Light loads dangerous?

[Sarge]

Hey all,

I have read here and heard from other sources about too light of a load blowing a gun up. Can somebody please direct me to the source of this info.

I don't doubt it in the least I just want to know how it happens, what causes it ,etc.. From an unscientific point of view it makes sense that too heavy of a load could do it but not too light of one.

A good reference please? Thanks

[gm iprod]

I can only relate my own personel experience.

38Special. I have used 125gr Cast Lead for light loads using Win231 (3.0gr), Hodgdon TG (2.6gr) and Clays (2.6gr) and they all left the barrel and landed on target.

38Super. 100gr SWC Cast, 3.5gr TG as above. My daughter loved these in my iron sight gun.

303 British. 100gr Hornady 32cal pistol bullets, velocity about 1800fps, with H or IMR4227, can't remember the load, but it was 50% case capacity. OK to 50Y. Plus I load 215gr Lead over 8.5gr Vihtavouri N320. Subsonic and no recoil. Accurate at 100y. But crap thereafter.

Not one of these laods is better than 50% Load density and all work fine. The main issue is if you go too light you can get an incoplete burn and jam a projectile in the barrel. Then the next one does the firearm in.

A careful approach and awareness of what is happening will keep you safe.

[The_Vigilante]

Have heard and read that using W296 in quantity less than prescribed will cause this!

[JKSNIPER]

Without taking a long tme and more space than I want to the light load can POSSIBLY SOMETIMES create a huge spike in pressure.

Initially if the projectile does not leave the case from the expansion of the powder when it normally would in a regular load the pressure can spike up and it can happen here or when the projectile leaves the case and then "jumps" onto the lands and grooves of the barrel.

The projectile can be "jammed" at this point due to insufficient pressure and the delay in movement can cause a big spike in pressure.

To make it simple to explain I'll liken it to the force needed to push a stalled car.

Once the car is moving no sweat but if someone hits the brakes suddenly you have to push much harder to get it moving again.

Think of the bullet as the car and the sudden braking force as the bullet encountering the lands and grooves.

Hope this helps.

JK

[rhyrlik]

Personal experience:

148gr HBWC + 2 grains of Bullseye in a 357 case = Detonation + pierced primers.

[Sarge]

OK. So what I am seeing is light loads are potentially dangerous if they are crazy low. It looks like an auto would probably quit working right before any real dangers occur? IE FTE etc.

I had already assumed most of the situations posted, IE Not enough umph to get the bullet moving fast enough to clear the barrel fast enough or not clear it at all.

I don't intend to download this low. I had just thought about a light springed light load for club steel matches and did not want to blow my M&P apart. I am sure it will hover somewhere around just under minor pf. Heck I might not even mess with it. I am loading Titegroup.

[DonT]

FWIW, I'm using 3.3gr of Titegroup in my .40 minor load and I don't think I would go any lower. Getting unburnt powder flakes on my forearms when shooting.

[G-ManBart]

This all goes back to the old .38Spl wadcutter loads with 148gr bullets and something like 2.5gr of Bullseye. The theory (which has never been proven) is that the powder is lying all on the side of the case and it ignites all at once rather than a progressive burn. The guns invariably have burst cylinders (revolvers, of course) and often have the top strap bent/cracked/missing. The powder companies have tried to duplicate the pressures required to do such damage and they have...with double or triple charges, which would (conveniently) fit in a .38Spl case just fine. I don't believe they've ever documented a spike in pressure with extremely low charges like the one described above. Some folks still believe it, some folks don't, but I think more folks are leaning towards the idea that it's multiple charges rather than a freak ballistic event.

I'm not buying the concept of the bullet not leaving the case, then the pressure spikes or that it spikes when it jumps and engages the rifling. In pistol ammo the bullet always jumps to the rifling since we don't seat them out long enough to be very close or lightly touching the rifling as you might for a benchrest gun. Just the primer alone is normally enough to get the bullet out of the case and into the rifling.

[gm iprod]

G-manBart has got it.

I have deliberately loaded 9mm, 38Super and 38Special to such low levels that the firearm fails and sometime projectiles have lodged in barrela nd or throat. No signsof high pressure has been evident. A chemist I know who works alot with flammable liquids and gasses has a simple theory. Less fuel (propellant) = less pressure. He works in the Protroleum Industry and there main concern is fuel air mixes. He explains that seeing as we are dealing with a solid propellant that carries its own oxegen then the air inside the case can not provide enough oxygen to promote combustion to the level that will cause excessive pressure.

[robertbank]

Personal experience:

148gr HBWC + 2 grains of Bullseye in a 357 case = Detonation + pierced primers.

I have to call BS on this one. Take a look at the recommend loads for the .41LC using Bullseye. There has never been a labratory induced "detonation" ever. Not one. Go over to the Cast Bullet Forum if you want to find loads using reduced powder charges using cast bullets. 10 gr of Unique in rifle cases under lead bullets is almost a standard gallery load. 16 gr of 2400 in virutally any of the military cartridges is used regularly by cast shooters as a starting point for developing loads using cast bullets.

DonT - I shot over 5,000 rounds of 2.8 gr of Titegroup under my 180 gr lead bullets in .40cal. last year. Load makes minor PF for IPSC and IDPA . Load is soft shooting and entireingly safe.

I find it amazing that folks can feel safe to load near the maximum in their firearms but attribute almost mysterious qualities to a couple of flakes of powder if used by themselves.

Take Care

Bob

[Braxton1]

I wouldn't call BS on Bart for this one. Ask around at your local SASS club. There are tons of documented instances of light-loaded 45LC blowing guns up.

A lot of the Cowboys use tissue paper in their loads to keep the powder settled on the bottom of the case. Doing this, they can get away with powder puff loads, but if they don't, "BANGO!!!".

(Using an onomatopoeia on this site is sorta stupid, isn't it? It could start a thread over whether a cylinder rupture sounds like "Bango!" or "Pffffft".)

[BlackBuzzard]

A while back I asked what a minimum charge should be to get a bullet to just clear end of barrel......I got no answers.

So one boring day I loaded 0.9gn TG behind 180gn Berry plated 40SW and fired through a Glock 35 over a chrono. What do you think happened?

BB

Answer: Bullet traveled 1/2 inch into barrel and stopped.

Edited April 12, 2009 by BlackBuzzard

[David Sinko]

I am no fan of ridiculously light powder charges in pistol and revolver cartridges but I have shot the 100 gr. cast SWC out of both the .30-30 and .300 Savage using 7.5 grs. of 231. I do this quite frequently and it duplicates the ballistics of the .32 H&R Magnum quite nicely.

Dave Sinko

[rhyrlik]

Personal experience:

148gr HBWC + 2 grains of Bullseye in a 357 case = Detonation + pierced primers.

I have to call BS on this one. Take a look at the recommend loads for the .41LC using Bullseye. There has never been a labratory induced "detonation" ever. Not one. Go over to the Cast Bullet Forum if you want to find loads using reduced powder charges using cast bullets. 10 gr of Unique in rifle cases under lead bullets is almost a standard gallery load. 16 gr of 2400 in virutally any of the military cartridges is used regularly by cast shooters as a starting point for developing loads using cast bullets.

DonT - I shot over 5,000 rounds of 2.8 gr of Titegroup under my 180 gr lead bullets in .40cal. last year. Load makes minor PF for IPSC and IDPA . Load is soft shooting and entireingly safe.

I find it amazing that folks can feel safe to load near the maximum in their firearms but attribute almost mysterious qualities to a couple of flakes of powder if used by themselves.

Take Care

Bob

Let me explain something to you Bob,

I wanted to load some very light loads primarily to reduce noise as much as possible. I loaded a bunch of ammo from as light as 1.5 grains all the way to 3 grains of Bullseye. With loads at or below 2 grains, I experienced detonation. How? I don't know, but pierced primers and pristine cases that stuck in the chamber were suere signs of excessive pressures. How does one get excessive pressures with 1.5 gains of Bullseye in a 357 case, Bob? Please explain it to us. Please explain how such a load sticks in the chamber, how such a load seals the chamber so well that there is absolutely no soot, no carbon, no fouling at all on the outside of the case, how the report from such a load sounds like piercing noise instead of the typical bang? How about it, Bob? Every single round was loaded on a single stage press and checked. There were no triple or quadruple charges. How is it that when the powder charge exceeded two grains of Bullseye the gun started to sound normal, the primers stopped piercing, the cases stopped sticking, and ejected dirty? Please explain, Bob. Please explain it because you seem to know everything about internal ballistics, don't you, Bob.

[matt2ace]

I have to agree with Bart on this one. I had a discussion with a very experience commercial reloader about loading light 44 magnum loads and he warned me against it for just the same reason as the 38sp described by Bart. As he explained it, case volume is another factor in the dynamics of very light loads. 38/357, 44, and 45LC cases are relatively high volume which provides a lot of room for powder or a lot of space for pressure to build up. The idea that a low volume of powder in a high volume case burns very different is the likely reason for these blow-ups. 44 special cases are lower in volume for just this reason, to allow for a lighter load without risk of over-pressure.

For those running light 40 or 9mm loads, these cases are relatively short and low volume when compared to the calibers I cite above. Light loads in these cases still take up a reasonable precentage of overall case volume. These light loads burn much the same way as heavier loads which is why there is little concern for light loads in 9mm or 40.

Edited April 12, 2009 by matt2ace

[BlackBuzzard]

I have to agree with Bart on this one. I had a discussion with a very experience commercial reloader about loading light 44 magnum loads and he warned me against it for just the same reason as the 38sp described by Bart. As he explained it, case volume is another factor in the dynamics of very light loads. 38/357, 44, and 45LC cases are relatively high volume which provides a lot of room for powder or a lot of space for pressure to build up. The idea that a low volume of powder in a high volume case burns very different is the likely reason for these blow-ups. 44 special cases are lower in volume for just this reason, to allow for a lighter load without risk of over-pressure.

For those running light 40 or 9mm loads, these cases are relatively short and low volume when compared to the calibers I cite above. Light loads in these cases still take up a reasonable precentage of overall case volume. These light loads burn much the same way as heavier loads which is why there is little concern for light loads in 9mm or 40.

The above seems reasonable to me after reading it carefully.

But certainly there must be industry data and recommendations out there that cover this topic? I'd like to see it.

After all..... "modern" ammo development and refinement has been going on for over 100 years.

I just scanned my Speer Reloading handbook and TightGroup labels.......and nowhere is caution with minimal charges mentioned. But they do go to great lengths and caution regarding maximum loads etc, for obvious reasons.

BB

[dajarrel]

In his book, Understanding Firearm Ballistics, Robert A. Rinker addresses the subject of reduced loads:

"One unproven theory was used in a Kentucky court case. (Schuster v. Steedley, Oct. 1966, 406 W.W. sd 387.)

As related by an expert witness from H.P. White Laboratory, the theory stated that when a cartridge is loaded so that the powder charge leaves a lot of space in the cavity between the primer and the base of the bullet, the primer flash can cross the open space while the powder is laying on the bottom. (The cartridge being horizontal at the time.) This flash may move the bullet out of the case but it will have insufficient energy to properly engage the rifling. This will take place a short instant before the powder is ignited and creates the main gas expanding force. More force is then required to move the bullet than is normal and excessive pressure is exerted on the cartridge's base and the breech mechanism of the gun. Also, the bullet may become lodged in the barrel and create an obstruction for a successive shot.

Another theory that is about the same maintains that the powder may partially ignite and create a "slow burn." This propels the powder to the front where it presses against the bullet and can create a pressure wave cause by runaway burning."

Note that Mr. Rinker addresses these events as "theory." I'm not a ballistics expert nor did I stay in a Holiday Inn last night, but this excerpt supports what I have always held as true.

As for rhyrlik's post... I learned long time ago that I never argue with a man's personal experience. He was there, I wasn't.

I just happen to believe differently.

fwiw

dj

[Sarge]

Hey guys, except for the snide remarks by some this is exactly the kind of discussion I was hoping to get. I have never been fully capable of wrapping my mind around this issue but this is helping make sense of it all. Thanks as always

[JThompson]

One thing I didn't see here is the case of having a light load not burning all the powder because it's light. I know if I run something like Sil to low the powder doesn't ignite properly and leaves unburnt powder all over, including in the barrel... you get enough of that shit building up and I can see it going kaboom.

JT

[rhyrlik]

In his book, Understanding Firearm Ballistics, Robert A. Rinker addresses the subject of reduced loads:

"One unproven theory was used in a Kentucky court case. (Schuster v. Steedley, Oct. 1966, 406 W.W. sd 387.)

As related by an expert witness from H.P. White Laboratory, the theory stated that when a cartridge is loaded so that the powder charge leaves a lot of space in the cavity between the primer and the base of the bullet, the primer flash can cross the open space while the powder is laying on the bottom. (The cartridge being horizontal at the time.) This flash may move the bullet out of the case but it will have insufficient energy to properly engage the rifling. This will take place a short instant before the powder is ignited and creates the main gas expanding force. More force is then required to move the bullet than is normal and excessive pressure is exerted on the cartridge's base and the breech mechanism of the gun. Also, the bullet may become lodged in the barrel and create an obstruction for a successive shot.

Another theory that is about the same maintains that the powder may partially ignite and create a "slow burn." This propels the powder to the front where it presses against the bullet and can create a pressure wave cause by runaway burning."

Note that Mr. Rinker addresses these events as "theory." I'm not a ballistics expert nor did I stay in a Holiday Inn last night, but this excerpt supports what I have always held as true.

As for rhyrlik's post... I learned long time ago that I never argue with a man's personal experience. He was there, I wasn't.

I just happen to believe differently.

fwiw

dj

And another theory is that when all the powder is lying on the bottom of the case, the primer flash will ignite all the powder granules at once. The powder will not burn gradually. Instead, it will burn instantly and cause a pressure spike.

Ideally, you want a 100% load density so you have an actual powder column to ignite. Such a column will burn from the bottom to the top and the pressure will rise gradually. This simply is not possible with some target loads.

[oldtrooper]

I have shot thousands of rounds in 38 Spl cases using 148 gr. WC Hollow Base bullets seated flush over 2.7 gr Bullseye. No problems.

[G-ManBart]

And another theory is that when all the powder is lying on the bottom of the case, the primer flash will ignite all the powder granules at once. The powder will not burn gradually. Instead, it will burn instantly and cause a pressure spike.

The question I have (not pretending to be an expert, by any means, here) is why haven't the powder manufacturers ever been able to reproduce a detonation with a very light charge of fast powders? I know they've tried. I know they've documented problems with light loads of very slow powders (I think W296 is the one you see the most warnings about). Then they go and test multiple charges of those same powders and get the results people have described with exploding guns....makes me wonder. R,

[rhyrlik]

And another theory is that when all the powder is lying on the bottom of the case, the primer flash will ignite all the powder granules at once. The powder will not burn gradually. Instead, it will burn instantly and cause a pressure spike.

The question I have (not pretending to be an expert, by any means, here) is why haven't the powder manufacturers ever been able to reproduce a detonation with a very light charge of fast powders? I know they've tried. I know they've documented problems with light loads of very slow powders (I think W296 is the one you see the most warnings about). Then they go and test multiple charges of those same powders and get the results people have described with exploding guns....makes me wonder. R,

Why do Glocks explode with factory ammo on law enforcement ranges? God knows Glock and the ammo manufacturers have tried to simulate these KB's.

I don't think they tried to load a 500 FPS HBWC load in a 357 case, however. That's not something alot of people would be interested in. I think their experiments were taylored toward standard loads, not near-squibs.

[matt2ace]

I have to agree with Bart on this one. I had a discussion with a very experience commercial reloader about loading light 44 magnum loads and he warned me against it for just the same reason as the 38sp described by Bart. As he explained it, case volume is another factor in the dynamics of very light loads. 38/357, 44, and 45LC cases are relatively high volume which provides a lot of room for powder or a lot of space for pressure to build up. The idea that a low volume of powder in a high volume case burns very different is the likely reason for these blow-ups. 44 special cases are lower in volume for just this reason, to allow for a lighter load without risk of over-pressure.

For those running light 40 or 9mm loads, these cases are relatively short and low volume when compared to the calibers I cite above. Light loads in these cases still take up a reasonable precentage of overall case volume. These light loads burn much the same way as heavier loads which is why there is little concern for light loads in 9mm or 40.

Had another discussion on this topic with my friend....he added that the choice of powder is also a factor (density, burn-rate, etc.)

This is pretty complex when you think about it.

I am surprised that there is not more data from mfr or even in reloading books on this topic. Perhaps the lack of info is intentional, there may be liability issues involved in publishing data on very light loads.

[D. Manley]

Why do Glocks explode with factory ammo on law enforcement ranges? God knows Glock and the ammo manufacturers have tried to simulate these KB's.

I don't think they tried to load a 500 FPS HBWC load in a 357 case, however. That's not something alot of people would be interested in. I think their experiments were taylored toward standard loads, not near-squibs.

The cause of this has long since been identified as bullet setback due to frequent chamber cycling of defensive rounds. Most departments are now aware of the risks of repeated cycling and the problem has all but disappeared. I might add that just because its factory ammuntion it's a mistake to think the quality cannot be suspect. I have seen things come out of pristine factory ammo boxes that no self-respecting reloader would have cranked out much less, actually dared to fire.