Heavy Hitting with the 45 Colt
Joseph D'Alessandro Editor
There is an increasing trend for handloaders to work
to a firearm's limit rather than a cartridge specification. The idea
is that a cartridge pressure spec is scaled to the original firearm
it was assigned, so when that cartridge is moved to a stronger
action, it should be able to sustain higher pressure. This concept
is clearly illustrated by the 45-70 Gov't round. Loaded for the
original trapdoor Springfield MAP is 28,000 PSI, but loaded for a
Ruger No. 1 that can routinely handle the 458 Lott's 62,000 PSI,
handloaders for the 45-70 push 50,000 PSI.
A quick look in most component manufacturers'
reloading manuals will show the same for the 45 Colt with sections
dedicated to the Colt SAA and replicas and another section for Ruger
Blackhawks and some lever action rifles. The 45 Colt has a MAP spec
of 14,000 PSI. Handloading manuals usually have a Ruger section with
a pressure ceiling somewhere between 25,000 - 32,000 PSI, the range
mostly determined by the firearm types they include in the high
pressure section. As an example, manuals that include Contenders
tend to be more conservative with pressure.
Within the context of this article, brass plays
virtually no roll in establishing pressure ceilings. Cartridge cases
act as independent pressure vessels, they seal the chamber against
the breech face. 8,000 PSI is all it takes to expand a cartridge
case against the supporting steel pieces and from that point on it
is the steel surrounding the case that is withstanding the pressure.
The pressure it would take to flow brass out from pressure areas
would be high enough to cause the steel parts to fail.
The Downside of Pushing Handloads
The greatest problem confronting handloaders who push
cartridges is knowing what level of pressure is being
generated. Increases in quantities of powder do not have a
proportional result in pressure. Typically, the pressure curve
sharpens as more powder is added, except where some heavily
compressed loads, when used with magnum primers, result in lower
pressure. The theory is that the primer drives the unburned charge
against the bullet, forcing it forward and increasing the volume of
space open to the now burning powder. Handloads that utilize powders
designed for low pressure shotguns are frequently using a product
that hasn't been tested at high operating pressures, so burn
characteristics are often unpredictable. Reading brass, examining
primers, listening to rapport and measuring velocity offer pressure
level clues, but none are precise enough to safely determine
Excessive pressure damage can be accumulative.
Before metal parts burst they can be permanently stretched out of
tolerance and weakened by excessive pressure; bowed chamber walls in
some firearms is common. A handload may seem fine when fired a few
times, then suddenly cause a barrel or receiver to burst. From a
handloaders perspective, they may have survived a live fire test,
but they don't know if the load generated 40,000 PSI, 60,000 PSI or
79,000 PSI, or if the load is safe or a step toward future failure.
The only safe harbor for the handloader is to obtain pressure
checking equipment, or stay on the well documented path of
mainstream handload data.
How did I get so smart?
Unfortunately I didn't, however, I've learned to
recognize credible sources when I see them. Some of the data that follows is drawn from
mainstream handloading manuals, some from technical material
published by knowledgeable gunsmiths like
Linebaugh, some from my own experimentation and pressure
checking with an Oehler strain gauge setup and a test gun. In the
absence of these inputs I never would have thought the Ruger could
withstand these types of pressures. The cylinder wall thickness of a
45 Colt chambered Ruger is approximately .098". To put this in
context, the wall thickness of the Marlin Guide Gun is .346", plus
the wall thickness of the receiver of .116", which puts .462" or
almost half an inch between the chamber and the outside world.
Still, many people do not believe the Guide gun is designed to
withstand 40,000 PSI.
There are many ways to determine the strength of a
firearm. The first is theoretical based on calculation, mostly
addressing the issues of breech face thrust, and longitudinal,
radial and hoop stress, A second method is destructive testing; run
it up till it blows up, but this approach is a little costly. Linebaugh's article "The .45
Colt, dissolving the Myth, Discovering the Potential" is a good
piece of information because it offers H.P. White Laboratory destructive
test data and the author's interpretation of results. Linebaugh
concludes the Ruger Blackhawk is good for loads up to 32,000 CUP.
Firearms similar in strength are: Blackhawk, Super Blackhawk, Bisley, large frame Vaquero, and Redhawk
revolvers. Firearms that cannot withstand this type of pressure: small frame Vaqueros,
Colt SAA and
The Bullet Lineup
One of the problems associated with handloading for a
flexible cartridge is the number of possible component combinations.
I tried to pick a good cross section of cast and jacketed bullets
from light to heavy in weight.
|*Measured with Lee
lead hardness tester
**No longer cataloged
by Oregon Trail but available from Cast Performance
indicated above, bullets are of varying length, however, a cannelure groove typically insures the overall cartridge length will
not exceed 1.600"; the maximum length spec for the 45 Colt. The
Ruger cylinder, at 1.700", can accept longer cartridges as long at
the bullet ogive does not hit the throat just ahead of the chamber.
The Hornady 300 grain bullet has two cannelure positions; one .325"
up from the bullet's heel, the other .430". The Hornady manual
instructs us to use the top cannelure which yields a 1.600" overall
cartridge length. If assembled to the lower cannelure, the resulting
cartridge is 1.770"; too long for the cylinder and the bullet
contacts the throat .070" short of seating as illustrated in the
picture to the right.
Reports suggest Ruger single action revolvers run
over spec. Chamber diameter spec is
.486" my Ruger measures .478", the throat spec is .455"
measures .451". The gap between cylinder and barrel is .002" and groove diameter is .4505". Pretty tight gun.
Powder and Test Lots
done nothing special here because a narrow selection seemed to
provide enough choices and good performance. I selected Alliant
2400, Alliant Unique, Accurate No. 9, Hodgdon H110, and Winchester
At the left are my preliminary test lots. My first
pass after laying out load sheets is to produce three shot samples
of each load to see if I need to load up, stay where I am or reduce
a load. Once this is done, I'll produce larger quantities of each and
use these lots to check pressure and external ballistics. This is
where I am at the moment, piles of handloads and scheduling a range
Heavy Hitting with the 45 Colt Part I
Heavy Hitting with the 45 Colt Part II
It's Like a Winchester...Only
Handload Data -
45 Colt - Winchester '94 and Ruger Bisley