I'm wary about using data from older manuals and publications with Unique. It doesn't take as much Unique now to generate the same velocities with the same cast semiwadcutters since I started reloading in the 70s. It's far better to start low and work up particularly with Colt Single Action Armies, SAA clones, and S&W N-frames. A chronograph helps immensely.
I looked at the Alliant data. It shows a max. of 9.5 grains for its swaged-lead semiwadcutter. It's almost straight lead with just a little antimony added, which explains the higher charge of one whole grain over Lyman data. It's far better to use Cowboy action data for those swaged bullets, or you'll be cleaning lead out of the revolver until the weekend after next.
Yes, you can push swaged lead bullets faster. But I don't like pushing Lewis Lead Removers and lead-wipe-away patches.
I'm also wary of older reloading manual data, but not so much because it takes less powder now than in the past. The loads have been reduced for many powders, not just Unique and that's an artifact of some reloading manuals getting a little more conservative - probably after having their data blow up some not so strongly constructed firearms.
For example Hornady used a Buntline Special to develop load data in its
second edition in 1973 - the first edition that had handgun data. In that edition the max loads for a 250 gr jacketed hollow point were:
Bullseye = 8.4 gr
Unique = 10.0 gr
630 = 17.1 gr
2400 = 17.7 gr
In the third edition in 1979 they used the same Buntline Special and the same JHP, but all the maximum loads reduced significantly:
Bullseye = 7.2 gr
Unique = 8.8 gr
630 = 14.5 gr
2400 = 16.4 gr
A couple other powders also appeared for the regular .45 Colt load:
700X = 6.8
296 = 21.6
And they also published Ruger & T/C only loads for the 250 gr JHP:
Unique = 11.3
Blue Dot = 15.1
630 = 16.6 - note that this is less than the 17.1 max for the buntline loads in the second edition (!)
2400 = 19.9
IMR 4227 = 22.4
Fast forward to the sixth edition in 2003, where they used a Ruger Bisley Blackhawk and look at the old powders that are still listed for the 250 gr XTP:
Bullseye = 6.5 (compared to 7.2 in 1979)
Unique = 7.4 (compared to 8.8 in 1979)
Nitro 100 = 6.8
Win 231 = 7.3
Clays Universal = 8.2
They also added a swaged lead 255 gr FP by this time as well, and it reflects the pattern of slightly lower maximum charge limits for lead bullets, set by leading issues rather than pressure concerns, and it's worth noting all the velocities are higher than the 250 gr XTP loads by 5o to 100 fps:
700x = 5.9
Nitro 100 = 6.2
Unique = 7.0
Win 231 = 7.0
Clays Universal = 7.9
The Ruger and T/C only loads for the 250 gr XTP include:
2400 = 20.8 (an increase from 19.9 in 1979)
IMR 4227 = 24.2 (an increase from 22.4 in 1979)
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What does all that mean? Maximum loads vary based on the people making the manual, the methods they use to determine maximum acceptable pressures, the firearms used, changes in the bullet designs over time (harder or softer core or jacket, slight changes in diameter and/or bearing surface, etc), and plain old lot to lot variation in the powders used in testing.
My advice is to take all load data with a grain of salt, particularly if you are substituting components, since bullets of the same weight and diameter from different manufacturers can create significantly different pressures in the bore with a given charge.
