Estimate chamber pressure and muzzle velocity for the 45 Automatic +P with the free,
in-browser MyLoads internal ballistics simulator. The figures below are illustrative
estimates from a physics model — not a recommended load. Always cross-check a current
published loading manual.
45 Automatic +P reference
Maximum average pressure (MAP)
23,000 psi
Nominal case capacity
26.0 gr H₂O
Groove / bullet diameter
0.451 in (11.46 mm)
Example simulation illustrative
Bullet
Barnes .451 185 gr TAC-XP FB
Powder
Ramshot Silhouette
Charge
7.3 gr
Barrel
5 in
Muzzle velocity
1,036 fps
Peak chamber pressure (interval, ±10% burn rate)
17,365 – 21,985 – 27,161 psi
nominal is 96% MAP (23,000 psi)
This sample load runs near MAP for the 45 Automatic +P (about 96% MAP at the nominal estimate; the upper interval can exceed it). It is shown only to illustrate the simulator — reduce the charge and work up from your manual's start load.
The simulator isn't optimized for this cartridge yet and may read pressure high.
Illustrative example — every figure is an estimate; always confirm your load against a current published manual before loading.
Popular 45 Automatic +P powders
Powders and bullets handloaders commonly use for the 45 Automatic +P, drawn from public discussion and listed most common first. They appear as the Popular group in the calculator's pickers. This is not a load recommendation — always check your load against a current published manual.
Alliant Power Pistol
Hodgdon HS-6
Hodgdon Longshot
Hodgdon CFE Pistol
Alliant Blue Dot
Ramshot Silhouette
Winchester AutoComp
Vihtavuori N320
Vihtavuori N350
Accurate No. 5
Ramshot True Blue
Popular 45 Automatic +P bullets
Speer Gold Dot GDHP .451 200 gr
Hornady 0.451 200 gr XTP
Hornady 0.451 185 gr XTP
Speer Gold Dot GDHP .451 185 gr
Hornady 0.451 230 gr XTP
Speer Gold Dot Short Barrel GDHP SB .451 230 gr
Nosler ASP 45 Cal 185 gr JHP
Sierra 45 Caliber (.4515) 185 gr JHP Sports Master
Barnes .451 185 gr TAC-XP FB
Use MyLoads as a 45 Automatic +P velocity and pressure calculator: it estimates
muzzle velocity, muzzle energy and the full chamber-pressure curve for your own powder,
charge and barrel length, compared against the reference facts above.