n9020351@unicorn.cc.wwu.edu (James D. Del Vecchio) (06/11/91)
I have this issue and last of Handgun Quarterly/ Shooting Times. A few items: Per mag maximum chamber pressure is about 35,700 cup for 38 super, 40 S&W, and 10mm Auto, vs about 19,900 max for 45 ACP. Why is this and what significance of it? Are the 45 cases weaker for some reason, or is it the construction of the pistols? Is it possible to make a 45 withstand the higher pressures? Thicker cases maybe? I've been told the 38 super and 10mm are both louder than the 45, is this entirely due to the higher muzzle pressure? Is the .40 also louder than the .45, say with the subsonic loads? According to their charts you can get more velocity using the same powder charges and bullet weights in a 4" 40 S&W than you can with a 5" 45. Why would this gun be more efficient? Jim Del Vecchio
boyd@mailer.cc.fsu.edu (Mickey Boyd) (06/12/91)
In article <35456@mimsy.umd.edu>, n9020351@unicorn.cc.wwu.edu (James D. Del Vecchio) writes:
#
#Per mag maximum chamber pressure is about 35,700 cup for 38 super, 40 S&W,
#and 10mm Auto, vs about 19,900 max for 45 ACP.
#
#Why is this and what significance of it? Are the 45 cases weaker for some
#reason, or is it the construction of the pistols? Is it possible to make
#a 45 withstand the higher pressures? Thicker cases maybe?
The .45ACP is a low pressure round. Way back in 190x, when the case was
designed, the common case construction method was called "ballooning". This
basically resulted in a case with less brass (but higher capacity) than cases
currently made today. Thus, cases made today are much stronger (in general)
than ones made 50 years ago or longer. For the "older" calibers, this is
quite common. Anyway, you can load a .45ACP "up" without harming the case,
but you could harm the gun (because it was designed with a certain power
level in mind). Also, if you stick one of these hotter loads in a really
old 1911, it might blow the gun up in your face!! Thus, the moral of the
story is that extra case strength does not mean you can increase loads
willy-nilly. Many variables exist in the "safe to shoot" equation, and
that is only one of them. DO NOT LOAD ABOVE CARTRIDGE SPECS UNLESS YOU
REALLY KNOW WHAT YOU ARE DOING, AND QUESTION YOUR SANITY EVEN IF YOU DO.
This might help also. The .45 long colt was originally a black powder
round. Thus, lots of room was needed to pack in enough black powder to get
the desired uumph. With modern (stronger) cases, and modern powders, you can
easily double or triple the performance of the old black powder ballistics.
However, if you go and buy .45 long colt ammo, you will find that it is loaded
to the "old" standards. Why? So the ammo company cannot get sued if you
stick a round in granddad's old peacemaker and blow the thing up!! If you
have heard of the .454 Casull round (with all it's power) you might be
suprised to find out that it is just a .45 Long Colt extended 1/10 of an
inch. The extention was done not to provide more powder room, it was done
to prevent a situation as described above. This is also true of the .357 mag
(which is a .38 Special extended 1/10 of an inch).
Now, here is another tidbit. A few years ago, Detonics introduced the
.451 Detonics Magnum. This was basically a modern .45ACP case (it may have
had some extra thickness at the base) extended so it would only chamber in
a barrel specifically cut for the .451 DM. Then they made a barrel/recoil
spring combo designed for the increased power level. Simple.
#
#I've been told the 38 super and 10mm are both louder than the 45, is this
#entirely due to the higher muzzle pressure?
#
#Is the .40 also louder than the .45, say with the subsonic loads?
"Loud" depends upon many other variables than just caliber, charge, pressure
or barrel length. Subsonic loads are "quiet" by design, since they are
intended for use in supressed weapons (so you defeat the sonic "crack"). Many
commercial .45acp loads are already subsonic (I seem to remember that the
speed of sound is about 850fps).
#According to their charts you can get more velocity using the same powder
#charges and bullet weights in a 4" 40 S&W than you can with a 5" 45.
#Why would this gun be more efficient?
Well, efficient is a relative term, dependent upon the goals in mind. The
.45ACP was designed around the "big bore size" idea, which states that
bullet size/weight is more important than velocity (after you get ballistic,
of course). The 9mm and .38 Super are members of the "smaller bullet hauling
ass is better" school of thought. The .40S&W is thought by some to be a
sort of compromise between the two. The 10mm was designed to work in larger
barrels than are commonly found on pistols (it was really intended for the
carbine/machine pistol type weapon), hence the creation of the identical
(except shorter) .40S&W, or 10mm Lite :-). So, in terms of efficiency,
the data you have mentioned above seems to indicate that you have given up
some bullet frontal area for velocity. Whether or not this is better depends
on which school of thought you subscribe to.
I was swayed from the "9mm" school of thought to the "45ACP" school of
thought when someone pointed the following out to me. I was carrying a
CZ-75 loaded with HydroShoks, when a buddy of mine pointed out to me that
if I managed to aim just right, and the bullet doesn't hit bone and close
up, and the bullet doesn't hit a soft spot and overpenetrate, and if the
consistancy of whatever it does hit encourages expansion, if all of these
things happen just right my bullet just might expand to about .45" in
diameter! Well heck, why not start there and make expansion optional? Note
that Jeff Cooper (who certainly knows what is up when it comes to guns and
terminal performance) carries flat point hardball ammo in his .45, because
he feels that the frontal area of the bullet is already big enough. Another
thing that "converted" me was the realization that in all probability
those extra rounds that the 9mm round allowed me (in my gun) would not
do me any good if I did not have time for more than one shot. Your first
is the most important, and has the best chance of hitting the target both
in terms of time and "stress shock".
The above is IMHO. Direct flames elsewhere :-)
--
Mickey R. Boyd | "God is a comedian playing to an
FSU Computer Science | audience too afraid to laugh."
Technical Support Group |
email: boyd@fsucs.cs.fsu.edu | - Voltaire petert@uunet.UU.NET (Peter Toth) (06/13/91)
In article <35507@mimsy.umd.edu> boyd@mailer.cc.fsu.edu (Mickey Boyd) writes: #In article <35456@mimsy.umd.edu>, n9020351@unicorn.cc.wwu.edu (James D. Del Vecchio) writes: ## ##Per mag maximum chamber pressure is about 35,700 cup for 38 super, 40 S&W, ##and 10mm Auto, vs about 19,900 max for 45 ACP. ## ##Why is this and what significance of it? Are the 45 cases weaker for some ##reason, or is it the construction of the pistols? Is it possible to make ##a 45 withstand the higher pressures? Thicker cases maybe? # #The .45ACP is a low pressure round. Way back in 190x, when the case was Was it 1906 that the German Namvy accepted the 9x19 (aka 9Luger, 9NATO) as their sidearm round? It too has a SAAMI max pressure of 35700. Maybe age was not the reason. Maybe JMBrowning wanted light pistols. #designed, the common case construction method was called "ballooning". This #basically resulted in a case with less brass (but higher capacity) than cases #currently made today. Thus, cases made today are much stronger (in general) Apparently JMBrowning produced the prototype cases by hacking the .30-06 cases to .90 inch. Since the 06 runs at circa 45000, it wasn't the case: it was the thickness of the chamber, as Mickey points out below. #than ones made 50 years ago or longer. For the "older" calibers, this is #quite common. Anyway, you can load a .45ACP "up" without harming the case, #but you could harm the gun (because it was designed with a certain power #level in mind). Also, if you stick one of these hotter loads in a really #old 1911, it might blow the gun up in your face!! Thus, the moral of the #story is that extra case strength does not mean you can increase loads #willy-nilly. Many variables exist in the "safe to shoot" equation, and #that is only one of them. DO NOT LOAD ABOVE CARTRIDGE SPECS UNLESS YOU #REALLY KNOW WHAT YOU ARE DOING, AND QUESTION YOUR SANITY EVEN IF YOU DO. #[... rest of great article deleted ...] Like Mickey said. Peter Toth
bressler@uunet.UU.NET (Rick Bressler) (06/15/91)
James D. Del Vecchio writes:
# I have this issue and last of Handgun Quarterly/ Shooting Times.
#
# A few items:
#
# Per mag maximum chamber pressure is about 35,700 cup for 38 super, 40 S&W,
# and 10mm Auto, vs about 19,900 max for 45 ACP.
#
# Why is this and what significance of it? Are the 45 cases weaker for some
# reason, or is it the construction of the pistols? Is it possible to make
# a 45 withstand the higher pressures? Thicker cases maybe?
While I'm not positive, (I haven't examined anything but the .45 action
in this list) I suspect that the cases of these newer rounds are fully
supported by the actions, while the .45 is NOT. This translates into
part of the case not being reinforced by the action and is therefore
unable to take the pressures that a fully supported case can.
I think the problem is similar to that of the .44 special. The .44
special can be loaded nearly to Magnum velocities. However, this round
was designed in the late 1800's and there are still many non-magnum guns
out there. Therefore, the ammunition manufacturers have to load the .44
special to the least common denominator. The eventual solution to this
problem was the creation of the .44 magnum. The case was made a tiny
bit longer so that it wouldn't fit into the older .44 special guns. It
was then loaded up to magnum pressures. If you have a NEW .44 special
(there aren't many made any more) or a .44 magnum, you have great
flexibility on how you load the .44 special case. The .45 ACP is also
an 'old' round. The original designs for this gun didn't fully support
the case, so all ammunition has to be loaded to these specifications.
I have a friend with a semi auto Uzi in .45. This particular action
fully supports the case, and he has slowly been working up to much
higher pressure loads. So far, he is approximately 50% or more over a
'standard' .45 load with none of the classic signs of high pressure.
Don't remember his exact chronograph readings, but these loads are
really zipping along. He figures (I don't know how) that his loads are
approaching 28-30,000 cup. As the usual, the disclaimer 'don't try this
at home' applies!!!!
#
# I've been told the 38 super and 10mm are both louder than the 45, is this
# entirely due to the higher muzzle pressure?
In general, higher pressure loads will have more muzzle blast, all other
things being equal. (Barrel length etc).
#
# Is the .40 also louder than the .45, say with the subsonic loads?
Can't say on this one.
#
# According to their charts you can get more velocity using the same powder
# charges and bullet weights in a 4" 40 S&W than you can with a 5" 45.
# Why would this gun be more efficient?
As you said, these loadings yield higher pressure in the .40. In
general, higher pressure = higher velocity. (Sorry if I'm stating the
obvious). The reasons that you get higher pressure from the same load
are many. It depends on how much empty space there is in the case, bore
diameter, bullet weight, powder burning rates and a whole bunch of other
things. In this case, remember that while the bullet weight is the
same, the diameter is smaller by a fair margin, and the case capacities
are quite different. These are probably the primary differences. Also,
powders can burn quite differently under different conditions. There
are whole books written on the subject. That's why most of us hand
loaders rely on others to work up new loads! It doesn't pay to try
guess about what any particular new load might do. Even the very
experienced tend to leave this to the 'experts'.
#
# Jim Del Vecchio
# ----------
Rick.gary@gatech.edu (Gary Coffman) (06/15/91)
I'm going to tackle this and ask the real experts to straighten out any
mistakes I might make. I've got a couple of questions of my own.
In article <35456@mimsy.umd.edu> n9020351@unicorn.cc.wwu.edu (James D. Del Vecchio) writes:
#Per mag maximum chamber pressure is about 35,700 cup for 38 super, 40 S&W,
#and 10mm Auto, vs about 19,900 max for 45 ACP.
#
#Why is this and what significance of it? Are the 45 cases weaker for some
#reason, or is it the construction of the pistols? Is it possible to make
#a 45 withstand the higher pressures? Thicker cases maybe?
.45 cases are solid head and plenty strong. The 1911 is the limiting
factor. It's delayed blowback design and lack of full cartridge head
support limit the pressure it can tolerate. High pressure loads will
not drop in pressure enough during the delay time when the slide and
barrel are moving backwards together and it will unlock before pressure
has dropped enough. Also the hotter load will cause stronger recoil
and hammer the gun severely leading to eventual failure. You can shoot
much hotter loads in a Contender where the case is fully supported and
the action remains locked until you reload.
#I've been told the 38 super and 10mm are both louder than the 45, is this
#entirely due to the higher muzzle pressure?
Yes. Now here is where I turn to the experts. A small charge of fast burning
powder will have higher peak chamber pressure than a larger charge of slower
burning powder. But, unless the cartridge is way over bore capacity, the
muzzle pressure as the bullet exits will have dropped so much that the higher
pressure charge is quieter. Is there a formula relating expansion ratio,
peak pressure, muzzle pressure, burning rate, bullet mass, and velocity?
#Is the .40 also louder than the .45, say with the subsonic loads?
That depends on the load. If the velocities and bullet masses are the
same, then yes the .40 should be louder. But the other factors of burning
rate and expansion ratio must be considered. I'm not sure that a load
*has* to be louder in the .40 to deliver the same velocity. Can the
experts comment?
#According to their charts you can get more velocity using the same powder
#charges and bullet weights in a 4" 40 S&W than you can with a 5" 45.
#Why would this gun be more efficient?
This has to do with something called "bore capacity". The same charge
in a smaller cartridge expanding into a smaller bore will deliver more
pressure to the bullet during the entire time it is in the bore. The
increased pressure over the dwell of the bullet in the barrel more than
offsets the reduced base area of the .40 bullet vs the .45 bullet so the
velocity is greater. There is an ideal point. If the bore is too small,
the cartridge will be over bore capacity and much of the pressure will
be wasted as muzzle blast. If the bore is too large, the cartridge will
be under bore capacity and the pressure will drop too much before the
bullet leaves the barrel. For a severely under bore cartridge, the
bullet can actually slow down in the barrel due to frictional losses being
higher than remaining pressure.
There is a relationship between exterior ballistics and interior ballistics
that determines ideal cartridges. In rifles, the 7mm bullet has ideal
exterior ballistics, there is an ideal 7mm cartridge that has complimentary
interior ballistics, it's the 7x47 wildcat. A question for the experts,
what is the ideal pistol cartridge based on similar reasoning? Is that
cartridge in commercial production, or has it been wildcated, or does it
remain a theoretical design?
Garygary@gatech.edu (Gary Coffman) (06/15/91)
In article <35507@mimsy.umd.edu> boyd@mailer.cc.fsu.edu (Mickey Boyd) writes:
#
#I was swayed from the "9mm" school of thought to the "45ACP" school of
#thought when someone pointed the following out to me. I was carrying a
#CZ-75 loaded with HydroShoks, when a buddy of mine pointed out to me that
#if I managed to aim just right, and the bullet doesn't hit bone and close
#up, and the bullet doesn't hit a soft spot and overpenetrate, and if the
#consistancy of whatever it does hit encourages expansion, if all of these
#things happen just right my bullet just might expand to about .45" in
#diameter! Well heck, why not start there and make expansion optional? Note
#that Jeff Cooper (who certainly knows what is up when it comes to guns and
#terminal performance) carries flat point hardball ammo in his .45, because
#he feels that the frontal area of the bullet is already big enough. Another
#thing that "converted" me was the realization that in all probability
#those extra rounds that the 9mm round allowed me (in my gun) would not
#do me any good if I did not have time for more than one shot. Your first
#is the most important, and has the best chance of hitting the target both
#in terms of time and "stress shock".
I've seen a man drop stone cold dead from a single .22 round. I've seen
a man with 5 .45 slugs in him badly maul 6 police officers. The variability
of human response to penetrating wounds is so extreme that the question of
9mm vs .45 seems moot. High velocity rounds do seem to cause a momentary
stun effect that may allow you time to deliver a well placed followup
shot. Unless you are the assailant, you rarely have the luxury of a
well aimed first shot. Your first shot is likely designed to get the
assailant's head down and stop him from shooting at you *again*. Your
mileage may vary.
Garybercov@bevsun.bev.lbl.gov (John Bercovitz) (06/15/91)
In article <35657@mimsy.umd.edu> ke4zv!gary@gatech.edu (Gary Coffman) writes: #I'm going to tackle this and ask the real experts to straighten out any #mistakes I might make. I've got a couple of questions of my own. ##In article <35456@mimsy.umd.edu> n9020351@unicorn.cc.wwu.edu ##(James D. Del Vecchio) writes: ##Per mag maximum chamber pressure is about 35,700 cup for 38 super, 40 S&W, ##and 10mm Auto, vs about 19,900 max for 45 ACP. ##Why is this and what significance of it? Are the 45 cases weaker for some ##reason, or is it the construction of the pistols? Is it possible to make ##a 45 withstand the higher pressures? Thicker cases maybe? #.45 cases are solid head and plenty strong. The 1911 is the limiting #factor. It's delayed blowback design and lack of full cartridge head #support limit the pressure it can tolerate. High pressure loads will #not drop in pressure enough during the delay time when the slide and #barrel are moving backwards together and it will unlock before pressure #has dropped enough. Also the hotter load will cause stronger recoil #and hammer the gun severely leading to eventual failure. You can shoot #much hotter loads in a Contender where the case is fully supported and #the action remains locked until you reload. I'm no expert (Ed Harris and Gale Barrows are, though; what happened to ya Ed, ya fall off the net?) but I'll critique your comments some: The 45 case is pretty strong and will hold up to most abuse at least until you "ramp" the entrance to the chamber so it will feed those good old Hornady #4515s. Then your case gets a little bulgey if you go too much over nominal. So next you have to get into cutting down 308 cases or some other similar foolishness. ("pretty strong"? What's this? Lake Wobegone?) The 1911 is _not_ a delayed blowback pistol. It is a locked-breech pistol. Delayed blowback means you've got some scheme for making a blowback pistol delay its slide opening enough that the case doesn't blow out. A "classical" blowback or delayed blowback pistol will have no relative motion between barrel and frame during the firing cycle. Unless a 1911 is busted, the chamber pressure will have fallen very low by the time the barrel/slide unlocks because the bullet has left the barrel by the time the barrel unlocks from the slide. This is so because of basic momentum transfer principles which are pretty hard to circumvent. The following is "in my very limited experience": I agree that hot loads accelerate the usual failure modes of frame cracking and underlug shearing and that sort of stuff. But the REALLY hot loads wear out the barrel-groove/ slide-groove locking surfaces first. They just sort of peen over on you and pretty soon you've got no locking surfaces left - they're not 90 degrees to the bore anymore. At this time, you can say you've really screwed up. [ many questions in the area of internal ballistics deleted ] I'm not at all strong in internal ballistics so I should leave it alone. (Why should I let _that_ stop me?) 8-) But a few clues: When discussing fast and slow powders and resultant velocities, you might think in terms of integral P(V)*dV. In my experience, if you compare the exit gas pressure of a load which contains a maximum charge of fast powder to the exit pressure of another load which uses a slower powder but has the same resultant muzzle velocity, you'll find the two exit pressures are very similar. At least that's what happened when I did the internal ballistics testing with the 45 ACP cartridge, results of which I reported here a couple or so weeks back. I would guess that the amount of noise coming from the muzzle will be some- what related to the stored energy of the gas which is in the barrel at the time the bullet exits. The stored energy is: U = [(P1*V1)/(k-1)]*[1-(P2/P1)^((k-1)/k)] where k is Cp/Cv, P1 is the exit pressure, P2 is the ambient pressure (14.696 psi), and V1 is the volume of the bore and chamber added up. Only I can't remember the value of k for the products of combustion of smokeless. (It's hell getting old and I ain't even old yet.) Anyone remember it? You can bet someone in rec.pyrotechnics does. This might be controversial, but I would say that there's probably no such thing as either an underbore or overbore cartridge. The only reason that we say that a 50 BMG necked down to a phonograph needle is overbore is that there is currently no powder made which is slow enough to burn in it. (Another problem with the 50 BMG/phono needle is that it's a little noisy.) Underbore just means your efficiency of energy transfer from powder to bullet is getting so darn good that you can't hardly stand it anymore. If the bullet starts to slow down in the barrel, the barrel's too long. I don't know how to size the case volume to the bore for maximum accuracy. Dan Powlak did. Mike Walker does (did? I hope he's still around). I don't think many people _really_ know. JHBercovitz@lbl.gov (John Bercovitz)