Cowboy Ammo Pressure Curve

rhmc24

I posted this on "Ask the Expert" but here is probably better.
Is there factual info as to the difference between the pressure curve of cowboy ammo compared to standard? Ballistics, for example, .44 Special standard and cowboy are very close, within 5 to 10 units in bullet weight, velocity and energy. In shooting the two, the cowboy seems a bit less noisy, recoil and much dirtier than the Special. If pressure curve info is available, I would appreciate the info. One wonders why a cowboy round exists, considering the rarity of "cowboy type" revolvers in that caliber.

This is the pistol discussed below:

mbsams

I guess it's taking a long time to get a response to your post as we are all taken aback that a senior member with 1627 posts would write such a post. First, those bullet weight units are "grains", the same grains we use to weigh powder. Next, a "cowboy" load only refers to reduced loads ( usually lead bullets ) for the target shooting done at cowboy events. Such loads are easy on the shooter and the firearm. As to the "pressure curve". It varies with powder type, bullet weight and hardness, barrel length and many other variables. It is generally of no concern when you follow published procedures and data for reloading.

rhmc24

I guess it's a case of "different strokes for different folks" --

Curiosity is good enough reason for me but there is a difference in pressure propagation in explosives. Like the difference between a jerk and a steady pull. An explosive with an instant pressure build-up might be best for mining or cracking rock while one with a slower expansion would be better for propelling a bullet down a gun barrel - or sending a rocket on its way.

I suspect cowboy loads are designed to start the bullet with an easier push to protect the old and marginal guns that some users employ.

As a teenager (1930s) I desperately needed black powder for cap and ball pistol shooting. Made up a batch from highschool chem lab using potassium chlorate rather than p-nitrate. Blew up a good gun. Later I learned I had made blasting powder. Live and learn. That is reason enuf for me to pose my question.

dandak1

If different powder is used there will definitely be a different pressure curve, which is why they make so many different powders (different pressure curves needed for different bullet weights and different barrel lengths). As far as your specific 44 spl vs cowboy load I cannot answer. One time, years and years ago, I saw various graphs of pressure curves for various ammo....I think but cannot definitely say for sure, it was in an old issue of American Rifleman. Otherwise it is probably info manufacturers figure we dont need. Maybe try the ammo manufacturers website and click on 'contact us' and ask them via email if they have the curves available. I have contacted many companies this way that i normally would not, and have received some pleasant surprises...there are a lot of companies out there that still appreciate a customer and treat them like they are #1.

44caliberkid

The "cowboy load" is not to protect old or marginal guns. 99.9% of the guns used in CAS are new manufactured replicas of modern steel and will use +P rounds as well as low pressure rounds. The reason for the "cowboy load" is two fold. One is shooter and spectator safety, as we shoot steel plates and the bullets bounce back. It's not unusual to feel bullet fragments strike you during a match, although targets are usually angled downward to deflect the bullet into the dirt.
The second reason is longevity of our steel targets. The mild load and soft lead bullet don't dent or penetrate the 3/8 to 1/2 inch mild steel we use for the plates. Our targets have been used for 10 years and been struck by thousands of rounds and all they need is a shot of spray paint twice a season.
There are lots of cowboy revolvers in 44 special. Uberti 1873's, Ruger Vaquero's in 44 mag (that shoot 44 special) and USFA's and 3rd gen. Colt's in 44 Special.

rhmc24

Thanks for useful info. I'm interested in .44 Special for my S&W DA top break that I reamed from 44 Russian a little deeper. More .44Specs
than I thought with all those you listed.

44caliberkid

I wouldn't use any smokeless load for that S&W DA. They were made for BP and the pressures for smokeless, even in reduced loading, are too much. You will have an excessive headspace problem in short order. I know because I have 3 of them and all but one has excessive headspace (but not from anything I did). Have someone make you some rounds with APP powder, as it doesn't foul, cleans with water and you can use modern wax bullet lubes. Not sure why you reamed it as there are 44 Smith & Wesson (Russian) brass and loaded ammo available.

rhmc24

I recognize there are cautions. I'm wondering about how many rounds translate to "short order". It has about 100 rounds of .44 Spec with no indicaion of change I also suspect you mean cyl/bbl gap will increase. From what I can learn, the basic .44 Special and Russian are loaded the same. I shoot .44 Spec cowboy when I can get it. Never been able to get Russian locally. I don't reload and don't plan to.

I have the same gun in 44-40 which has about .020" gap, otherwise VG. Maybe someone was shooting it a lot or with ammo intended for rifle. I plan to fix it when I catch up on client work. The fix is to lengthen the button in center of the ejector star.

These old guns will take more of a beating than you might think. As a kid I had a Scofield that had the cylinder turned to accept .45 Auto Rim which I shot a lot.

ruger41

I think I may have found something to help you rhmc24. Hogdon has a load data page where you can input all kinds of different cartridges and it will give you the CUP(copper units of pressure) of each with comparisions of at least 20 different powders and all various bullet weights. Now granted this will not give you FACTORY pressure levels but it will be darn close if you take a close look at the various powders & bullet weights you will see which ones have a higher pressure. Having said that I would be very careful firing smokeless loads through that gun-it was never designed with the .44 Special cartridge in mind-smokeless and blackpowder operate at different levels and you are IMO flirting with disaster by shooting smokeless .44 Specials in it. There are black powder .44 Special factory loads already available if you do not reload from Goex and can be bought at Midway http://www.midwayusa.com/viewProduct/?productNumber=611372

Here is the Hodgon page so you can at least get an idea of the pressures being created. http://data.hodgdon.com/cartridge_load.asp

rhmc24

Thanks ruger41 for your interest. I looked at the website info you refered me to - only looked but not studied it yet. Years ago I was a SAE member interested in fuel, detonation, etc. A problem was that as engines got higher compression, fuel knock (ping) occurred. The early solution was to add tetraethyl lead to the fuel to delay the pressure rise after ignition. The result was the same total pressure available to push the pistons but spread over a longer time. There were various pressure curves that illustrated in microseconds what the pressure was doing with/without additives, different fuels, etc.

I'm sure the powder makers design their products to so something similar and their engineers have their own versions of pressure curves they work with in making design changes. I was hoping someone might come up with some of that info.

44caliberkid

As far as pressure curves go, and this is just very general info, blackpowder spikes (peaks) almost immediately upon ignition, then drops off, whereas smokeless is more of an arc, the pressure maxing out a little later than at ignition. That's why damascus shotgun barrels blow just ahead (about 8 inches) of the chamber when fired with modern smokeless rounds. With black, the pressure was already dropping as the charge moved down the barrel. Could also be the reason old revolvers stretch, high pressure between the breech and the bullet a few inches into the barrel, pulls on the front of the frame.
The Smith fix will solve the excessive headspace, as far as primer ignition (strike) goes, will will still leave you with a large barrel/ cylinder gap, because you are pushing the cylinder to the rear with the spacer.
What is short order? Well, with .32 S&W's, like a model 1 1/2, you will stretch the frame with one cylinder full of smokeless ammo. A lot of good pocket pistols have been screwed up this way. In fact, it is hard to find good Smith's today without excessive for and aft cylinder play.
I have one of the Belgian copies of the S&W DA that says it's a 44 WCF, however the chamber is straight bored, no taper, and when fired with 44-40 cartridges, turns them into straight wall cases. It will chamber anything from 44 Russian to 44 magnum, which is why I would salvage it for parts or destroy the cylinder before I'd sell it. Unless it was someone who understood the limitations and inherent dangers of this flaw.

rhmc24

44cal is one of few with a handle on the issue. Hopefully some comments before this gets locked -- The curve is what I would like to see in hard copy. The design of the S&W DA holds the cyl/bbl gap close by the center of the ejector star contact with the recoil shield (frame). Frame stretch and wear at the contact point at/of the frame is seen as increased cyl/bbl gap - as well as increased headspace. Adding material at the aforesaid 'star contact center' closes the cyl/bbl gap & increases headspace by that amount. Extreme case will find the firing pin short of the primer.

My 44-40 mentioned is the only one (of 10 - 4 are 44-40s) of these DAs that has the gap problem, yet no indication of frame or other stretch. Top latch is still as good as the best. Actual stretch would load the latch-to-frame point - which is not seen.

I am ending this subject on GB forums. I will be pleased to discuss via profiles if anyone is interested. Thanks to all for your interest.

williamsmith

The Smith fix will solve the excessive headspace, as far as primer ignition (strike) goes, will will still leave you with a large barrel/ cylinder gap, because you are pushing the cylinder to the rear with the spacer.
What is short order? Well, with .32 S&W's, like a model 1 1/2, you will stretch the frame with one cylinder full of smokeless ammo. A lot of good pocket pistols have been screwed up this way. In fact, it is hard to find good Smith's today without excessive for and aft cylinder play.

rhmc24

Here is factual info from experience using my .44-40 mentioned above. It fixes BC gap and maintains correct headspace. Tools used were micrometer, feelerguage and dial indicator.

To begin with the BC gap was max at .018" when the fore & aft slop of the cylinder was taken up and headspace was zero with a cartridge loaded. I put in a spacer of .014 between the lower side of the ejector star and the cylinder. That gave a BC gap of .007 and headspace of .003" with the cartridge loaded - pretty much ideal.

The abovementioned spacer reduced the cylinder end play to .003" without cartridge loaded. Take note that movement of the cylinder rearward is controlled by the button in the center of the star interfacing the frame (recoil shield). Further, the action of the spacer vis-a-vis CB gap can also be obtained by lengthening the aforeemenationed ejector button by the desired amount. Chicoine in his book "Gunsmithing Old West Guns" reccos drilling-threading and inserting a screw. He mentions that it leaves the headspace increased and in max cases the firing pin may not penetrate the primer far enough.

Later, same day. With above success I made a washer .015" thick from sheet metal and installed it around the hex rod that pushes the ejector star. Works perfectly mechanically with a few rounds in the cyl that I have available. I will leave it there and shoot it as soon as I can find some 44-40 cowboy. To be continued.

melkor

USE BLACK POWDER OR Proper substitute in BLACK POWDER GUNS ! PERIOD ! DO NOT USE SMOKELESS if it is not a smokless PROOFED gun ! [:D]