The UK's Finest Independent Forum for Shooters and Gun Owners. Est 2010.

Pete wrote:
I'd say a 223 is just as capable as any other calibre of falling apart if overloaded.

Pete

I have seen two 223s blow up and subsequent investigation showed both were caused by 'half-charges', with most powders the 223 is a compressed load or close to it so an over charge is less of an issue compared to under charge. One by a piece of the powder bottle sealer partially blocking the powder funnel and the other we think was caused by 'bridging of the powder in a Dillon powder measure (a known issue with some powders).

The only other one I know details of, the guy was reducing charges to try and get a subsonic load until it went bang.

In all instances the rifles (all AR derivatives) survived but needed some work to remove the brass. One broken bolt and carrier, two destroyed magazines and three red faces.

Lucky the faces were just red and not in tatters..........

Pete

A testament to the rugged design of the rifle design that is based on the AR - the bolt locking in to the barrel is what undoubtedly saved them all from some serious hurt.

Could someone explain why a half charge caused the .223's to blow up please?
Would this still happen with a bolt action?

I am only surmising as I don't know about the incident in question but it could be what is called secondary explosion effect.

This happens with reduced loads of medium to slow burning rifle powders which ha loading density that allows the primer to flash over the powder pushing the bullet into the rifling and stopping, the powder then burns, builds up pressure but the bullet has now become an obstruction and pressures can rise to catastrophic levels.

That is why you should never go below 60% loading density with medium to slow rifle powders, if you are looking for reduced loads then fast rifle and pistol powders are the way to go as they combust instantly at low loading densities.

Flash-over, or secondary explosion effect (SEE) as I've heard it called. This is what we thought happened in two of the cases (and most likely in the third as well).

Recovered, unfired cases, when weighed showed that some were noticeably lighter and when these were pulled had (where I still have data to hand) approximately 50% powder, averaging 12.5gn of the usual 23.8gn. The guy lightening his loads had lighter charges by design and the final one found the powder seal in the powder measure after returning home probably had lighter loads as well, although I have no info on the charges of any unfired rounds.

In this case it would have happened in whatever firearm it was fired in, bolt-gun, semi-auto or straight-pull, etc. Whether a weaker design would have contained the effect as well as the AR design is questionable.

I had a 223 browning x bolt explode in my face, subsequent investigations led to the probable cause being an under charged load of h335. Split the stock, destroyed the mag, scope and my hearing. Thankfully I was wearing Shooting specs, half the extractor was embedded in the lense.

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I know a chap who had a 7.62 explode with low power reloads. From memory, it was something like 11gn of Unique, and he had fired hundreds of this recipe over a long period before the incident. Low power loads can be dangerous, when I experimented with low power for my .308 I used published recipes for Trailboss - a low power but bulky powder.

Sounds more like a double charge reloading error, low density fast pistol to fast rifle powders are quiet safe. See Mattern, Harris and Brownell.

Also a search on here will reveal much that dispels the low charge with fast powders SEE myth.

Perpetuating the myth without substance helps no one.

dromia wrote:Sounds more like a double charge reloading error, low density fast pistol to fast rifle powders are quiet safe. See Mattern, Harris and Brownell.

Also a search on here will reveal much that dispels the low charge with fast powders SEE myth.

Perpetuating the myth without substance helps no one.

Point taken, I apologise if I have caused confusion, although perhaps my story illustrates the dangers of tiny charges in big cases being difficult to see - even for a very experienced loader who has loaded everything up to his .50 . I don't know whether 22gn of Unique would blow up a 7.62, I suppose it might with a heavy bullet.


As I wrote - Trailboss is my choice, nice and bulky.