Strange pressure question

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Wb1971

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Unfortunately this is going to be a long winded question. And please be gentle. I am new to reloading. Not brand new but one year so I consider myself new. I reload for and shoot a ruger vaquero among others. My question is about the vaquero loads. It is a vaquero in 45 Colt…not a “new” model vaquero. So from what I understand it can handle decent loads. Up to 30k or 33k depending on where you read. As of now I have only loaded lighter loads that are published. I wish this to NOT be a vaquero discussion…just trying to lay some ground work for a troubling question I have.
So let’s say I want to load a bit heavier load for whatever the reason. Of course pressure will increase. If this weapon can handle higher pressures…will the brass show over pressure signs while the weapon is not considered over pressured? I guess I am asking will the brass only show signs of over pressure if the chamber is over pressured? Or if the brass is over pressured while the weapon is not considered over pressured? Does that question make sense? Thanks to any that can explain this to me.
 
Brass will take it just fine, keep a eye on the primers and brass will get sticky when up there on pressure. Someone with more Knowledge on loading for revovers should be better to answer your questions.welcome to THR
 
When revolver ammunition starts into overpressure regimes -- for that particular revolver -- the load temporarily over-stretches [egg-shaping] the cylinder bore... allowing the the brass to over-expand/go egg-shaped as well.

The steel cylinder returns to "normal," but the over-stretched/egg-shaped case now "sticks" in the smaller round bore.

Sticky cases when extracting --> moving into overpressure.




Unfortunately, primers won't tell you anything... unless WAAAaaay over-pressure.
 
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Thanks Troy. So from what you’re saying I take it that brass will only show pressure signs if the chamber is experiencing over pressure problems. Correct?
 
I’ve got an older Vaquero in .45 Colt…

Yes, it will handle Ruger-only loads, but I don’t recommend a steady diet of them.

As long as your cylinder is true, your brass will be fine. In my experience, you really have to push the pressure up to get sticky extraction… so don’t use that as an indicator, either.
 
Without pressure measuring equipment, your best indicator of peak pressure is muzzle velocity.

At this point, someone often chimes in with the news that muzzle velocity is actually determined by area under the pressure curve, and that's true. But for an individual firearm, and one type of powder, area under the curve is highly correlated with peak pressure. So muzzle velocity is highly correlated with peak pressure. You can use your chronograph as a good relative indicator of muzzle velocity.
 
There are distinctly different brass alloys for different pressure thresholds. Might want to verify brass before exceeding its limits. Rifle brass has a higher zinc content, thus it is harder. Handgun brass has a higher copper content, thus it is softer. If you use fired brass as a braze alloy, you will see a distinct difference in higher zinc alloys. Copper "wets out" where zinc wants to ball up & not flow when melted. 556 brass is difficult to braze with, 38 specials work great. The point is, not all brass is the same.
 
Barring manufacturing flaws in the case head, the strength of any competent revolver
is in the fully-enclosed steel cylinder/wall thickness/yield threshold -- not the brass.

Velocity varies from barrel length, to internal dimensions, to cylinder gap, to phase of the moon.
Primers (barring gross overpressure) aren't all that helpful at normal handgun pressures.

With nothing else to go on... no chronographs, no pressure transducers, no calibrated
internal ballistics software, no published data (and sometimes not even with that) . . .

….Take care to monitor extraction getting sticky.


.
 
Unfortunately this is going to be a long winded question. And please be gentle. I am new to reloading. Not brand new but one year so I consider myself new. I reload for and shoot a ruger vaquero among others. My question is about the vaquero loads. It is a vaquero in 45 Colt…not a “new” model vaquero. So from what I understand it can handle decent loads. Up to 30k or 33k depending on where you read. As of now I have only loaded lighter loads that are published. I wish this to NOT be a vaquero discussion…just trying to lay some ground work for a troubling question I have.
So let’s say I want to load a bit heavier load for whatever the reason. Of course pressure will increase. If this weapon can handle higher pressures…will the brass show over pressure signs while the weapon is not considered over pressured? I guess I am asking will the brass only show signs of over pressure if the chamber is over pressured? Or if the brass is over pressured while the weapon is not considered over pressured? Does that question make sense? Thanks to any that can explain this to me.
Assuming I am understanding your question correctly? My indicator for a revolver load that is over pressure is this, the empty shells are stuck in the cylinder. This tells me that the cartridge case has expanded the cylinder's chamber wall and this is not a good thing. Brass is malleable and steel is more static, when the steel is stretched it is more likely to return to it's original dimension where the brass will not.
 
Thanks for all the great responses guys. I now have a better understanding. I do have a chrono and I am not looking for a beast load by any stretch. I just want a little more to flatten my trajectory a little at yardage. I really appreciate the help!!!
 
In reloading, everything we do is to control Chamber Pressure. Chamber Pressure is the devil we live with.

1. Yes, the steel cylinder will expand and contract. BUT, steel also remembers these events. At some point, after numerous abusive expansion/contraction cycles, it will give up. This is a special area of metallurgy called metal fatigue. When steel enters this realm depends upon multiple specifics you do not know. Failure due to fatigue is most always determined after failure. (In these type situations, usually at trail, in a case brought by your widow.) The point is, if your brass is sticking, then you not only need to "back off", you need to back WAY OFF.

2. Yes, if you are using a chronograph, then you can accurately equate chamber pressure to velocity, within strict limits. BUT you must remember that pressure testing is done in test barrels that are typically longer than your handgun. Therefore when testing your ammo's velocity, you may need to stay below the reported velocity.

Also, I say "within strict limits" because the linkage of velocity and chamber pressure only holds within published load ranges. Somewhere at pressures higher than published, velocity and chamber pressure part ways, and velocity no longer predicts the danger of rogue pressure.


All this to say, consider your high pressure loads very carefully.
 
My indicator for a revolver load that is over pressure is this, the empty shells are stuck in the cylinder. This tells me that the cartridge case has expanded the cylinder's chamber wall and this is not a good thing.

As I mentioned in my previous post... my Vaquero will almost drop shells out, even ones in the Ruger only zone. My Dan Wesson (.41) on the other hand, has to have them punched out no matter. The cutter used on my DW's cylinder must not have been true... you can see mild impressions on the brass from the imperfect walls... those imperfections allow the brass to grip the cylinder walls, even with moderate .41 loads. That's why I said it won't necessarily be an indicator... every pistol is different.

I do agree, also, with handgun primers not being a definite indicator. The only time I've seen a flat primer in a standard handgun round was with some 9mm handloads that, in hindsight, I know were overpressure. Even W296 loads under a 250grn bullet in my .41 don't mash primers that flat.

OP, best advise I can give you is to use reliable loading data, with the understanding that the closer you get to published maximums, the more you really need to pay attention to your reloading process (to eliminate variables) and to what the components are telling you (that is, velocity, recoil impulse, report, and the condition of your fired brass.) The .45 Colt is tricky... particularly in something like a Ruger... where you might think a maximum standard load right off the bat won't necessarily give you problems, simply because the pistol can handle 'Ruger only' loads... but that's not true either. A maximum standard load of a fast powder (think TiteGroup, etc) under a heavy bullet could easily result in pressure issues if the bullet is seated too deep, or you use other data that gives you a higher max. Peak pressure is the issue.

Further, assuming you continue on with the .45 Colt and get another pistol... you will need to be darned sure you don't mix up loads intended for the Ruger, and shove them into a Uberti or similar replica pistol... that is not intended for Ruger pressures.
 
In reloading, everything we do is to control Chamber Pressure. Chamber Pressure is the devil we live with.

1. Yes, the steel cylinder will expand and contract. BUT, steel also remembers these events. At some point, after numerous abusive expansion/contraction cycles, it will give up. This is a special area of metallurgy called metal fatigue. When steel enters this realm depends upon multiple specifics you do not know. Failure due to fatigue is most always determined after failure. (In these type situations, usually at trail, in a case brought by your widow.) The point is, if your brass is sticking, then you not only need to "back off", you need to back WAY OFF.

2. Yes, if you are using a chronograph, then you can accurately equate chamber pressure to velocity, within strict limits. BUT you must remember that pressure testing is done in test barrels that are typically longer than your handgun. Therefore when testing your ammo's velocity, you may need to stay below the reported velocity.

Also, I say "within strict limits" because the linkage of velocity and chamber pressure only holds within published load ranges. Somewhere at pressures higher than published, velocity and chamber pressure part ways, and velocity no longer predicts the danger of rogue pressure.

All this to say, consider your high pressure loads very carefully.

Good post. Let me add to the fatigue warnings:

You over stress the structure with loads that are above the design loads, don't expect your structure to last long. This post, on another forum, it is worth looking at the fatigue curve, and the blown up Ruger pistol.

Fatigue Life of 4140 steel

http://castboolits.gunloads.com/showthread.php?150409-Ruger-om-44-convertible&highlight=convertible

Just a few thoughts on this. For Background I am a mechanical engineer with a heavy background in failure and fatigue. I wonder if I could request a high quality photo of the fracture zone of the cylinder? I am specifically interested in the grain structure of the bolt notches.

I put fort the following.

1) Firearms in general (the type we plebeians can get our mits one) are not designed for infinite fatigue life.

2) The Factors of safety used in firearms design are in line with low end of fatigue requirements (usually less than 10,000 cycles).

3) One of the funny things about fatigue is that each time you push the material past its original design point, you lower its expected life.

4) I am looking at this as an older gun with an unknown number of rounds through it. but based on its age a substantial round count seems likely.

5) When these firearms are designed it is generally preferable for something else to go before the cylinder lets go and takes the top strap. Generally this takes the form of the gun wearing loose or the barrel wearing out. But they are designed to handle X rounds at standard pressures.

6) I see alot of folks calculate the strengths of Rugers, but these calculations are only ever performing an evaluation on a straight static pressure basis. This is wrong when trying to determine if a load is safe.

I attached a couple of marked up figures for your perusal


l0jSA85.jpg

Note the diagram shows that over pressure rounds will easily burst a Ruger cylinder after 650 rounds. We don't know the heat treatment that Ruger uses, if the cylinder is heat treated to a low hardness, then the lifetime of the cylinder will be longer, if pressures are low. If the cylinder is heat treated to a high hardness, then it will be strong, but its fatigue lifetime will be less. And I don't know if Ruger varies the heat treatment of its cylinders based on cartridge.
 
. . . will the brass show over pressure signs while the weapon is not considered over pressured? I guess I am asking will the brass only show signs of over pressure if the chamber is over pressured?
You have identified an interesting question: do the observations you use to "measurement pressure" correlate with pressure across the interesting range.

In modern (post-WWII) rifle cartridges, using rifle-ish burn rate powders, primer deformation correlates beautifully with pressure in the range of pressures near max design. That correlation doesn't exist ay very low pressures, for very high pressures, or for very fast burn-rate powders.

On the other hand, many pistol cartridges (45 Colt among them) operate at lower pressures, and I have not observed nearly so neat a correlation between charge approaching max and primer deformation. I would not rely on it.

The fundamental principal is:
- the measurement you're making is (almost) never measuring the dimension you are actually wanting. Almost all measurement methods are correlative measures, not direct. Pay careful attention to outside effects that might interrupt your correlation.
 
The yield strength of cartridge brass is over 20Kpsi, so pressure signs won't exist at the SAAMI pressure levels of some handgun cartridges.

Using chronograph velocities is crude as well if we lack measured velocity data with corresponding pressure data from our specific handgun. The best we can safely do is to stay within pressure tested recipies and approach the velocities of same bullet weight factory (pressure tested) ammo fired in our specific guns.

45 Colt "Ruger Only" loads are another subject since neither SAAMI nor Ruger has published any pressure limits or recommendations for such loads.
 
OP, I have an "old Vaquero" in .45 Colt that I would load a few "magnum but not maximum" loads for back when I also had a Uberti .45 Colt SAA clone.

I put an X in black sharpie on the case heads of the magnum loads so I knew right away that they do not go in the Uberti.

My "magnum" loads were somewhere in the 20,000 PSI range according to the various loading manuals I consulted. Since the standard Colt load runs at 14,000 PSI or thereabouts, this is a substantial increase. My loads used the 250 grain Hornady XTP MAG bullets, which were made for the increased velocities. I'm not going to post my load, as it worked in my gun, because it is overpressure and potentially unsafe for the unwary.

I am sure the Ruger could handle more pressure, but I'm not one to push limits or beat my stuff up. Besides, if I want more I'll grab a .44 Magnum or the .454 Super Redhawk out of the safe.

Here is a Chuck Hawks article on overpressure .45 Colt loads. https://www.chuckhawks.com/high-pressure45.htm

Good luck finding what you're looking for. Stay safe.
 
45 Colt "Ruger Only" loads are another subject since neither SAAMI nor Ruger has published any pressure limits or recommendations for such loads.

Besides, if I want more I'll grab a .44 Magnum or the .454 Super Redhawk

That's kind of my spin on it. It's nice to have the increased strength of a Ruger pistol to safely push .45 Colt loads, but I think the whole idea of Ruger-only loads is a tricky path, indeed.
 
Straight-walled revolver cartridges are not reliable indicators of pressure. Pressures as high as double the maximum pressure can be reached before pressure signs show up. Never exceed maximum book charges, and if you have a chronograph, never exceed published maximum velocities (in the same length barrel). Revolvers are not long range weapons, and adding another 100-150 fps will only increase range about 10 yards. The 45 Colt cartridge kills by penetration and blood loss, and high velocity is not needed to accomplish this.
 
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