.38 Special 147 grain +p+

Handy: I agree, in fact, if you look at my original post, it says...

It is definitely so that certain manufacturers manage to get considerably more velocity out of the same gun (say 10%), while staying under the same pressure limit.
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The way that this might be done is by controlling the dynamics of the burn process (essentially combustion rate over time) to avoid very high peak pressures, while maintaining good oomph all the way down the barrel.
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...which is the same thing that you are saying. Also, I didn't say that velocity is proportional to pressure, I said that force is proportional to pressure.

The reason that I kept posting is that JC disagrees with my point that bullet velocity and chamber/barrel pressure are closely related. The reason that's true is:

force on bullet = pressure * area [area of projection of bullet onto long axis]
bullet acceleration = force on bullet / bullet mass

The point that the bullet is accelerated over some time, during which the force varies is duely noted by me in my first post. I also note, though, that in practice, this doesn't greatly affect the outcome. Yes, I realize that you can construct the most extreme example possible to make it look more important than it is.

In other words, the first order way of looking at it is that velocities are monotonically increasing with chamber pressures. That's not an absolute relationship, but I think it's extremely useful to have an approximate view which captures the most important aspects of the situation. Just my opinion. :)
 
JC:
You're too heavy on theory and too light on practice.
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Maybe my verbage in the second post is a little tortured, but actually, I am exactly arguing for looking at what is most important in practice.

To choose another example, if we were talking about cars, and 1/4 mile speed in a drag race, I'd say, just look at the engine torque - that tells you what you need to know.

Now, you can always pick at that by saying, wait a minute, what if the tires slip? and how is the torque actually expressed over the duration of the run (over a spectrum of rpms)... and that's true, those effects modify the fundamental relationship. However, my point is, the fundamental relationship is that torque determines acceleration - and it's proper (in my mind) to consider first and recognize what is most important in practice. Doing so doesn't deny the existance of the wrinkles in the basic theory, it just puts things into their proper perspective.
 
After reading your response to Handy, I think we may are roughly saying the same but going about it differently--i.e., seeing the same thing at but at very different angles.

Rather than look at cars, a more telling example might be to look at the .45 ACP and the .45 GAP. Both deliver the same bullet (whether 185, 200 or 230 grains) at roughly the same velocity, BUT the .45 GAP requires approximately 10% more chamber pressure than the .45 ACP to achieve that velocity. (Now, there is a good reason why it requires more chamber pressure to achieve the velocity, but the point remains that difference in chamber pressure between the .45 ACP and the .45 GAP is roughly equivalent to the difference between standard pressure and +P pressure yet there is no difference in velocity.)

Again, my major difference was with vanfunk's assertion that you can estimate chamber pressure by comparing velocity (which implies a direct proportional relationship). It was not with you, and the esoterics of chamber pressure versus velocity.
 
Juliet charley, I think you like to argue with me ;) . I still don't think that a good condition Model 10 would be unsafe if six of theses rounds were fired from it (or even one box for that matter). As to police carrying .38's in the 60's and 70's, There were few hollowpoints around back then, and a FMJ or even softpoint .357 is likely to overpenetrate. I believe that this was based on sounder logic than political correctness. These rounds were made more recently than the 60's or 70's and I'd venture to guess that the only reason for this practice to continue into the 80's and 90's is for those who are recoil sensitive and if they're as powerful as you let on, then I doubt that they're low recoil so carrying them instead of .357 would be self-defeating. Once again note I did advise against routinely firing these (I advise against routinely firing +p ammo in anything for that matter) so if my advice is followed, I don't think that the revolver will go out of time or split a forcing cone. This is not a flame, just a respectful disagreement.
 
No, chances are a half dozen, or even a half dozen boxes, wouldn't make any difference, but I tend to fire my carry ammo a little more frequently than that. If your practice is to buy a box of fifty and make it last five years, you should be OK.

Actually, during the 70s and well into the 80s, the .38 Special 158-grain +P LSWCHP (FBI load) and the .357 Magnum 125-grain SJHPs were both well-established (and relatively "standard" law enforcment rounds). In that era, it was common practice to buy .357 Magnum handguns and carry the FBI load. Even in the heyday of the .357 Magnum and the 125-grain SJHPs, there were far more LEOs carrying .38 Specials (and quite often in revolvers chambered for the .357 Magnum). Even though the term "political correctness" was not in use in that era, there was a stigma attached to the .357 Magnum and quite often police administrators/city managers/boards/etc. dictated the carry of .38 Special ammunition (even though the handguns might well be chambered for the .357 Magnum). The good news is the FBI load was a very effective LE chambering (and in many ways, its good points outweighed those of the .357 Magnum 125-grain SJHPs--despite revisionist gunhack hype). That's the way it was--you are mistakenly assuming there's always logic in decisions made LE administrators.
 
Touche`, I forgot my own adage in regards to Law enforcement decisions: Common Sense isn't nearly as common as it should be.
 
Whew! It looks like I started somtin' fierce.

The +P or +P+ refers to chamber pressure NOT muzzle velocity--you cannot judge if a round is "too hot" by looking at the MV. There are number of good reasons (and I'd guess in the case of 147-grain +P+, flash suppressants) that chamber pressure may increase with little or no effect on MV. It is ver foolish to assume just because the MVs are the chamber pressure is close (and that is a recipe for a damaged weapon).
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I'm aware of this, which is why I said it "seemed" fine for any .38, and then asked if anyone knew what the max pressure was. I guess I should have fleshed out my question a little more.

Thanks,
vanfunk
 
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