In my experience, many hand loaders underestimate the importance of a faster powder in a short barrel, especially in a magnum cartridge where's a lot of powder to be burnt in the available bore.
I don't have any .44 Mag or .45 Colt chronograph data handy at the moment, but I pulled some chronograph data from recent load development for 125 gr XTP loads using Win 296 and Unique in a 3" Ruger SP101. The results are pretty significant. In both cases, I started mid range, and stopped when the cases started to stick slightly on ejection.
Win 296
18.0 gr Win 296
Average velocity = 1090 fps
Standard Deviation = 45.77 fps
19.0 gr Win 296
Average velocity = 1116 fps
Standard Deviation = 56.85 fps
19.5 gr Win 296
Average velocity = 1132 fps
Standard Deviation = 35.49 fps
These are loads I rejected due to:
a) the high SD,
b) the relatively small increase in velocity for the increase in charge weight,
c) the very large and visible muzzle flash even in the mid day sun; and
d) the large amount of powder being blown back at me.
All of the above are indicators that the load just isn't very efficient in the 3" barrel, which makes sense given that Win 296 is a slower burning powder
Unique
In comparison here are some loads using Unique with the same bullet in the same 3" SP101:
8.0 gr Unique
Average velocity = 1169 fps
Standard Deviation = 29.81 fps
8.5 gr Unique
Average velocity = 1243 fps
Standard Deviation = 31.65 fps
9.0 gr Unique
Average velocity = 1296 fps
Standard Deviation = 27.69 fps
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The 8.2 gr and 9.0 gr Unique loads compare to average velocities of 1250 fps and 1340 fps respectively in an 8" revolver, so with a faster burning powder like Unique, the loads are actually losing very little velocity despite a barrel that is 5" shorter. There was also significantly less muzzle flash and no residue being thrown back at me.
In contrast, the 18.5 and 19.0 gr Win 296 loads generate velocities of 1390 fps and 1440 fps respectively in an 8" revolver. That's a velocity loss of just over 300 fps in the 3" barrel.
The high end load with Unique is also 164 fps faster than the top load with Win 296 and it's clearly a better performer with similar peak pressures, judging by the ejection of the brass. Even in mixed head stamp brass, the SD is significantly lower and with charge weights roughly half as much as with 296 the recoil of the two loads is comparable despite the higher velocity of the Unique load. Plus, with half the weight of powder being burnt, the powder cost per round is half as much.
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Personally, for calibers like the .357 Mag, .44 Mag and .45 Colt I normally limit my use of slow burning powders like Lil'Gun and Win 296 to Contender and carbine length barrels and the shortest I go is a 7 1/2 Blackhawk with the powders, and even in a 7 1/2" barrel it's not completely efficient.
The payoff for an efficient and consistent burning load is also usually better accuracy, especially if you find a sweet spot for the barrel.
This is very good accuracy from a 3" snub at 10 yards:
Even the 10 shot group looks very good, especially when you consider the flier was my fault with a bit to much pressure on the trigger before the sights were precisely aligned.
.44 Magnum 200 and 240 grain loads:
The sad fact of most major reloading manuals is that they tend to use newer powders in newer editions and a lot of very good loads using older powders get left in the dust.
If you can find an older loading manual on e-bay, it's usually worth the cost, especially with pistol powder availability being a little spotty, making some powders hard to find.
The Hornady Second edition lists both Bullseye and Unique for the .44 Magnum with 200 gr and 240 gr hollow points using a 7 1/2" barrel, but as noted above, you shouldn't be losing much velocity in a short barrel.
Take the data with a grain of salt and work up slowly as you'll be substituting a different bullet with different bearing surface and "stickiness" in the bore.
200 grain hollow point:
Bullseye:
starting load:
9.4 grains (1150 fps)
Maximum load:
11.2 grains (1300 fps)
Unique:
starting load:
10.6 grains (1150 fps)
Maximum load:
13.7 grains (1400 fps)
240 gr hollow point:
Unique:
starting load:
9.7 grains (1050 fps)
Maximum load:
11.2 grains (1200 fps)
