A Puzzling occurence

[kickinback]

To clarify, I think you had an obstruction in the barrel.

[Camel]

I did think of that Glen, but discounted it because I think there would probably have been a big difference between the shot in question and the next one. The pressure would have been greater and the case would have formed better than it did. I haven't had a barrel obstruction so don't know what it would be like. That nicely formed dent in the case has me very very intrigued.

Flip, when you were loading them, did you complete them one at a time, or did you put the powder in them all and then seat the projectiles, Do you use a reloading block and by chance just miss putting the powder in one case. I cant help but think this way, as is think the case would have been fully formed if there had been anything other than no powder. Although I cant for the life of me think what would cause that dent in the shoulder, the primer popping is another puzzler.

[Flip]

Kickinback, the shot before hilled a fox at 115 or so meters by the range finder.

Camel,
They were loaded one at at time. as in all cases are in a home made loading block that I made, I keep all case apart from the one to be charged up side down so as not to inadvertenly spill powder in to an empty shell. I charge the shell with a load then set a nothe charge in the pan on the scales while this is settling I seat a projectile in the case just charged with powder and check the length of the case and projectile.

Hope this helps

Cheers guys

Flip

[kickinback]

I'm sticking with barrel obstruction Mark. Bullet stops on barrel and turns it into a pressure vessel. Gas punches out primer and pushes it up against the firing pin hole blocking the gas escaping down there resulting in the case head expanding. Powder continues to burn. Gasses find a path down beside the neck and punch in the shoulder causing the dent. Pressure is equalised around the case and has built to the required level to expel both projectile and whatever was blocking the barrel.

Just my theory.

[Camel]

Rito Flip that seems to have got that out of the way, sounds very much like I do and its pretty hard to stuff things up that way.

Glen, you may very well be correct, but wouldn't it then form the shoulder properly if there was enough pressure to blow the primer. If there was a blockage, would there be some sort of pressure wave coming back down the barrel forcing the case backwards and that caused the shoulder to get rounded and dented ? What ever caused it, it certainly is an intriguing little mystery.

[bimbo]

All I can think of is that the case shoulder was slightly too short and hasnt sealed in the chamber allowing gas/pressure to go past the neck causing that dent. Not sure how that would effect the primer and buldging case head though

[Camel]

I was wondering if there was a 222 case that had been necked down in there somehow, but don't think that would happen it would stick out like dogs balls when loading, so discounted the idea.

[bimbo]

Similar makr/dent to
http://www.ar15.com/archive/topic.html? ... 2&t=350529

[Flip]

Cheers bimbo,

That seems to be it dosnt it.

AR2208 is on the slower side. and I'm using 25 grn pills.

These cases are new, so not sized to the chamber as I neck size only once fired.

the case is very clean around the neck area and there is a very slight discoloration in the dent.

So it could be partly S.E.S with the expanded head maybey and blowen primer pocket..................?? and escaping gases causing the Dent. The only answer really is a light powder charge it seems.

people have been using AR 2208 for years so it must be a combination of a couple of small thing with this rifle and that load. Clutching at straws a bit I know


SO IT WAS ME !!!

Valuable Lesson learnt.

Thanks All very much

Flip

[Glenn]

Sorry Camel,

What i meant to say was that the shoulder is now rounded out slightly not a straight angle as with a regular case.

could be an under load but it sounded normal to me. was not a squib or primer only.

not fire forming. brass was brand new first loading.

I'm trying to get some picks atm.

Flip

When you fire new brass in your gun you ARE fire forming to your chamber!

I hear a lot of people say they don't want an AI case because they have to fireform?
You do even if it isn't a AI chamber.

A crush fit is what you are after when you are fire forming, a pound of pressure on the bolt when you close the bolt.
Adjust your neck die to achieve the above crush.

From what the link said it looks like a low charge but it could of been a combination of the above and charge.

Glenn

[Flip]

Point taken Glenn and thanks.

That makes perfect sense. that brass is not fire formed to that chamber and if that chamber is on the larger side of the scale more than likely contributed to the issue with slightly under sized brass in a slightly lager chamber possibly.

If I got that wrong please let me know

cheers

Flip

[Glenn]

Exactly Flip!

Glenn

[stinkitup]

When you say light powder charge does it still fill the case or leave it quite empty.

S.E.S Secondary Explosion ....?

I had a secondary explosion event with my 6.5x55 and 2209 not enough powder in a fireformed case, as it was a military chamber they are on the larger side, locked it up but no dent like that case of yours, wood block to open the bolt and primer popped out once we got it opened. Bent the bolt but with a little heat it is back to normal, the old mans welding technique must have been pretty good

Reading later usually slower powders with heavy projectiles cause the SEE I had, from that AR15 forum sounds like too low a pressure.

These anomalies can make loading disconcerting.

[Flip]

Thanks Kickin,

The bolt was certainly not that hard to lift.


I got that from uncle Nick's book I think....... I Could very well be wrong but, S.E.S Secondary Explosion Syndrome ? I belive it was refered to.

Cheers

Flip

[chris.tyne]

Can anyone say "secondary explosion",read up on that one.