signs of stress in 9 mmm para shells
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"Tino" rclaz...@hotmail.com
Hi, Ive just begun to handload my ammo and have a question or two.
What are the signs on a case that the load is to hot?
What happens with the pressure if I deviate from the suggested Min Case Overall Length?
(Is there a constant that follows, that the pressure will rise let say 30bar/0,1mm that I shorten the MCOL???) Any help is welcome.
-Tino
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bt ...@aol.com (Bterr)
Pressure signs on shell casings are very unreliable. When they show up, you're usually way over maximum. Reloading for some semi-autos is not recommended by the mfg., so contact the maker of your gun. It's best not to reload for semi-autos, but if you must, go with the most conservative loads in the book, because resizing does not restore strength to cases.
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Danno oleda...@hotmail.com
There is a lot of good reloading information on this site: http://stevespages.com/table3.html Danno
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"Jerry Houston" jerry.hous...@comcast.net
Given the number of semiautos used in serious competitive shooting, I'd guess that there are probably far more reloads fired in semis than in any other kind of firearm. A manufacturer may warn against using reloads, creating an additional product liability escape hatch, but in real life, I think you'll find that they're the only ones who believe "It's best not to reload for semi-autos." ...
# Pressure signs on shell casings are very unreliable. When they show up, you're # usually way over maximum. Reloading for some semi-autos is not recommended by # the mfg., so contact the maker of your gun. It's best not to reload for # semi-autos, but if you must, go with the most conservative loads in the book, # because resizing does not restore strength to cases.
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Sta ...@americanisp.net (Stan Schaefer)
Maybe Clark has done some destructo tests on bullet seating, he likes blowing up guns...
Stan
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chang pxcha...@hotmail.com
# Pressure signs on shell casings are very unreliable. When they show up, you're # usually way over maximum. Reloading for some semi-autos is not recommended by # the mfg., so contact the maker of your gun. It's best not to reload for # semi-autos, but if you must, go with the most conservative loads in the book, # because resizing does not restore strength to cases.
All manufacturers recommend against handloads, but mostly from a liability standpoint since they don't know what's being loaded.
Contacting one is futile since they'll recommend against using any handloads.
Many people who shot a lot run nothing but handloads through their guns, and I doubt that "the most conservative" loads are being used.
Anyone with common sense and the ability to read and count can reload rounds that are just as safe as factory rounds.
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Clark Magnuson c.magnu...@comcast.net
# # #What are the signs on a case that the load is to hot?
# The pressure signs I have seen in 9mm have different sequences depending on the gun, but within the sub sequence there is a certain order. For instance the Case support may be the limit in one gun with poor case support like a Glock, while the primer may be the limit in a gun with a large firing pin hole like a Kel-Tec, while the extractor groove of the br*** may be the limit in a gun like a Tokarev, and the chamber splitting may be the limit in a weak gun like a CZ52. Also slower powders are harder on the primer and faster powder are harder on the br*** as the flash hole acts as a delay line: Higher force extraction: 1) The case has a gilded look to the br*** from the high points of the micro ridges of the sides of the case being scraped.
2) The extractor mark on the rim gets deeper.
Primers: 1) flattening of the primer 2) Standard primers pierce 3) Magnum primers pierce Case support: 1) A bulge on the case in the shape of the feed ramp, 90 degrees from the extractor mark.
2) A hole blows in the case in the shape of the feed ramp.
3) The case head fails and there is a hole from the front of the feed ramp mark to the back of the case.
http://www.thehighroad.org/attachment.php?s=&postid=236652 Extractor cut: 1) The extractor groove shows a .001" increase in diameter from firing 2) The primer falls out http://www.thehighroad.org/attachment.php?s=&postid=49766 http://www.thehighroad.org/attachment.php?s=&postid=333274 http://www.thehighroad.org/attachment.php?s=&postid=398118 Gun failure: 1) The barrel may split # #What happens with the pressure if I deviate from the suggested Min Case #Overall Length?
#(Is there a constant that follows, that the pressure will rise let say #30bar/0,1mm that I shorten the MCOL???) # OAL and pressure: The SAAMI registered max pressures for 9mm Para [or 9mm Luger or 9x19mm] is 35, 000 psi and 38,000 psi for +P.
My Quickload program converts that to 2413 bar and 2620 bar respectively.
I f in Quickload I have a 125 gr. Sierra JHP bullet seated at 1.169" OAL and 7.34 gr. Power Pistol, the pressure is calculated at 38,046 psi [2623 bar].
If the OAL is reduced by .004 [~.1mm], then the pressure goes up to 38706 psi [2668 bar].
If I reduce the powder charge to 7.29 gr., then the pressure drops back down to 38031 psi [ 2622 bar] So I am getting 45 bar /.1mm in this one example calculation.
Reducing the OAL increases the expansion ratio and the pressure.
Both increase the efficiency.
# # #
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pokeee ...@yahoo.com
#What are the signs on a case that the load is to hot?
# The signs vary from one gun to the next and even in the same gun they will vary as the recoil spring ages and weakens. Basically, you need to start with a new recoil spring and some fairly hot factory loads.
Fire a bunch of the factory cartridges and measure the outside diameter of the fired case at several specific distances up from the base, for the lower half of the case. Then do the same for several of your handloads. Higher pressures result in more residual pressure as the case is initially backing out of the chamber during extraction, giving more case bulge. Of course, a weakening recoil spring will give you the same results.
With practice, you will be able to feel cases which have more bulge, when you resize them. If this occurs with a handload you have been using for a long time with no problems, it probably means you need to replace the recoil spring :-) Then again, though this works for my pistols, you may need to look for other signs with your guns <shrug> #What happens with the pressure if I deviate from the suggested Min Case #Overall Length?
Maybe nothing, maybe a catastrophic increase of pressure or maybe a decrease of pressure. It depends on the bullet length, shape of the bullet base and interior shape of the case. The critical factor here is the case volume with the bullet seated in the case. If you use a shorter bullet or one with a concave base, you will need to seat it to a shorter OAL just to avoid losing pressure and performance. If you use a longer bullet, you will need to seat it to a longer OAL to avoid a catastrophic pressure increase.
#(Is there a constant that follows, that the pressure will rise let say #30bar/0,1mm that I shorten the MCOL???) # No. The initial pressure from the primer firing determines the starting point on the pressure curve. The shape of the curve changes with that initial pressure, the type of powder, the inertia of the bullet, the hardness of the copper jacket, the thickness of the copper jacket, the height and width of the rifling lands, the actual bore measurement of the barrel, the tightness of the chamber... The list of variables goes on and on. As the curve changes, so will the location and height of the pressure peak.
Since case volume changes from lot to lot and manufacturer to manufacturer, you are best advised to use starting loads (which are intentionally mild) and slowly work your way to the performance you desire, monitoring bullet velocity and case bulge as you proceed. Of course, any time you use a different bullet or case, you need to start over.
Another factor that contributes to pressure, is how soft or hard the br*** is. Br*** which grips the bullet more tightly, gives you slightly higher initial pressure levels when the primer fires. This slight increase in pressure allows the powder to burn faster, resulting in more rapidly increasing pressure. The hardness of the br*** changes every time you fire and resize the case, giving you variations even within casings, which all came from the same lot. If you notice that it takes more pressure to seat some bullets, it would be a good idea to set those cartridges aside and fire them over the chronograph to see just how much more velocity the tighter cases are giving you. If the velocity is above the max for the load table and charge you were using, you need to reduce your charge or stop reloading those particular cases.
People who reload mixed cases, usually just use them for fairly mild target loads. That way a reduced volume case with work hardened br***, should only result in a hot load instead of a catastrophicly hot load.
regards, Joe It matters not how experienced you are, nor how dedicated to the task. If you're not having fun, you are doing it wrong.
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"Charles Winters" ch...@mindspring.com
T: Suggest you go easy on this one. The 9mm Para is a high pressure round to begin with and case signs are not reliable enough to keep you out of trouble. By trouble, I mean a split case with hot gas damaging your gun and tender flesh. The best approach is:
- Use a reloading manual as a guide, Lyman is best
- Avoid the max loads
- Use a chronograph to gauge pressure The method is to start with a bullet weight and powder from the manual. The load table will advise minimum and maximum charge weights and corresponding velocity. For heavier bullets and higher velocities, medium burning rate powders are better suited. For 124 grainers, I like Bluedot with mag primers.
For a given powder and bullet weight, pressure and velocity follow the same curve, or close enough. When the velocity approaches the maximum listed in the manual, its time to stop. The objective should be accuracy with adequate velocity, not maximum velocity just prior to blow up. Stick with the longest OAL your gun will reliably feed, typically about 1.12" in this round. - CW > ...
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colonelden ...@yahoo.com (Colonel Denier)
There are some common overpressure signs such as flattened, flowing, or cratered primers, flattened case heads, etc., but like others have said, these don't appear reliably, and often can be caused by other conditions.
Regarding case OAL, I would *surmise* that seating a little deeper than the min OAL would probably not cause catastrophic results in 9mm.
I would not want to try it with .40 S&W, though, as it's supposed to be very sensitive to seating depth. Still, I can't help but suspect that modern reloading manuals have a little bit of a safety margin built in for liability reasons.
At any rate, there is no good reason, as far as I'm concerned, with seating the bullet deeper than the minimum. In fact, I like to generally seat mine out as far as possible, as long as they will feed reliably.
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Alex Vitek alex...@ix.netcom.com
#Pressure signs on shell casings are very unreliable. When they show up, you're #usually way over maximum.
THis seems to hold for some handgun reloading applications. But, I see nothing wrong with adding the one additional sign of pressure and that is your own instincts. If you think there is something wrong with the load because it just does not feel right, well then, you are probably right.
#Reloading for some semi-autos is not recommended by #the mfg., so contact the maker of your gun.
Just about every handgun manufacturer out there will say not to use handloads in their guns. But, not all of them. The custom handgun builders will not only encourage handloads but will even go so far as to tell you the recipe to use to produce the ammo that they want you to use during the break in period.
Some of them will also build guns to make use of over normal pressure loads.
But, these are not for the everyday shooter. These are competition guns and are often built to the users specifications.
#It's best not to reload for #semi-autos, but if you must, go with the most conservative loads in the book, #because resizing does not restore strength to cases.
Shooting a reloaded case does tend to weaken the case. But, in handgun, these cases can last a long time going through many, many reloadings. I can get up to 10 to 15 magnum loadings out of a 357 Mag case and up to 40 if I keep the loads relatively mild. Chances are that I will never find out how many loadings a 45 ACP case will handle since I will loose the br*** faster than it weakens.
I have the feeling that most 9MM cases will handle many more reloadings than most of us think.
Alex Vitek <alex...@ix.netcom.com> ******** "The highest function of ecology is the understanding of the consequences." Pardot Kynes, Initial Report to the Imperium DUNE: HOUSE ATREIDES (Brian Herbert and Kevin J. Anderson) ********
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David Steuber david.steu...@verizon.net
# I have the feeling that most 9MM cases will handle many more # reloadings than most of us think.
***uming you don't loose them. I've loaded 9x19mm and .45 ACP.
Loosing the cases is by far my biggest problem. Revolvers are a real plus in this area. Heck, I couldn't afford to shoot .44 Mag without reloading for it. For the revolver, I just neck size. It seems the br*** does not expand to be larger than the chamber. Although it can start to get a little tight.
I'm not recommending anyone try this, but I've used more than the max load of power pistol with a small rifle primer in 9x19mm. R-P br*** is strong stuff. I suspect one of the earlier signs of over-pressure you will see is a catastrophic failure. That's ***uming you find a powder, bullet and gun combination that puts you that high.
--
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"Whoever is advising them [Democrats] on gun control should be shot." --- Blaine Rummel, spokesman for the Coalition to Stop Gun Violence
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