Q: how much can heat/humidty effect modern ammo?

Curious, how much-if at all- can heat/humidity effect loaded (magazine) ammo?
Took the .45 out back today to touch of a few rounds. Ammo was Blazer Brass 230 grain TMJ.
Id' bought the box a few months ago, shot off a few rounds, and it was fine. Had'nt much chance to fire any more until today.

Now, my .45 has such low recoil -regardless of ammo- (standard pressure, not +P) to begin with, but today's shooting "felt" like even less oomph.
(Hard to describe) Cycled the action just fine, no jams/FTF's at all- but the already mild recoil felt even lighter, smoother than normal.

Case in point- I'd let the wife touch off 2 rounds-she's very gun-shy, and had not yet fired this pistol, or ANY .45 auto before this. I didnt expect her to have much issue with the recoil, but.... Said it felt "perfect" for her.

Also, the rounds were impacting about 1.5-2" below point of aim @ 25 feet , consistently.
Normally this pistol is dead-on accurate with all loads I've put through it so far.

Also, recovered one of the rounds (the other 6 I was unable to locate due to failing light/evening-will look for the others in daylight, tomorrow)-it had passed through 1 jug water, 1 900-page phone book, and 1 old Dell ATX tower-impacted the trunk of the massive Oak tree that I used to back-stop it, then fallen to the ground at the base of the tree. The recovered round displayed very. very little deformation (even for a TMJ . Impact on target was nowhere near as "dramatic" as usual- I actually had to go over and double-check to see if I had even hit the jug, at all. (was expecting-for demonstration purposes for the wife- the usual exploding jug and water spraying all over the place effect,but no dice). Small entrance hole 2" below center, small trickle of water leaking out- massive hole out the back of the jug.

Is it possible the ammo/powder could just be deteriorating or whatever, due to the recent heat/humidity we've been having? Or just nearing the end of it's shelf-life? No idea how long that box of ammo may have sat on the store shelf prior to my purchase of it, so...

It takes a lot of heat, usually in cycles of hot-cold-hot-cold, amd lots of humidity in similar cycles, to have a significant effect. Folks are buying surplus ammo all the time and seem to have no problems with it. Some issues you might see are oxidizing of unjacketed lead - if nothing else it's horribly abrasive. And if you believer that military ammo storage warehouses are climate-controlled I'd like to talk with you about my oceanside property in Arizona - I'll let it go at a good price.

The old canard about the box of ammo in your trunk for a few years being no good was probably started by a gun store clerk who got a commission for every box of ammo he sold.

Now, if you were storing your ammo in water or in oil you might see deterioration fairly quickly.

stay safe.

Good question.

Well I'm not being a funny guy here - but maybe this will help you look at it from another perspective: I goofed up and washed & dried a couple of +p rounds of ammo that I had forgotten in my range jacket. (I know...Dooh! Homer move!) Since I was going to the range the next morning I took them along out of morbid curiosity. At the end of the session I cautiously loaded them into a magazine, racked the slide and said a hail Mary. Guess what? No issues and very similar to all the other rounds fired in performance.

The point is modern ammo is hard to beat for its reliability. Even after being through: wash, rinse, spin & bounced around in dryer at high heat.

heat, humidity, old

When I was 18 my father bought a 30-30 winchester and 2 boxes of ammo. Last year I found one of those boxes stored away in my garage. I have moved several times from central Oregon to Salem. Turner, Falls City... weather in Oregon has extremes from over 100 degrees down to below zero. This ammo was in a flood and outside these many years (I'm past 50). I took this ammo and cleaned it off (some patina) and it fired off just like it did 30+ years ago. I don't have any trouble stocking up, or worrying about old or slightly weathered ammo.

willigun said:

When I was 18 my father bought a 30-30 winchester and 2 boxes of ammo. Last year I found one of those boxes stored away in my garage. I have moved several times from central Oregon to Salem. Turner, Falls City... weather in Oregon has extremes from over 100 degrees down to below zero. This ammo was in a flood and outside these many years (I'm past 50). I took this ammo and cleaned it off (some patina) and it fired off just like it did 30+ years ago. I don't have any trouble stocking up, or worrying about old or slightly weathered ammo.

Click to expand...

Hmm.. didnt think so, either.. just couldnt figure another explanation for it seeming less "oomph" than normal..It's on my hip constantly- no out of the ordinary exposure.. does go from heat -outdoors- to cold- ac indoors often, but not enough I'd imagine to effect anything..
Was finishing off this batch, anyway, to re-stock/rotate ammo as per routine. So no biggy, really.

Maybe its due to your water softener being on the fritz and the water in your jug was just too hard. Ok bad joke I know. If you do ever solve the mystery let us know. For some reason this has my curiosity peaked.

Felt recoil is subjective. At the end of a range session it is even more subjective.

Unless you notice it bouncing off the paoer I'd say don't worry about perceived difference. Next time you are curious get a chronograph and see if there are major differences. (I know, hard to do with a round you just fired.)

stay safe.

I depends on the powder. Most powder produces higher pressure and velocity in hot weather, lower in cold weather. Some powder works opposite that. If it's factory ammunition it's not cannister (off the shelf powder) so you don't know which way it works. At best, there's some tribal knowledge from people who have chronographed that factory ammunition at the ends of the temperature extremes.

I have shot WW2 surplus ammo with some signs of corrosion. Not one miss fire. Maybe the blazer ammo is light loaded.