25-06 over pressure

woodchopper

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well had a strange thing happen yesterday on the range

was sighting in my 25-06 using ammo that I loaded up years ago and 2 out of the 18 rounds were way over pressure, very stiff bolt lift, needed a chunk of wood to beat on the bolt handle to eject the round, had some brass flow into the ejector (Tikka 695) blew out the primers, primer pocket is oversized. The rest of the ammo was fine, I don't understand how this could happen. I know that I weigh every charge when loading, and the load is under the published book data.

So asking for opinions, could this be a case where the ammo has been rattled around for 10 or so hunting seasons in the plastic box on the quad and in my jacket pocket hot and cold enough to cause these 2 rounds to have the powder break down effecting the burn rate enough to cause the over pressure. When you look at the rounds in the box you can see that they have marks on the brass from where they have been in contact rubbing the plastic box edges.

I normally use a plastic box of 20 for hunting and it rides with me in my jacket pocket as I use rounds I replenish the box from my reloading stock (box of 50) and I am not really concentrating on using oldest first so it is possible that some of the rounds in the box of 20 are significantly older then others.

comments / opinions
 
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No, powder does not break down from tumbling around.
Could simply be a couple over pressure rounds, possibly cold weld of the bullet to the neck, but usually the neck splits or separates completely when that happens.
 
It could be that the bullet bonded to the case over the years . try seating the the bullet a touch deeper to break that bond.
Neil
 
I've had a mass of tumbler walnut shell media stay in the case, get missed during charging and only appear when the fired cartridge had pressure through the stratosphere. Yeah, I know I should have seen it when charging the block of cases, but ammo gets loaded on turrets and progressives too. Those of you who are without sin can throw the first rock. ;)

By the way, never, ever, ever add a bit more polishing compound to the tumbler when its running with cases already in it. Don't even think about it.
 
so looks like some of the brass was not trimmed, out of 65 cases I ended up pulling 30 dumping the powder and trimming them all to 2.490". 2 of the cases were just over 2.5" so it looks like I just loaded up some brass without checking them for length.

while I was at it I pulled about 40 rounds of 30 Carbine that I loaded with 90grn Hornady XTP, the hollow points were just not feeding
 
Every rifle is different, but in the couple dozen rifles I have measured using the Sinclair chamber length gauge, almost all of them are about .030" longer than "max case length" in manuals
 
so looks like some of the brass was not trimmed, out of 65 cases I ended up pulling 30 dumping the powder and trimming them all to 2.490". 2 of the cases were just over 2.5" so it looks like I just loaded up some brass without checking them for length.

while I was at it I pulled about 40 rounds of 30 Carbine that I loaded with 90grn Hornady XTP, the hollow points were just not feeding

good to hear you found that out. this is where i was going to go awell.
i worry about this alot, as i hate triming lol but have to do it to be at ease in the mind about that fact
 
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