Has anyone choreographed IMIs brown box m855 in the cold? I was curious about the temperature stability of the powder they use, I pulled a round apart and noticed it was a ball powder, so it made me wonder about the temperature stability

I know IMIs m855 is on the hotter side at normal temperatures, but when it gets cold, does it lose a lot of velocity?

We should get a thread together about the varying temperature stabilities of commercial loads. In my AO we range from 100F to -20F summer to winter, so my hunting loads generally use temp stable powders, now im curious about how factory ammo compares

Not any more, it isn't.  IMI has down-loaded their M855 sold in the US by nearly 100 FPS.

A legacy lot of IMI M855 fired from a 20" Colt barrel had a muzzle velocity of 3112 FPS.  A lot from 2021 had a muzzle velocity of 3015 FPS.

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I figured, all manuf's seem to be downloading Current loadings

I don't particularly like m855 for anything, but I got 2k rounds of IMI 855 in 2016 for too good of a deal to pass up.

You should be good on velocity then.  I don't remember the exact time frame that IMI started downloading.  I want to say it was around 2017-2018, but I could be wrong.

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Nothing wrong with M855 nor M193 for SHTF or plinking… it’s good ammo.  Not precision by any means. But I defiantly keep a few thousand rounds hidden away.

As to you’re question, I don’t have that particular lot of ammo you speak of.  But any ball powder 5.56  I’ve seen swings of over 100FPS in the temps you mention. -20 is pretty chilly. And I have let my ammo sit outside just to test it in those temps …..Anchorage and Fairbanks Alaska

Funny thing is at 300 yds it’s still minute of man… and that’s my personal gauge for that type of ammo. Even @ -30 I’ve never missed a man sized target at 300 yards… they might not all be clean kills however it’s on paper.

For whatever it’s worth, that my experience.

On another note…

In the warmer weather even the ball powder stays fairly consistent… it might get a little hotter per say. But the POA vs POI is fairly predictable.

I’ve noticed in the harsh cold even with hodgdon extreme powders. The POA vs POI shifts .. you might get good groups however those groups walk. Not more then a MOA or so with the extreme line… but they do walk

And with ball powder they seem to spread out ( Open up ) noticeably, as well as walk.

Use varget and and 77s in the cold…. It’s the best I have found. And just zero  youre sights in the conditions you are in.

I can routinely hit 3,115+ in my 22" with can in 70F from M855, and on occasion almost 3,500 with Independence and IMI M193. Those same Lots in 30F~, will give me about 2,875-3,050 fps for M855, and 3,250 to 3,3XX. Not sure how much that helps you