Can it be the bullets?

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Tod may have been a victim of S.E.E. Secondary Explosion Effect. The believed causes are [this is the short version], The bullet is started out of the case down the barrel increasing the combustion chamber faster than the powder is producing gas [almost always happens with slow powders], thus dropping the pressure behind the bullet causing it to STOP in the barrel. The powder continues to deflagrate [burn] increasing pressure. The STOPPED bullet acts as a bore obstruction pressure increases to the point of action failure. In all cases I have heard of the bullet was pushed out of the barrel, usually with no signs of bore damage.
Contributing factors seem to be slow burning powders, the bullet starting down the barrel quickly and easily[no crimp, loose necks etc] and something that causes the bullet to stop [rough throat or leade, a bullet that may fit the bore too tight etc.]. When these strange set of events all come together at the same time....KABOOM.

Talk about your worst nightmare.

I'm not sure there's enough evidence left for most of us to answer this definitively, including me. It would be interesting to know the length of the obstruction in the barrel (my bet is one, not two bullet lengths),and the neck wall thickness at the BOTTOM of the neck. A .308 Norma Mag. case is .1" shorter at the top of the shoulder than a .300 Win. Mag. case, so if you run a .300 Win. Mag. case through a .308 Norma Mag. resizing die and then trim it to the length specification, some of the shoulder of the .300 Win. Mag. case ends up in the neck of the .308 Norma Mag. case and the neck wall thickness is (maybe) too great at the bottom of the neck. The case could then be too tight to let go of the bullet upon firing, and bam, the pressure goes through the roof, even with a starting load, and the case head lets go.

The light charge of slow burning powder is suspect, but likely not the cause.

Because the rifle has previously been safely fired, probably the chamber is okay, and we can rule out failure of the case because the belt recess was cut too deep by running the reamer in too far?

S.E.E. is normaly associated with small charges of slow burning powders, not case-full charges.
It normaly rears it's ugly head when your trying to do squib loads. IE: bringing a 300mag down to 30-30 levels for low recoil plinking/new shooter training.

blahhh

At the moment the barrel has not been cut open to examine the obstruction. Jack Belk is trying to get the rifle to examine it. Some suspects are Hawk bullets, an overload with the wrong powder, double base powders, excessive headspace, another belted magnum head separation and some others.

The obvious one to me is that a bore obstruction has been reported. That must be cut out and examined.

Good work Detectives

Hey Todd how are you doing now? Eyes all back up to speed?

Eye is alright, still can't see though. Hopefully time will heal.

Tod,

Your eyesight is of primary importance. I am not sure what the health care is in Canada but if it's compromised in the slightest by the way it's administered then go to the best place in the world for it.

On the accident. It seems that there may be a liablitity on the part of someone other than you. I would consult with an attorney and only have someone else hear about the details or see the gun with your lawyers approval.

In other words don't give anymore details here about the accident except we all want to stay up to date on how your eye is coming along.

I may have the wrong "read" on this but after looking at the posts on the other Boards it looks like (without all the facts) a combination
of a poorly 'smithed (bad chamber) rifle in the hands of inexperienced loaders/shooters who didn't understand the warning signs the rifle had previously exhibited before the catastrophic event.

It's always unfortunate when things like this happen but the rifle appeared to give them plenty of early warning something was wrong. Hopefully the shooter will fully recover and all can learn from the incident.

I am also very interested in such Blow-up's, since I tend to push the envelope on a regular basis with some very potent cannons!.. A few weeks ago we had a report of a new .405 winchester that apparantly was blown by using cartridges which were overly long for the chamber. Since Todd indicates that he trimmed the cases properly, this seems unlikely. Todd also appears to be a reasonably astute reloader, so I doubt the wrong powder/switched powder scenario was to blame.However, another likely cause is that the case necks were too tight. I've never tried to make a .308 Norma Mag from a 300 win mag, but I would be very concerned about the neck wall thickness. It's interesting that the chamber was marked as to length and not the neck diameter. I wonder exactly what the chamber dimensions were. A chamber cast may be of value assuming the chamber is still intact. Who built the gun and are his reamer specs still available? I have quite a bit of experience with tight necked benchrest guns and when forming brass from one caliber to another, the neck walls often have to be inside and outside reamed. You must have a minimum of .002 clearance.If this was not done, then you can put together a load that may chamber just fine, but the brass is unable to release the bullet. the case head will fail and the bullet will be found in the bore somewhere. In some extreme designs like the 220 swift brass actually flows under pressure into the neck area and leads to sporatic high pressure phenomenon unless carefully watched for. This is my bet. A chamber cast and pulling some of the loaded bullets will either confirm or eliminate my diagnosis.-Rob

Head dia 300 win mag is .532" 308 norma is .530". Belt dia 300 win mag is .513" 308 norma is .512". Could these small differences be a contributing factor? I wonder...

DB Bill & Robgunbuilder seem to be on the right track.

My dad bought the rifle in the '60's at a hardware store, who knows what monkey put it together.

I'm not going to get an attorney, go after who? Who's liable? If anybody is at fault, it's me for not realizing a potentially dangerous condition.

I hope to send it off to J Belk, if I can get it across the border with no trouble.

Robgunbuilder,


Tight case necks are a real possibility.
A chamber cast will tell that, as well as measuring some necks of my brass. When just sticking a Hawk bullet into a case, just to see what it looks like, it seemed almost 'oversize'. I tried this in fired brass from a 30-06 & a 300 WSM. Seemed to go in 'tight', even in fired cases. I know Hawk bullets are supposed to 'seal the bore', with their jacket material, just seems like they may be .3085" or so. This was the 1st time they were ever shot in the 308 Norma, shot 20 or so in a 30-06 with no problems.

TB

Hey Todd, ask the CFC if a blown up gun still qualifies as needing a registration certificate. It's always good to send them mail anyway, keeps them occupied, wouldn't want them to get bored would we?
I think you might want to check with American customs about importing a firearm into the USA as well. They have tightenned up considerably since 911.
Is that your shooting eye?

Todd.....if you're looking at improper bullet release (or restricted bullet release) causing the problem I think there are 3 things to consider....(1) brass that might be too long for the chamber; (2) excessive neck thickness either because of a flaw in the brass or brass flowing to the neck from firing; or (3) necks that have become excessive hard due to being reloaded too many times without being annealed....this can give you very erratic neck tension.

Todd- if you can't literally drop a bullet down into a fired case, then I think that the case neck is way too thick or tight!, the bullet oversize, or the chamber neck way too tight! Personally I believe all three factors are in play here. Do a chamber cast and see what that chamber actually is. Then measure the neck OD of a case and with a thickness micrometer take 5 readings of the case wall thickness and avg them. The bullet diameter .3085 plus two times the case wall thickness should add up to a value that is not less than .002 of the chamber neck dimension. If it's the same or larger you have your answer. Also pull some bullets and look for a "dougnut" in the case neck. A tight neck chamber should have at least .002 clearance between the chamber neck dimension and the loaded case neck OD. If even this much clearance doesn't allow the bullet to be easily released from the case, you have a bomb! This combined with a bullet design like the HAWK that is supposed to "bump up" easily to bore diameter is my guess at what caused the Kaboom! Let me know if I'm right!
Never, Never trust a chamber of any gun you ever buy! Particularily one chambered for a wildcat or rebarreled to another caliber. Factory or not!Always make a cerrosafe chamber cast
and measure it carefully. This may sound anal, but thank god you didn't get killed!

I hope I understand this situation. As I read Tod cannot see at all out of his right eye. If this is correct I don't think this is a casual situation.

I would take the strongest action possible on more than one front. The primary one of course is medical.

John Y Cannuck

I was thinking of trying to get a hold of them. It was registered, has the sticker serial number under the action. It was my shooting eye. I can shoot lefty too, and it may be a more dominant eye, so I'm not out of business. If I have to shoot left though, I will have to buy lefty guns, sell my righty's,(except Ruger No1).

DB Bill

I trim all my cases after sizing them. Always. #2 & #3 could be right.

Robgunbuilder

You know your stuff. I don;t have the tools to do any of that stuff. As I said before, I hope to send it to a good gunsmith, he will look at it.

Savage 99

I can see more out of my right eye everyday. I can see enough right now that I can almost make out your name in Bold on the computer screen at 20". Time should heal this wound.

That sounds like good news Todd, sure glad to hear it. GWS

WARNING.

Please go to Huntamerica.com - Rifles and Gunsmithing - Guess what my dad did....
and read the latest.

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[ 01-25-2003, 22:58: Message edited by: Savage99 ]

I think:

Neck wall was too thick; case wouldn't let go of bullet, pressure blew core through bullet and core halfway down bore, and head off case into belt recess cut too deep. The same thing will happen with an oversize bullet, i.e., a .338 in a .308 bore. The other cases that have been examined are too tight at the bottom of the neck, just as you would expect with .308 Norma Mag. brass made from .300 Win. Mag. brass without turning or reaming the necks to .308 Norma Mag specification.

Look at the March-April 2001 edition of Rifle Magazine for a report of a nearly identical blowup, p.10.