Can a load change its accuracy with time?

Nunu

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Oct 28, 2013
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Don’t worry about it. You know how lawyered up everything is now. I don’t recall a single instance of a munitions company being sued over this particular problem. If ammo was dangerous after less than two decades you can guarantee they’d be covering their butts and putting expiration dates on the stuff. Go shooting!
Do you think it’s only for reloaded ammo? But couple of weeks ago I found some reloaded ammo which are labeled 11/2011. They were once fired Lapua brass, 168 grs Amax with 42.0 grs of VV N140 and FL sized. Shot them all, more than 50 rds no problem and with almost the same accuracy.
 

MagnumManiac

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Feb 25, 2008
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2,980
Ok, here is the reason that this rarely occurs with factory ammo.
They blend a fast powder that gives them the ballistics they want. The reason they do this is two fold; firstly, it costs less to use less powder, secondly, they know that a crimped round with a faster powder produces a smooth curve under MAP due to a high start pressure. This has been known ever since smokeless powders has been used. This is why factory ammo can work in many different firearm types.
The only difference to this is Cordite. It is NOT a progressive powder, it had to be used as long strands to slow the burn.
Factory ammo, generally speaking, has a fair amount of air space, this type of charge doesn’t change from transporting and handling, but compressed loads, even slight ones, can change.
Hope this clears this up.

Cheers.
 

Lefty7mmstw

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I read in a book where the author said he had a load that was accurate if you shoot it within a few days. But it sets for a while, the accuracy is unreliable. I have experienced this, but decided it might be temperature and switched my load. But I have suspected this with other loads. I recently tried to pull a bullet out of a cartridge loaded a few years ago. It would not come out. I had to give up. I could probably shoot it, but the neck tension must be incredible. Any input on this phenomena is much appreciated. I have loaded enough 300 WM to last for years of hunting. I hope I did not make a mistake.
tap the pills in a few thou. with your seater to break the cold weld. It will come apart easily then. I've got thousands of rounds loaded and have hardly ever experienced this at all. It can happen though with certain circumstances.
 

Lefty7mmstw

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This was an interesting post and curious to see what others add.

A couple of years ago I went to the range with reloads and my dad’s old rifle. When he was alive, these were his hunting loads. I never shot his rifle much, but decided to take it along on the range trip just for the heck of it.

first shot, stuck bolt. I got it open and wondered what the heck. Decided I shouldn’t send any more of these downrange.

I got home and pulled one apart. There was certainly some corrosion around the base of the bullet. I pulled another one, it actually acted as if it was pressurized and popped a little. I was using a collet puller. It too showed corrosion.

I then decided to pull them all and dispose of them due to finding this. I chalked it up to being old. I did pull a bullet on reloads I found dated the same for another cartridge and everything seemed fine.

not exactly sure why they behaved differently. Same powder and load date, but different bullet, but Dad’s loads were 300 WM, and the comparison load was 30-06. Both with H4831 but the 300 WM loads had a Nosler partition and the 30-06 loads used a Hornady Interlock. Oh, and the load dates were around 2005 if I recall.
If you heard gas escaping from a round as you pulled it the powder was degrading. h4831 isn't usually a powder that this happens to but all powder can degrade if it is temp. abused a good bit. It is after all organic. To me it's an oddity you had this happen with 4831 as I was burning up a bit of ww2 surp. as recently as 20 years ago with zero issues. I did have a keg of I5010 go bad though and it caused corrosion in the casing and bullet too. 8# of fertilizer for the lawn...
 

Chadp82

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May 3, 2020
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Location
Colorado
If you heard gas escaping from a round as you pulled it the powder was degrading. h4831 isn't usually a powder that this happens to but all powder can degrade if it is temp. abused a good bit. It is after all organic. To me it's an oddity you had this happen with 4831 as I was burning up a bit of ww2 surp. as recently as 20 years ago with zero issues. I did have a keg of I5010 go bad though and it caused corrosion in the casing and bullet too. 8# of fertilizer for the lawn...
I thought this was odd as well, and have never encountered this otherwise when I have pulled bullets. As I noted, there were some other loads with the same powder loaded at the same point in time (based on the date label on the box), and I pulled one just to see if this affected them and it did not. My dad was really good about labeling things, so I have no reason to believe that dates were off, but it is possible also. The 300 WM loads were for my dad's rifle (the ones where i saw the corrosion), and the comparable 30-06 loads were for mine. After his passing I inherited some items, these being part of them. The '06 loads were in the back of the reloading cabinet and probably forgotten about by dad that the were back there, as I usually don't have loads go more than 1-2 years old that I make up. I have since shot the '06 loads with no issues (there were 25 or so), but when I pulled the 300 WM loads, about 50% showed some sign of corrosion, and the other 50% did not, but I played it safe and pulled them all. The ones w/o corrosion evidence I inspected and cleaned, any cases that showed this corrosion on the base of the bullet I scrapped.
 

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