Is this safe??? Hurry before I blow myself up...

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I just had a new rifle built in .300 Win A.I. and my new chamber is .077 shorter than the factory .300 Win was. The old chamber was 2.955 from the head of the case to the ogive where it meets the rifling. The new chamber measures 2.878 to the ogive. I have a bunch of old reloads that I want to use to break my barrel in with and the bullets were seated to an overall length of 2.950 to the ogive. I just finished seating these a little deeper to the overall lenth (to the ogive) of 2.868 which should be .010 off the rifling. I do not remember what load was used with these reloads. In your opinion (no, I won't hold you to it[;)]), am I safe to fire these in my new rifle. I cannot see why not, but something is bugging me about it...Thanks for the feedback!

Eric
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mbsams

You're good to go for one! then look at your pressure signs - primer - bolt lift - extraction - extractor marks on head - case head expansion - after examination - you decide what to do.

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quote:Originally posted by mbsams
You're good to go for one! then look at your pressure signs - primer - bolt lift - extraction - extractor marks on head - case head expansion - after examination - you decide what to do.


Well, I did not blow myself up, but there were some pressure signs...and I'm not sure why but this thing kicked a lot more than a .300 Win...the Jewel trigger even cut my finger. The primer filled the pocket and there is a ridge around the firing pin crater. The line where the neck transitions to the shoulder was cracked half way around the case, with two splits half way up the neck on either side of the shoulder crack. There was also a slight shiny ring near the head of the case. Guess I'll have to pull these bullets...

Eric
allamericanarmsco@frontiernet.net

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JustC

the bright shiny ring is a STOP SIGN. Pull them down[8] How many firings on these cases? remember if they are work hardened and you are trying to fireform these for your AI chamber, they can and will crack. Also,..when forming an AI case with a bullet,..it is very important to jamm the bullet into the lands quite well and force the casehead back against the boltface to compress the extractor. That will allow the forming of the shoulder and taper reduction to get it's brass from the neck area and NOT from the casehead area.

a few questions

did the fired cases have a .002-.003" crush fit against the AI chamber datum line when chambered?

Does new brass have the .002-.003" crush fit when chambered?

If not,..then here is the sequence of events. First, by not jamming the pill against the lands and compressing the ejector spring, you will have some "extra" headspace due to the chamber NOT beign cut for the correct fit of factory brass to the AI chamber. The round when ignited then slams back against the boltface as pressure rises and the case grows to the new chamber size, and all the while the primer is trying to back out of the pocket due to the extra space. Now when it slams into the boltface while protruded, it is then flattened when it is forced back into it's pocket under some very high pressures. (this can be a false pressure sign). Then as a result of the case having to take the brass flow from the casehead area instead of the neck, it could quite possibly stretch enough to start the tell-tale shiny ring that tells you the casehead seperation is in your very near future.

Now,..if that old case from the original has the correct crush fit against the datum line of the new AI chamber, then I would have to say that the cases were about 86'd anyway. The splits tell me it was work hardened and the shiny rings I could go either way with depending on the headspace question.

why chase the game when the bullet can get em from here?....
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