What happens to ammo as it ages?

[Nando Aqui]

35 years ago I bought 500 hundred rounds of 30-06 MP ammo, from a local guns shop, in 5-round clips, for 3¢/round. Head stamp SL 52. (I still have about 200 rounds left.)

A year ago, I bought 480 rounds of Danish 30-06 in en-bloc clips and bandoleers, for 29¢/rd, shipped, from J&G Sales. Head stamp: AMA 91

Last June, I bought 624 rounds of Danish 30-06 in en-bloc clips and bandoleers, for 31¢/rd, shipped, from AmmoMan. Head stamp: AMA 80

About three months ago, I took my M1 Garand and FN49 and shot about 16 to 20 rounds of each of the above ammo. They all worked fine. I thought perhaps the older ammo, the SL 52, might have lost some 'speed', but it seemed to be about the same as the others as far as elevation. True, I didn't do a super accurate, bench rest evaluation, but I was able to get 2-1/2" to 3-1/2" groups at 100 yards with any of the rifles-ammo combinations from a padded rest without straining too much

Yesterday, I received 840 rounds of Danish 30-06, in 30-round cardboard factory boxes, for 27¢/rd, shipped, from SurplusAmmo. Head stamp: AMA 72

I haven't tried this AMA 72 yet, but I suspsect it will be fine as well.

Question 1- Theorectically, how is aging supposed to affect ammunition, albeit if properly kept in a dry environment and not subject to extremes in temperatures; i.e., kept indoors? (Or, how long does the powder and the primers last if practically kept 'hermetically sealed'?) **

Question 2- Any difference between military and commercial ammunition as far as longevity matters, if the military is non-corrosive?

Question 3- Does anyone know what the SL head stamp of my 1952-vintage Metal Piercing ammo stands for, or is it too old or vague to tell?

** I have no idea how any of this Danish ammo has been stored. By contrast, the Portuguese surplus .308 that I have bought over the past two years has come in sealed plastic or ruberized bags.

Thanks -

Alex

 

[fight4yourrights]

SO much depends on the storage conditions.

Heat & Humidity are very tough on ammo.

25 year old South African surplus 5.56mm has lost a few hundred FPS

My 1903 8mm Turkish ammo doesn't always go BANG when I pull the trigger.



Quality ammo will last a very, very long time with good storage conditions.

 

[Mike Irwin]

Under ideal storage conditions, ammo can last forever.

1. In the middle 1980s I fired an original Civil War era .56-56 Spencer with ammo made in the 1870s. About 70% of the ammo went bang first try.

2. Essentially, no.

3. St. Louis Ordnance Plant, set up in, IIRC, 1943, and made ammo until the early 1960s.

 

[Jhaislet]

For me, ammo never has a chance to age

With regards to aging, powder & primers are really hard to "kill".
A buddy of mine soaked primers in oil for a couple days to make them inert.
Yet after drying out for a couple weeks, almost every one of them went bang when it met mr. hammer