45 Cowboy Special (or sometimes just 45 Special) is a 45 ACP case, with a 45 Colt rim. The 45 Colt rim is smaller than the rim on a 45 Auto Rim. This lets it feed in many cowboy-action guns and use common 45 ACP load data. The smaller case-capacity means better performance with light loads, which is why I am interested in it.
I found a source for factory “American Cowboy Ammo” .45 Special. Specifications: “180 Grain Round Nose Flat Point” at 475 feet per second. I disassembled a loaded round and the bullet weighed 183.5 grains actual, over 4.4 grains of mystery powder. Unfortunately the factory rounds would not reliably chamber in my Ruger Blackhawk 45 ACP cylinder. I believe they were hanging up on the bullet nose. Only about half would fit in an EGW chamber gauge. Rounds that fit would not always chamber. Everything chambered fine in a 45 Colt cylinder.
Firing Record on 3/7/2017 at Sunnyvale Rod & Gun ~ 55℉ outside
Firearm 5.5″ Ruger Blackhawk with a 45 Colt cylinder
LabRadar Series: 68
Velocity: 485fps avg (555,513,526,472,576,347,450,435,488)
Spread: 576 – 347 = 229fps
Std Dev: 69.45 fps (9 shots)
Approximate Drag Coefficient: -0.64 fps/yard
Notes: Very light recoil, very quiet report, but significant unburned powder. Power Factor ~90 or only double the recoil of a .22lr.
After firing the factory ammunition I uniformed the flash holes on the brass.
Bullets: 165 grain DEWC from Matt’s Bullets (Seated Flush by using an expander die, taper crimp in separate step.)
Primer: Rem 2 1/2
Powder: 0.7cc (Lee Dipper) Trail Boss
Brass: 1x Fired
Firearm 5.5″ Ruger Blackhawk with a 45 ACP cylinder
Spread: 784-748.5 = 35.5fps
Std Dev: 13.44 fps (6 shots)
LabRadar Series: 71
Notes: Clean burning. Clean holes. Mild recoil, but not recoil-free (~125 PF).
|Avg Vel||Spread||StdDev||N||Charge||Primer||LabRadar #||Notes|
|766||799-747=52||20.5||6||3.0 Red Dot||Rem 2 1/2||S97||Smelly|
|764||784-748.5=35.5||13.44||6||0.7cc Trail Boss||Rem 2 1/2||S71||Accurate and good holes|
|591||615-546=68||30.4||5||0.5cc Trail Boss||Rem 2 1/2||S99||Smelly|
|517||554-494=60||32||3||2.0gr Clays||WLP||S98||“Crackling” burning powder in air. Some holes were not clean. Some shots were silent with no hole, but clear bore.|
|411||6||3.1||3||1.5gr Clays||WLP||S100||No crackeling|
|580||603-551=52||16.9||12||2.0gr TiteWad (3BR #18)||WLP||S104||Unburned powder in case|
|467||480.5-452.5=28||14||3||1.5gr TiteWad (3BR #15.25)||WLP||S105||Unburned powder in case|