.357 loads - pressure question

RickC · November 16, 1999, 09:58 PM

I have a favorite load for .357 that I have used for quite some time:

140gr LSWC over 15.3 gr Herc 2400 over CCI small magnum primer.

I have used this in my Colt Python, 6 inch barrel.

Here's the question: My Python was stolen during a break-in and I have replaced it with another Python, but the barrel length is 8".

Now I know this load is "hot", so I am concerned that the extra barrel length may just allow the pressure to rise enough more to cause problems.

Any opionions?

**Mal H** · November 16, 1999, 10:25 PM

RickC,
Agreed that 15.3 gr of 2400 for a 140 lead bullet is hot but not excessively so. It should be just as safe in the 8" Python as in the 6". The question of pressure really has little or nothing to do with barrel length. By the time the bullet gets to that extra 2" the pressure is way down. Think about it this way, if your theory was correct then we would have a lot of blown .357/.44/.45 rifles.

Now, all that being said, I would prefer to load a lighter round for the initial test if you have any thoughts that your loads are tickling the tail of the tiger. But don't forget that most folks test their new guns with high pressure factory rounds.

Cheapo · November 17, 1999, 01:36 AM

Hey, I tried working up some .357 loads about a year and a half ago using a powder which had no loading data. Did it by the book, started low using data from powders *close* in so-called burn rate, and all that.

Velocities were erratic all the way up to the last two or three test charges. Accuracy was always good but not great. Got reasonably close to my desired velocity with this neat low-flash powder.

Then I tried them in another 6-inch gun and a 4-inch. BOYOBOYOHBOY was I ever surprised! The old 4-inch was within 10-15 fps of what I was getting with my 6-inch. The newer 6-inch (L-frame Smith) was almost 200 fps faster than my 6-inch. And the pressure in the L-frame was clearly excessive! Flat primers, sticky/stuck cases and all that.

Turns out a previous load about .8 gr lower was okay in the highest-pressure gun I had tested. Then when the loading data finally came out for the .357 (there was TONS of semiauto data), even that load was about .4 above the recommended max.

Conclusion: don't be surprised if a load that appears safe in one firearm turns out to be seriously overpressure in another. If the "load to velocity" theory is true, that hot load was safe in only one of the three guns.

For that particular powder, it appears that it just doesn't work well at low loading densities, as found in the .357 Mag.

Reduce your load by about 10% and work it back up. As well-stated above, the extra 2 inches will NOT be the cause of any higher peak pressures. IIRC, revolver cartridges hit peak pressure somewhere in the first INCH of bullet travel. Then it's all downhill from there.

**Mal H** · November 17, 1999, 01:46 AM

Cheapo, your observations are right on target. When handloading it is always a wise practice to decrease loads at least 10% and work up from there whenever any component is changed. And the gun is certainly one of the components.

I should have pointed out that you will get higher velocity from the longer barrel, but it is not due to higher pressure. It is simply due to longer acceleration time for the bullet under pressure.

BenDover · November 17, 1999, 04:35 PM

I agree with above. Your pressure should not increase with barrel length. If it worked fine in your last snake, it should be the same in this one. Hope it helps...Steve

WESHOOT2 · November 17, 1999, 05:44 PM

SAFETY FIRST!

DECREASE your load before trying it in your new gun.

Personal experience has proven this multiple times; all guns are NOT created equal.

------------------
"All my ammo is factory ammo"

November 16, 1999, 09:58 PM	#1
RickC Member Join Date: October 20, 1999 Location: Ontario, Canada Posts: 68	I have a favorite load for .357 that I have used for quite some time: 140gr LSWC over 15.3 gr Herc 2400 over CCI small magnum primer. I have used this in my Colt Python, 6 inch barrel. Here's the question: My Python was stolen during a break-in and I have replaced it with another Python, but the barrel length is 8". Now I know this load is "hot", so I am concerned that the extra barrel length may just allow the pressure to rise enough more to cause problems. Any opionions?

November 16, 1999, 10:25 PM	#2
Mal H Staff Join Date: March 20, 1999 Location: Somewhere in the woods of Northern Virginia Posts: 16,955	RickC, Agreed that 15.3 gr of 2400 for a 140 lead bullet is hot but not excessively so. It should be just as safe in the 8" Python as in the 6". The question of pressure really has little or nothing to do with barrel length. By the time the bullet gets to that extra 2" the pressure is way down. Think about it this way, if your theory was correct then we would have a lot of blown .357/.44/.45 rifles. Now, all that being said, I would prefer to load a lighter round for the initial test if you have any thoughts that your loads are tickling the tail of the tiger. But don't forget that most folks test their new guns with high pressure factory rounds.

November 17, 1999, 01:36 AM	#3
Cheapo Senior Member Join Date: November 19, 1998 Posts: 986	Hey, I tried working up some .357 loads about a year and a half ago using a powder which had no loading data. Did it by the book, started low using data from powders close in so-called burn rate, and all that. Velocities were erratic all the way up to the last two or three test charges. Accuracy was always good but not great. Got reasonably close to my desired velocity with this neat low-flash powder. Then I tried them in another 6-inch gun and a 4-inch. BOYOBOYOHBOY was I ever surprised! The old 4-inch was within 10-15 fps of what I was getting with my 6-inch. The newer 6-inch (L-frame Smith) was almost 200 fps faster than my 6-inch. And the pressure in the L-frame was clearly excessive! Flat primers, sticky/stuck cases and all that. Turns out a previous load about .8 gr lower was okay in the highest-pressure gun I had tested. Then when the loading data finally came out for the .357 (there was TONS of semiauto data), even that load was about .4 above the recommended max. Conclusion: don't be surprised if a load that appears safe in one firearm turns out to be seriously overpressure in another. If the "load to velocity" theory is true, that hot load was safe in only one of the three guns. For that particular powder, it appears that it just doesn't work well at low loading densities, as found in the .357 Mag. Reduce your load by about 10% and work it back up. As well-stated above, the extra 2 inches will NOT be the cause of any higher peak pressures. IIRC, revolver cartridges hit peak pressure somewhere in the first INCH of bullet travel. Then it's all downhill from there.

November 17, 1999, 01:46 AM	#4
Mal H Staff Join Date: March 20, 1999 Location: Somewhere in the woods of Northern Virginia Posts: 16,955	Cheapo, your observations are right on target. When handloading it is always a wise practice to decrease loads at least 10% and work up from there whenever any component is changed. And the gun is certainly one of the components. I should have pointed out that you will get higher velocity from the longer barrel, but it is not due to higher pressure. It is simply due to longer acceleration time for the bullet under pressure.

November 17, 1999, 04:35 PM	#5
BenDover Member Join Date: October 14, 1999 Location: San Diego, CA. USA Posts: 51	I agree with above. Your pressure should not increase with barrel length. If it worked fine in your last snake, it should be the same in this one. Hope it helps...Steve

November 17, 1999, 05:44 PM	#6
WESHOOT2 Senior Member Join Date: February 20, 1999 Location: home on the range; Vermont (Caspian country) Posts: 14,324	SAFETY FIRST! DECREASE your load before trying it in your new gun. Personal experience has proven this multiple times; all guns are NOT created equal. ------------------ "All my ammo is factory ammo"