How much pressure


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Jesse Heywood
December 4, 2010, 09:55 PM
I screwed up a load in 357 magnum. Only thing I can determine is that some idiot :banghead: used a jacketed load for lead. Loaded July 3, so maybe I was ready for fireworks.

Load was 7.7 gr. Green Dot, 158 gr. LSWC (MBC 357 Action), Federal SP match primers, 1.607 OAL, heavy roll crimp in resized mixed brass. DO NOT USE THIS LOAD. I had started at 6.5 gr. with moderate to heavy recoil. The 7.7 gr. load flattened, but did not pierce the primers. Gun is a Colt Trooper MK III, 6" that was new to me.

Can someone run this in Quickload and tell me what kind of pressure I had. Lee shows 34,000 PSI with 6.0 gr. Green Dot with this bullet. I am curios about the pressure, and certainly don't want to repeat and have to post in the dumbest reloading mistakes thread.

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GLOOB
December 5, 2010, 01:36 AM
I thought lead bullets produce less pressure from a given load. What pressures are the jacketed bullets supposed to run at?

padd54
December 5, 2010, 01:51 AM
Here is what I got from Quickload;

pressure = 50195
MV = 1311

A wee bit on the warm side.

Clark
December 5, 2010, 04:40 AM
Quickload thinks that some of my 9mm loads are over 1,000,000 psi and over 2,000 fps.

But the primers do not pierce and the bullets don't go that fast over the chrono.

The makers of Quickload warn that straight wall cartridges can blow powder out the muzzle or burn it, and they calculate worst case.

What does it all mean?
1) Don't trust a QL prediction on pressure unless the chrono data matches the QL velocity prediction.
2) A 357 mag case with 50kpsi should have sticky extraction, and prediction is likely an exaggeration.

243winxb
December 5, 2010, 10:21 AM
Alliant Reloaders Guide 1999 for 357mag. lists 6.0gr-Green Dot 158gr lswc-1240 fps- 34,000 PSI . Old Speer #8 lists 6.5gr-1144fps Maximum.NOTE that Speers loads are over maximum pressures for the most part. IMO.:uhoh: A 357 mag case with 50kpsi should have sticky extraction, and prediction is likely an exaggeration.
Yes, very sticky, like needing to drive the case out of the cylinder with a steel rod.

243winxb
December 5, 2010, 10:49 AM
I thought lead bullets produce less pressure from a given load. What pressures are the jacketed bullets supposed to run at? Saami lists the 357 mag @ 35,000 PSI. (may have changed) lead or J, dont matter to the gun. Alliant shows for a jacketed bullet- 158gr-7.0 Green Dot-1215fps-34,000 PSI Maximum. There are no general rules. Each caliber can/may act differently, pressure wise, with a given powder. Green Dot Powder is a poor choice for the 357 mag to reach maximum fps. IMO :uhoh:

Jesse Heywood
December 5, 2010, 02:07 PM
The cases weren't stuck in the cylinder, but they didn't fall out, either.

Green Dot Powder is a poor choice for the 357 mag to reach maximum fps. IMO
Please explain. Green dot is one of my favorites. I've had excellent results with 45 Colt. And with this 357 load I had good accuracy in spite of the recoil.

Thanks to all for the input.

243winxb
December 5, 2010, 02:23 PM
Slower burning rates of powder make less pressure then Green Dot if your loading to get maximum velocity. Example- Alliant data with a 158gr lswc- 15.3gr-2400 powder maximum 1620 fps- 34,000 PSI You get over 400fps more at the same pressue using 2400. At least on paper.:scrutiny: I load 14.0 gr of 2400 158gr lswc cast and get 1254 fps- 6" revolver. If your loading works safely for you, thats fine.

Mal H
December 5, 2010, 03:12 PM
As mentioned above 7.7 grains of Green Dot is too hot for a 158 gr lead bullet. You may not visibly damage your revolver (such as an extremely rapid disassembly), but you could loosen it up a bit more than you should in its short life to this point.

How many rounds have you shot, and how many unfired rounds do you have remaining?

Jesse Heywood
December 5, 2010, 06:09 PM
I misunderstood what 243winxb was saying. Thought he was saying Green Dot wasn't a good choice at the higher end of the recommended loads. In this case Lee shows to be 5.4 to 6.0 gr. I am not trying for hot loads with Green Dot, 2400 or 4227 are better choices for that. So far I like Green Dot and am satisfied with the results obtained.

Somewhere along the line I misread a page in Waters manual, and loaded lead bullets with the powder charge for jacketed. When I stepped up to the 7.7 gr. load I could tell the previous charge was hotter than expected. Primers were okay and the cases didn't stick, but the recoil was heavy. So I inserted one cartridge of the 7.7 gr. and fired. The case wasn't stuck and didn't take much force to eject, but it didn't fall out like most. The primer was flat, but not pierced. And the remaining rounds have been dismantled and all components recycled.

My question about the pressure was not for the purpose of trying to exceed the proper load, but curiosity about how much pressure I had subjected the gun to. From quickload data provided by padd54 of 50,000 psi I feel that I didn't damage the gun. I certainly would not want to fire a box at that pressure.

The bit about Speer loads being over pressure is why I no longer use their manuals.

Clark
December 8, 2010, 06:39 AM
rec.guns post from 1993 by John Bercovitz about when cases stick in a 357 mag (http://groups.google.com/group/rec.guns/browse_frm/thread/68ca10110c80e7aa/f002ce69fa01e631)
The model 27 has thick
chamber walls and the model 19 has thin chamber walls. Cartridge cases
which contained full-pressure loads are easily extracted from a model 27
but they have to be pounded out of a model 19. So manufacturers don't
manufacture full-pressure loads for the 357 magnums anymore. 8-(

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