Hi all.  Is there a "rule of thumb" for storing ammo in ammo cans as it relates to the size of  dessicant packages?  Or am I over thinking this.  Thanks

I am not sure about a rule of thumb.

I get a bunch of free "shoe box" size dessicant packs.

I load up a bunch of ziplock backs with 140 rounds each (5x28 round mags) I put a dessicant pack in each one, then throw a couple on the bottom and a couple more on top after I fill it up.

30 cal ammo can holds 4x140 round "battle packs" 50 rounds of 9mm, three loaded mags and a contractor trash bag.

Don't know, but I fit about 840 rds per can and still squeeze in a 4"x4" x 1" thick desicant percan

It's ammo.  It's not going to let air in and do anything to the powder and primers and if the seal on the can is in good shape, whatever air ins in the can when you close it will have a very small amount of moisture in it.

If the seal goes bad, no amount of dessicant will be enough to stop moisture from getting to the ammo and corroding it over time.

My thoughts.

I have stored numerous cans of ammo for decades without desiccant and I have not had any problems.
The only time I use desiccant is in cans I open frequently.

Well I like to pack mine in 4 Pocket style bandoleers: http://www.ar15.com/content/page.html?id=299

From a previous post:
So I like to store my reloads and new ammo for .223 sort of how the military does it (on stripper clips, in cardboards, inside bandoliers, & stored in a ammo can).  Now I don't know how to sew but my mom is very good at it, she has spent more $$$ on sewing machines than I have on guns.  Anyway she took the measurements from a military 4 pocket bandolier and replicated it with out the strap.  So below is a list of materials of what i use for ammo storage and some pictures.

List of materials and where I got them:
from various sources: light weight fabric different patterns
from various sources: 50 Cal ammo cans
oldsargesdropzone I bought: M16/AR15 4 Pocket Cardboards- NEW- 350 Ct. = 10500 rounds
oldsargesdropzone I bought: USGI M16/AR15 .223 Stripper Clips- NEW - 1,000 Ct.
Walmart: Tacky Glue: found in the craft section, this is to glue the pocket carboards
Walmart: cone shapped (more trapezoid shape) coffee filters
Hobby Lobby: 5 lb bag of desiccant aka (Dri Splendor Silica Gel) use the many 40% off coupons out there and the final price will be ~$7.00
I don't normally pack GI spoons I have some but I prefer the Thermold/Canadian Stripper Clip guides (IHMO are the best!!!), I try to always keep one in the range bag etc...

I pack them in there like this: http://www.ar15.com/content/page.html?id=299

So in the pictures I took show 4-5 different fabric patterns of home made bandoliers and a couple of the home made desiccant packs.

You guys go to a lot of trouble, I leave it in the case it came in.  Loose bulk ammo goes in an ammo can.

50 Cal ammo can and part of a sock filled with white rice, does the job nicely.