Detonation, the dangerous effects of too little powder in large cases?

TVDean · March 31, 2001, 03:25 PM

Is this a worry?

I've been loading reduced velocity 10MM loads with fast powder (Titegroup) for lower power factors to better compete in USPSA's Production Class competitions.

It seems the worry of reduced powder charges is that more surface area of the powder is exposed to the primers ignition sparks. This could cause a larger than normal amount of the powder to instantly ignite and result in a catastrophic pressure spike.

Any more info besides this link would be appreciated.

http://www.reloadammo.com/liteload.htm

Thanks.

Cheapo · April 10, 2001, 11:31 AM

It's a shame that this thread died in the file corruption disaster.

Does anyone recall whether the research into the 2.8-gr of bullseye under 148-gr WCs in .38 Special problem included testing double- and triple-charges? IIRC, the Smith & Weasel K-frames fired the double-charges with no problem, and would only occasionally blow up with triple charges.

I STRONGLY hesitate to blame all "detonations" with light loads on double-charging. This was happening before the days of widespread use of progressive loaders. The procedure was to charge an entire loading block of cases, inspect them for high and low powder levels (easy to detect, with a whole field of powder charges to compare with), and only then would the hobbyist proceed to the bullet seating operation.

And unlike the overblown concerns from the .40 S&W and .357 SIG worlds regarding bullet seating depth, the .38 Specials involved were always seated either 1/16 or so out from the case mouth, or flush with the case mouth. No handling or feeding issues could result in a large reduction of internal powder space. And the blowups occurred with both HB and FB or double-ended bullets.

So, with the exception of light loads of Unique behind heavy bullets in large caliber rifles resulting in occasional "ring" bulges in the chambers ('nother topic entirely), I believe this light powder charge issue is still NOT understood at all.

Even though it has not been replicated in controlled conditions, it is reported often enough that I would avoid tiny charges in huge airspaces. I doubt that the 10mm would have a huge airspace like old blackpowder cases would.

Cheapo · April 10, 2001, 11:44 AM

I wrote this:

"And unlike the overblown concerns from the .40 S&W and .357 SIG worlds regarding bullet seating depth, "

Because the alarming pressure numbers in an American Handgunner article on bullet seating depth were the product of running a COMPUTER PROGRAM, not the results of actual testing and measurement.

Even though the methods were more purely scientific than stuff like "power factor," the fact remains that most mathematical models fall apart when you get too far from the "normal" ranges of values involved. Remember the "power factor" figures for a slow-moving bowling ball???

Southla1 · April 10, 2001, 12:00 PM

The procedure was to charge an entire loading block of cases, inspect them for high and low powder levels (easy to detect, with a whole field of powder charges to compare with), and only then would the hobbyist proceed to the bullet seating operation. I am one that still uses the old single stage press and a loading block. I load 100 at a time of .38 Spl's with either 2.7 or 3.0 grains of bullseye and a 148 grain WC. I have purposely thrown double charges to see how they look in the case compared to a single charge. It shows up like a sore thumb! I have yet to have a double charge or a detonation in 37 years of using this load. I find it hard to believe that a charge of 2.5 to 2.7 grains of bullseye is not ignited instantaneously because it does not nearly fill the case and even a small pistol primer had a hellofa wallop.

Art Eatman · April 10, 2001, 03:13 PM

My purely personal opinion is that any pistol blowup is from a double charge, not a too-light charge. The pressure levels are just too low, generally, at "normal" charge.

The ONLY blowup I have seen reported was a long time ago in the American Rifleman, for a .243 loaded down and with 3031. I disremember; 20 grains or 25 grains of charge.

SFAIK, in pistols, the only "too low" a powder charge would be one which fails to get the bullet completely out of the barrel.

Art

WESHOOT2 · April 11, 2001, 06:35 AM

At the time of the "Bullseye blow-up" Hercules engineers determined that was simply not enough energy in a 5.4g (double-charged) load to destroy a gun.

Best theory was bullet setback, which (screw AR, actual pressure data acquired) CAN increase pressure in both 40 S&W and 45ACP cases to over 100,000PSI.
I suggest well-used 38 Special cases with light or no crimp were a more likely culprit.

Think about that the next time you use marginal cases....case neck tension, our friend....

CapeFear · April 11, 2001, 06:52 AM

Deleted

[Edited by CapeFear on 04-11-2001 at 04:34 PM]

Clark · April 13, 2001, 09:54 PM

Opinions on detonation are worthless except when backed up with data.

Ron Reiber, balastician for Hodgdon said, "I have never been able to reproduce this condition in the lab with a rifle with a new barrel, but I have been able to do it with a barrel chambered for an over-bore cartridge that has a rough throat, like, say, a .243 Winchester that has been fired 500 times. You need both the recuced amount of slow-burning powder and a rough bore to make it happen, and that combination can raise pressure so high it will lock a rifle bolt shut."

Remember, for reduced loads, use a faster powder. Your accuracy will benefit, as those verticle strings with reduced loads of slow powders are mini detonations.

April 11, 2001, 06:35 AM	#6
WESHOOT2 Senior Member Join Date: February 20, 1999 Location: home on the range; Vermont (Caspian country) Posts: 14,324	At the time of the "Bullseye blow-up" Hercules engineers determined that was simply not enough energy in a 5.4g (double-charged) load to destroy a gun. Best theory was bullet setback, which (screw AR, actual pressure data acquired) CAN increase pressure in both 40 S&W and 45ACP cases to over 100,000PSI. I suggest well-used 38 Special cases with light or no crimp were a more likely culprit. Think about that the next time you use marginal cases....case neck tension, our friend.... __________________ . "all my ammo is mostly retired factory ammo"

March 31, 2001, 03:25 PM	#1
TVDean Senior Member Join Date: July 15, 1999 Posts: 173	Is this a worry? I've been loading reduced velocity 10MM loads with fast powder (Titegroup) for lower power factors to better compete in USPSA's Production Class competitions. It seems the worry of reduced powder charges is that more surface area of the powder is exposed to the primers ignition sparks. This could cause a larger than normal amount of the powder to instantly ignite and result in a catastrophic pressure spike. Any more info besides this link would be appreciated. http://www.reloadammo.com/liteload.htm Thanks.

April 10, 2001, 11:31 AM	#2
Cheapo Senior Member Join Date: November 19, 1998 Posts: 986	It's a shame that this thread died in the file corruption disaster. Does anyone recall whether the research into the 2.8-gr of bullseye under 148-gr WCs in .38 Special problem included testing double- and triple-charges? IIRC, the Smith & Weasel K-frames fired the double-charges with no problem, and would only occasionally blow up with triple charges. I STRONGLY hesitate to blame all "detonations" with light loads on double-charging. This was happening before the days of widespread use of progressive loaders. The procedure was to charge an entire loading block of cases, inspect them for high and low powder levels (easy to detect, with a whole field of powder charges to compare with), and only then would the hobbyist proceed to the bullet seating operation. And unlike the overblown concerns from the .40 S&W and .357 SIG worlds regarding bullet seating depth, the .38 Specials involved were always seated either 1/16 or so out from the case mouth, or flush with the case mouth. No handling or feeding issues could result in a large reduction of internal powder space. And the blowups occurred with both HB and FB or double-ended bullets. So, with the exception of light loads of Unique behind heavy bullets in large caliber rifles resulting in occasional "ring" bulges in the chambers ('nother topic entirely), I believe this light powder charge issue is still NOT understood at all. Even though it has not been replicated in controlled conditions, it is reported often enough that I would avoid tiny charges in huge airspaces. I doubt that the 10mm would have a huge airspace like old blackpowder cases would.

April 10, 2001, 11:44 AM	#3
Cheapo Senior Member Join Date: November 19, 1998 Posts: 986	I wrote this: "And unlike the overblown concerns from the .40 S&W and .357 SIG worlds regarding bullet seating depth, " Because the alarming pressure numbers in an American Handgunner article on bullet seating depth were the product of running a COMPUTER PROGRAM, not the results of actual testing and measurement. Even though the methods were more purely scientific than stuff like "power factor," the fact remains that most mathematical models fall apart when you get too far from the "normal" ranges of values involved. Remember the "power factor" figures for a slow-moving bowling ball???

April 10, 2001, 12:00 PM	#4
Southla1 Member In Memoriam Join Date: March 19, 2000 Location: Jeanerette, La. Near the Posts: 1,999	The procedure was to charge an entire loading block of cases, inspect them for high and low powder levels (easy to detect, with a whole field of powder charges to compare with), and only then would the hobbyist proceed to the bullet seating operation. I am one that still uses the old single stage press and a loading block. I load 100 at a time of .38 Spl's with either 2.7 or 3.0 grains of bullseye and a 148 grain WC. I have purposely thrown double charges to see how they look in the case compared to a single charge. It shows up like a sore thumb! I have yet to have a double charge or a detonation in 37 years of using this load. I find it hard to believe that a charge of 2.5 to 2.7 grains of bullseye is not ignited instantaneously because it does not nearly fill the case and even a small pistol primer had a hellofa wallop.

April 10, 2001, 03:13 PM	#5
Art Eatman Staff in Memoriam Join Date: November 13, 1998 Location: Terlingua, TX; Thomasville, GA Posts: 24,798	My purely personal opinion is that any pistol blowup is from a double charge, not a too-light charge. The pressure levels are just too low, generally, at "normal" charge. The ONLY blowup I have seen reported was a long time ago in the American Rifleman, for a .243 loaded down and with 3031. I disremember; 20 grains or 25 grains of charge. SFAIK, in pistols, the only "too low" a powder charge would be one which fails to get the bullet completely out of the barrel. Art

April 11, 2001, 06:52 AM	#7
CapeFear Member Join Date: April 8, 1999 Posts: 92	Deleted [Edited by CapeFear on 04-11-2001 at 04:34 PM]

April 13, 2001, 09:54 PM	#8
Clark Senior Member Join Date: December 4, 1999 Location: WA, the ever blue state Posts: 4,678	Opinions on detonation are worthless except when backed up with data. Ron Reiber, balastician for Hodgdon said, "I have never been able to reproduce this condition in the lab with a rifle with a new barrel, but I have been able to do it with a barrel chambered for an over-bore cartridge that has a rough throat, like, say, a .243 Winchester that has been fired 500 times. You need both the recuced amount of slow-burning powder and a rough bore to make it happen, and that combination can raise pressure so high it will lock a rifle bolt shut." Remember, for reduced loads, use a faster powder. Your accuracy will benefit, as those verticle strings with reduced loads of slow powders are mini detonations.