 1103, 1152 = avg: 1120+fps
H&K USP w/XTP:1141, 1143, 1131 = avg: 1138+fps
w/Golden Saber:1094, 1102, 1039 = avg: 1078+fps
Mod. 1911 w/XTP: 1103, 1090, 1043 = avg: 1098+fps
w/ Golden Saber: 1003, 1085, 1062 = avg:1050+fps
I think this is about as far as the 45 ACP should be taken with 230gr bullets.
This is the approximate performance of the 45 Super cartridge which is simply a 45 ACP loaded to the maximum SAAMI Specs, (with other subtle difference.)
It should be noted that accuracy was only "fair" in the semi autos.
The Blackhawk likes whatever I try with the 45 ACP cartridge.
Also, it should be kept in mind that no cases showed ANY signs of high pressure, (and they seldom do.) SAAMI Specs are much higher pressure than what the industry considers "normal" for this cartridge.
I have been pushing things with the 45 ACP for years and have decided the real reason why "standard" loading is always so far below SAAMI Specs (compared to what the cartridge can clearly do,) is that accuracy in semi-auto pistols tends to fall off rapidly when velocity goes much past 900fps with 230gr bullets. That has been my observation with dozens of chronographed groups over the years.
The lighter weight bullets will normally go faster before accuracy begins to fall off. No surprise there I guess.
As a secondary observation I can say that all semi-autos I've ever used or seen fired with hotter ammo ALWAYS functioned better (more reliably) than with "standard" or target-powered loads.
That GI-Spec 1911 tells the tale well.
Once 900fps is reached it never fails to function, (feed and fire.)
BTW, the 45 ACP really shines when a 250gr bullet is used at around 800fps.
That is becoming my Pet Load for that ctg.