Is severe underloading an issue?

If I drive 10 percent slower than the minimum posted speed limit I get a fine - I get the minimum thing, so I have no excuse. Yet we have people so shook up by the "It's dangerous crowd" that they scour the load manuals for the lightest posted loads and reduce it further to be "safer", and it's not.

I can't be sure that SEE exists or doesn't, but after a few hangfires with light loads of slow(er) powders like H4350, my light and cast loads are all now with much faster powders.

By far the most common causes of "kabooms" are bore obstructions and massive overloads. There's no sure way to know what happened here, but it was almost certainly negligence of some sort.
 
Mycroft said:
Actually, it is what led to the only accident (in 75 years) at the range I frequent.

One of the members had a underpowered reload and the blowback blew apart the breech and sent the bolt flying and severed his thumb. You can still the mark in the wooden overhang where it impacted.

Be careful.
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Sounds like this is related to advice an old timer gave me back in the 70's when I was in my teens. During my first reloading session he was reloading 6mm rem explaining max and minimum loads. He described a 30-06 failure at Silverdale where the breach failed and the bolt exploded back out of the gun. The correct powder was used but less than a minimum load was used. He told me there was not enough pressure to expand the case and grip the insides of the chamber causing the base of the case to strike back against the bolt face causing the catastrophic failure. Since that time I have read about this effect where this type of failure can occur because of loading below the recommended minimum safe load
 
B said:
SEE in small arms cartridges is a myth and IMO a scapegoat for people who fucc
up and can't admit it. If you disagree go tell the technicians at Speer/ATK/CCI they are wrong. Most likely cause is wrong powder or a lodged bullet as has been mentioned several times.
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SEE has been reproduced in Norma's lab.

But yeah, there is no way to know what actually happened here.
 
Andy said:
Yet we have people so shook up by the "It's dangerous crowd" that they scour the load manuals for the lightest posted loads and reduce it further to be "safer", and it's not.

Andy, this statement is soooooooo true, the same ones that think the rifle will blow up if you exceed some arbitrary, lawyer approved loading manual by 1/2 a grain.

Pathfinder, is there a report on the reproduced Norma event? I would really love to read it, this has been one of my pet research topics in the gun/handloading world. I read the article in this months Handloader, although informative, it lacked substance. Possibly something lost in translation.
I have a theory about how it happens but not the balls anymore to attempt a reproduction, now 20 years ago............I believe ambient temp has a great effect on the possibility of getting a SEE and from all that I've read temp has never been factored in. Very interested in Normas parameters and findings.
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c-fbmi said:
Andy said:
Yet we have people so shook up by the "It's dangerous crowd" that they scour the load manuals for the lightest posted loads and reduce it further to be "safer", and it's not.

Andy, this statement is soooooooo true, the same ones that think the rifle will blow up if you exceed some arbitrary, lawyer approved loading manual by 1/2 a grain.

Pathfinder, is there a report on the reproduced Norma event? I would really love to read it, this has been one of my pet research topics in the gun/handloading world. I read the article in this months Handloader, although informative, it lacked substance. Possibly something lost in translation.
I have a theory about how it happens but not the balls anymore to attempt a reproduction, now 20 years ago............I believe ambient temp has a great effect on the possibility of getting a SEE and from all that I've read temp has never been factored in. Very interested in Normas parameters and findings.
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Ive never been able to get my hands on a report. There was a mention of it in one of PO Ackley Books but ive never had any specific Parameters. Baribal would be able to tell you and he's also had some first hand experience with it also.
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Year ago I read about loads starting at the low end and using 4831.
It was suggested that with the barrel pointed down, then raised to a firing position, the powder was such that a "flashover" occurred.
Pressures increased rapidly causing rifles to fail.
If not mistaken, Jack O'Connor may have had something to do with the article.
 
Thanks guys. I suspect you are correct in that the powder detonated vs burning. (an SEE event)

I am positive it was not a barrel obstruction, wrong powder etc issue.

Thanks again
 
B said:
SEE in small arms cartridges is a myth and IMO a scapegoat for people who fucc
up and can't admit it. If you disagree go tell the technicians at Speer/ATK/CCI they are wrong. Most likely cause is wrong powder or a lodged bullet as has been mentioned several times.
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First one to get it correct!
 
Bigbubba said:
Ok so today I saw a bolt action rifle (6mm I think) that had a big chunk of the stock missing between the trigger guard and the bolt, the stock was cracked on the opposite side, there was a split in the receiver across the top just behind the chamber.

The shooter was there, he was giving the rifle to a guy to use in his safety training class. He got a concussion when the incident occurred.

He said he was new to rifle reloading (but experienced pistol loader) and the data he had said to start at 10% LESS than the MINIMUM load. (not 10% < max) So he is 100% sure he started at 10% < Min load. I have never seen any data that said that.

Assuming that he did that, has anyone ever heard of such a light load causing such catastrophic failure?
Thanks for your input
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I've heard of it, when I was researching reloading for the first time , I can't remember exactly how it was explained but it happens.
 
Got curious on the result of that study again and reached out to Norma to see if I can get some eyes on the documentation. I too am interested in the parameters that they would have used.
 
Here's what says Norma about SEE (but they don't call it that way);

Hazard of Too Little Powder
It is obvious to every experienced handloader that it is important not to use too heavy a propellant charge in any given load. However many handloaders do not realize how critical it can be to use too light a propellant charge. This is a particularly critical consideration when using any slow-burning powder. Owing to heavy surface treatment, with inert (deterrent) chemicals that is necessary to slow initial combus¬tion, these powder types are harder to ignite. Generally, the "slower" the powder, the harder it is to ignite. Norma MRP and MRP2 (and similar propellant types from other vendors) fall into this category.

Should the handloader use too light a charge with such a propellant, ineffective ignition can occur. With such a small charge, much primer energy is wasted moving the charge and much primer heat are wasted heating the exposed case interior. As a result, the primer blast might only ignite a small percentage of the powder granules. The granules that are ignited can generate sufficient propellant gas to move the bullet only a few inches.

Because only a small percentage of the charge is ignited, relatively little gas is generated. Hence, as the bullet begins to move into the bore, pressure (and temperature) within the propellant plume decreases rapidly. As a result, the bullet slows and can even stop. In such a load, granules that the primer did not directly ignite do not ignite rapidly (before the buffet moves significantly), as would happen in any normal loading.

Cooling of the propellant cloud allows partially-reacted propellant gases to begin to condense onto the relatively cold, unignited propellant granules. This initiates a chain reaction: Condensation converts gas to a liquid, which dramatically reduces pressure (and temperature) inside the case, this results in even faster condensation, which results in an even more rapid decrease in temperature; once this process begins, almost instantly, chamber pressure drops to almost nothing and the bullet rapidly slows or stops.

Equally, this condensation rapidly transfers hem to the surface of the remaining granules. Since the preceding primer blast and ignition of some granules will have significantly heated those granules (often to nearly ignition temperature) and because some or ail the deterred surface may have burned away from many of the remaining granules (contrary to intuition, sufficiently rapid cooling can "put out" an ignited granule), subsequent ignition and combustion of remaining granules occurs extremely rapidly. The entire remaining charge, which is now located as a single lump directly behind the buffet, can hum before the buffet can move significantly.

As was first studied and proven by the Krupp Commission, circa 1888, whenever the ignited charge is located at one end of a relatively empty chamber (as in this instance). combustion generates a "standing wave" within the combustion chamber. This occurs because, as the charge burns, an initial pressure wave moves toward and reflects from the case head interior surface. Meanwhile, gas flow and changing pressure within the buffet end of the chamber can oppose the progress of the reflected wave. This can
Slow, stop or even reverse the direction of this pressure wave. Whenever this happens, pressure near the peak continues to increase - Las molecules continue to enter this zone (from both sides) faster than molecules leave it; all else being equal, the more molecules are in any given volume of gas the higher the pressure!
In the above situation, average chamber pressure will, no doubt, remain relatively low - often it will never reach normal peak chamber pressure; however, pressure near the peak of the "standing wave" can be several times as great as normal maximum chamber pressure! It is well proven that such a situation can wreck even the soundest gun. The resulting explosion can be lethal.

Generally, the bigger the case, the slower the propellant, and the colder the ambient temperature, the more likely this result is to occur.

CAUTION: Never use charges lighter than the suggested starting charge, as listed in a reputable, modern handloading manual.

NORMA - RELOADING MANUAL 2004 149
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Believe or not, they told me they can reproduce it almost at will.

They began their trials / studies when they started to load for then coming M/41 round (so, well before 1941) and saw it occuring with their (then new) slower powders. P.O. Ackley also produced it, but he was much less successful in reproducing it. They worked together (Norma and Ackley) to define what / how it happens and when.
 
I researched SEE's a while ago out of curiosity and most everyone said it's impossible to determine if there is a standing wave inside the case or not due to the limitations of detection methods with current technology. I wonder what technique lead them in 1888 to conclude it was a standing wave?

I've loaded many hundred rounds with light loads over the past few years using slow powders (like H4831) and have noticed that sometimes not all the powder burns. Many times I have been left with blackened but otherwise seemingly unburnt granules of powder in the throat and bore of the rifle. Never had any signs of spikes in pressure from it though.
 
Well, Internet is Internet... there are a lot of unprovable "theories" and "experts" on every subject you want. On the other hand, you have the ones who can reference it... in this case, I can't say Norma is a not a reliable source of information... well, like religion, it's to each his own faith.
 
I've seen the results of a light load in a 308. Gun show reloads in $1000 Sako caused the barrel to cartwheel downrange! Then, his buddy chambered a round from the same lot into his 700 and locked it up tight. Saw the powder charge in one of the loads after the Sako owner came back screaming faulty firearm. We pulled the bullet and what we figure was less than a 50% charge of a cylindrical powder followed. Sako laughed, 700 did get going again. I'm no expert, but careful reloading is a must!
 
if you underload enough the powder will lay flat along the case and not fill it. when the primer goes off it will set all the powder off at once instead of a steady burn from bottom to top of the shell which will blow the chamber and top of the barrel off if you are unlucky. can stop this by filling the case the rest of the way with cornmeal or some other wadding.

the other issue would be a load that does not push the bullet out of the barrel. which causes another set of problems.
 
Logic. It's not for everyone...
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These days it seems logic is not for most people.


Don't all primers detonate all powders?
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Smokeless powder does not detonate. It deflagrates which is just a high falutin' word for "burns". Detonation requires a shockwave front which is something that does not occur in smokeless powder under normal conditions.
 
Suputin said:
These days it seems logic is not for most people.




Smokeless powder does not detonate. It deflagrates which is just a high falutin' word for "burns". Detonation requires a shockwave front which is something that does not occur in smokeless powder under normal conditions.
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X2......Thanks you beat me to it.......................
 
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