Question on reduced loads on a 223

Unclenick, I was using Labradar. Yeah, it was a joke. But you and I been shooting for many years. you dont see SD under 1 in strings but super rarely, if ever, because this is an AR15, not a bolt gun.
 
In my bolt guns, I have a "mid range" target load of a 50 gr. Sierra SP over 14 grs. of 2400. Velocity about 2200 and very accurate. I shoot steel to 200 yards with that load. In my knockabout Handi rifle, I load 45 gr sps over 6 grs of universal. It is my ".22 mag." load. And very accurate. All rifles mentioned are 1:12 twist barrels.
 
Unclenick said:
You have to distinguish between NO evidence and NO evidence you've run into. There is in fact a description of a blown-up 308 Win rifle that nearly cost the shooter his eyesight that was loaded with just 3.1 grains of N320 described on the Finnish Gunwriter's site. Dr. Lloyd Brownell reported measuring low charges very occasionally doubling normal full-load peak pressure in his laboratory measurements of the 30-06 at the U. of Michigan. He pointed out the problem with studying the phenomenon is statistical. The extreme pressure events are very low probability outliers for the pressure fluctuations produced by loads below about 40% case fill, so an awful lot of firing usually has to be done to run into one such event. But it isn't something that never happens. This more recent Master's thesis by an explosives engineering student mentions an explanation on page 30 having to do with combustible vapors from powder accumulating and then igniting. Detonation of explosive gases is not unusual. In engines, we call it knocking.
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The "description" of the .308 is speculative, at best. I have in fact seen the the Master's thesis you mentioned as well. The description on page 30 is merely a recitation of the prior theories. He did no testing and did not independently verify the theory. As such, still a theory that has never been proven. Research the back story of where this theory originated. No one with actual professional experience and knowledge gives quarter to the theory. Does the "theory" still exist? Yes, but based on the body of evidence, as a ballistics expert, I have seen it not allowed in court due to it being "junk science."

My Master's work was on IC engines. Knocking is not even close to the supposed low charge detonation theory. :eek:
 
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One of my reasons for getting a K-Hornet was because of the low amount of powder it uses. It has 2/3s the power of a .223 for 1/3 of the powder.

I found a Hornet load in an old book with 3.5g of Unique behind a 40g bullet. I shot a bunch of those before I had the barrel replaced (long story about the barrel and all in another thread.) I'm looking forward to getting out and shooting more of them. I only mention this because one of the reduced .223 loads was very similar...

Tony
 
MarkCO said:
The "description" of the .308 is speculative, at best.
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It's anecdotal reporting, and it's an interesting anecdote because a simple double charge (or even a quintuple overcharge) can't explain it, as it does with "Bullseye surprise" detonation claims in 38 Special in the past. And the anecdotal nature is what Dr. Brownell's point was. Most descriptions of gun bursts by light loads will be uncommon anecdotes because the event's statistical probability is so tiny. You can't generate statistical outliers on demand, which makes laboratory study problematic. But the probability isn't zero. So a declaration that it is entirely an old wive's tale is what strikes me as speculative. In fact, it is exactly the position taken in a Handloading article that Dr. Brownell was arguing against in a letter to the editor. I will see if I can find it and make it available to you.

As to the gas theory, I stated it is "an explanation" when I referred to it, just because the fact there is an explanation floating around in the world of explosives suggests the event had occurred enough to need explaining. I'd read somewhere previously that knocking resulted from fuel/air mix detonation, but a review of current descriptive articles have detonation separated out as autoignition (though I assume it would make a knocking sound when it occurs). So that was my bad.

A gas detonation would be slow compared to the detonation of a solid explosive, but could it initiate detonation in a hot fused powder mass? It would be interesting to explore. If you convert the potential energy in a fused powder mass (as you sometimes dig out of a case after a squib-out experience) to pressure, you get values local to the detonation front of about half a million psi. That would exist very briefly but would be enough to initiate cracking in steel.
 
I ignored Marko some time ago.
I HAVE loaded cast bullets in .223, don't have my data at this computer, but I did it, shot out of a BREN 805, with decent results. The 55gr BATOR bullet showed some serious promise, but I moved back to jacketed bullet loads when primers got scarce.
 
I simply do not believe in like 3.1 grains of N320 blowing up a rifle. I don't believe it so much, because it simply cannot be demonstrated, or repeated. So there is no point in ever even saying a low charge like that "can" blow up a rifle. I would say, that if somebody thinks a super low charge like that can blow up a rifle, I got some Bigfoot photo's, and they are real.

I would like to talk about my bigfoot photos.

But sorry, I can't replicated my photo's, I cant seem to find him again:( LOL
 
As far back as the 70s I can remember hearing about how too low a powder charge could cause a detonation.

It was always an uber rare event, and when it happened, it only happened with serious underloads of slow rifle powder in large magnum cases.

Not sure what has changed, but that was the days before the Internet....

From what I read nowdays, I get the impression that some people think if they deviate from published data in the tiniest amount their gun will blow up, they will be eaten by dragons and their children will die starving and alone to the 3rd generation because of their folly... :rolleyes:

Generally speaking, when I want a lighter load, I use a smaller round. I have guns in .22LR, .22WMR, .221 Fireball, .222 Rem, .223 Rem, and .22-250. One of those covers everything I might want to do with a .22 cal rifle.

I have created and used reduced loads in a number of cartridges but I won't give my loads here because they are well outside published data.

But do consider this, I do have published data for .223 in the 1900-2000fps range with 45-50gr bullets. Its in my old Lyman book, and its for cast bullets.

These level loads will also work with jacketed bullets. BUT you won't find them listed in the jacketed bullet section. The reason isn't because they won't work, or because they are dangerous, the reason is simply SPACE (and money).

Reloading manuals do not, and cannot list every possible combination. The list where the focus of the majority of shooter expect. People shooting jacketed bullets are looking for high performance loads (high velocity). So that's what the manuals test and list. This doesn't mean light loads don't exist, it just means they aren't listed in the majority of data.

For example, you can load a .44 Magnum to 850fps, but you wont find that load listed in the .44Mag data in any common reloading manual, simply because so few people are interested in it.

There were bullets in the past like the Speer 1/2 jacket (or 3/4 jacket) pistol bullets that needed a minimum velocity to prevent the jacket stripping off, but those slugs are uncommon today (though they did work well and I still have some ;)) Shooting a modern jacketed rifle bullet designed to work at 3000fps and slow speeds of 2000fps or so is unlikely to cause problems, though it will likely affect the expansion of the bullet.

An alternate path to light loads is a chamber adapter. I don't know if you can still get them but in the past you could get a chamber adapter to fire .22LR in .222, .223, etc. You could even get ones to shoot .32acp in some .30 cal rifles. Slow and cumbersome,single shot only, but they did work. Accuracy varied according to reports, and you weren't going to win any matches using one,but it did let you pop that gopher in the backyard without using a 3000fps+ varmint round and telling everyone in a 2 mile radius you were doing it.....;)
 
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