Following up on "old powder"

[Mobuck]

Since I got several responses on my finding some decades old powder, here's question: We all know that our reloading data manuals should be kept current. How does this apply to 30 year old powder?
Everyone is scraping and scrounging to save a bit of $$ or just find components so our supplies may be several years old but we're using current data.
No wrong answer. IMHO
So opinions welcome.

 

[krw]

Powder can vary from lot # to lot #. Reloading covers a great number of people. This guy loads a 45-70 for lever action, and this guy loads a 6BR trying to get a 3", 5 shot group at a 1000 yds. 45-70 guy will never know the difference, 6BR guy will. It just all depends on what you want and expect out of your reloads

 

[Johnnu2]

I keep a couple of old reloading manuals just to make comparisons if that concern comes up; then, rely on the more conservative information as a starting point. Also, a call to the manufacturing company might produce some information (?).....
J.

 

[contender]

As mentioned,, no real wrong answers here.

I too keep old manuals. And I study data a lot when I'm working up a load. If I have older powder,, I start with data from the manuals from that era, and compare them to the newest manuals. Sometimes,,,, you'll see a difference,, (often a small difference,) and sometimes no real difference if any at all.

 

[AZ10X]

The only difference in burn rate that I am aware of was with pre 1973 IMR 4831 which was previously military surplus 4831. Actually the pre '73 surplus powder had a slower burn rate. I would venture to say that you can apply current reloading data to your 30 year old powders. As I stated in an earlier post Vihtivouri 500 dual base series powders do change with age due to the migration of the nitro to the top of the powder gains making the burn rate faster and pressures higher. Below is a photo of a pre IMR surplus powder can.

 

[MZ5]

I have some older load manuals. I like the technical articles and information, but don't use the load data unless I happen to have powder that old. Historically speaking, I shoot far too much to ever have old powder. However, I 'retired' from competitive shooting a few years ago, and so now some may get 'old' (but not in the sense you guys seem to be talking about) before the last of it gets used. We'll see.

Norma's reloading manual No.2 has some excellent technical info about what happens as powder ages. Speaking overly broadly, peak pressure generally increases even though bullet speed generally decreases. That kind of technical article is why I like and keep some older manuals.