IMR 4350 shelf life

[cwheel]

Had an interesting experience yesterday. I took my 300 win mag out and shot some rounds across a chrony that had been loaded back in 1989. I was noticing that, over the years, this lot of ammo was starting to show more drop at longer ranges than it did when loaded. Back when loaded, this ammo went through the chrony @ 3175 FPS with a deviation of 14 FPS when loaded with 72 gr. of 4350. Yesterday, the same lot loaded in 1989 went through the chrony @
shot #1 = 2854
shot #2 = 3105
shot #3 = 2890
shot #4 = 2969
Not only was there a 10% drop in speed, but the deviation was all over the place. Ammo was stored in a nice dry place at temps between 60-85 degrees. I guess the only thing I've proved is that everything has a shelf life. Guess I'm going to have to pull this stuff down and work up the loads again with fresh IMR 4350 ??
Chris

[too many things]

must be why the WW II ammo is still around
would guess your loads were not good at time
I have loads from the 60s that are still good

[Lead Fred]

Storing powder vs storing load ammo.
Powder not in metal should work for many years.
The gobermint rotates loaded ammo after 30 years.
Ive got a little less than 100 lbs here. 99% is in the cans/bottles it came in.
A lot of it is over 10 years old. Any time I use some, it works like new.

[Artful]

Had an interesting experience yesterday. I took my 300 win mag out and shot some rounds across a chrony that had been loaded back in 1989. I was noticing that, over the years, this lot of ammo was starting to show more drop at longer ranges than it did when loaded. Back when loaded, this ammo went through the chrony @ 3175 FPS with a deviation of 14 FPS when loaded with 72 gr. of 4350. Yesterday, the same lot loaded in 1989 went through the chrony @
shot #1 = 2854
shot #2 = 3105
shot #3 = 2890
shot #4 = 2969
Not only was there a 10% drop in speed, but the deviation was all over the place. Ammo was stored in a nice dry place at temps between 60-85 degrees. I guess the only thing I've proved is that everything has a shelf life. Guess I'm going to have to pull this stuff down and work up the loads again with fresh IMR 4350 ??
Chris

One other thing to consider is neck tension - the cases have been trying to grip those bullets for 27 years, they may be getting tired which will effect both velocity and consistency.

[shooting on a shoestring]

Along the lines of Artful's thinking, the brass is also more brittle than 27 years ago.
It could very well be not just the powder or the brass hardness and neck tension but the combination of it all.

And another small piece of the might be the striker in your rifle. Could it be the lube in the striker tunnel is older? Has the striker spring lost any power? Might be the primers are not getting hit with the same force they were 27 years ago.

I'm shooting in the dark here. Really don't know. Just raising some possibilities.

[Beau Cassidy]

A few things to consider..

Cold weld between the bullet and case.

Deterioration of powder. I have about stopped using IMR powder for that very reason. I have a lot of 1 lb cans of 3031, 4064, 4350, and 7828. They are probably 25 years old. Some of that powder is the nice rusty color with a lot of dust indicative of breakdown. I do not consider that acceptable when I am also sitting on hodgdon rifle and pistol powders from the 60's that looks as good as new.

[clearwater]

The only stick powder I have had gone bad started with Dupont, not IMR. Still using some excellent flake Dupont #6 pistol powder tho.

[lylejb]

I just fired some 30-06 I loaded with imr 4350 in 1993. 3 of 6 in the X ring at 100 yds. No chrono, but also no adjustments to the scope. I'll claim responsibility for the 3 that didn't hit the X. I'm fully confident these are as good as the day I loaded them.

[cwheel]

I've only used this 300 win mag for hunting, and because of that, my round fired count through this Remington 700KS is low. Just bought a new 8lb. of IMR 4350 and will look closely at the powder removed from the still loaded cases when I pull them down and compare between the new jug when I open it. These are all once fired Winchester cases that had careful case preparation when loaded back then. So, at this point I guess all I can do is speculate on what is happening. Regardless, I'm going to buy new, fresh cases and start from scratch. The 3175 fps with a 165 gr. Sierra gameking is what puts the drop compensator in my Shepherd P-1 scope to the drop compensator calibration in the scope. Not hunting this year, was not able to draw tags here, so have plenty of time until next season to get it right. Thanks to all for the advise, didn't consider the cases could end up being a issue, I'll look closely at them when I pull them down.
Chris

[birddog 6]

I had a plastic 1lb jug of IMR4350 that the lid just rusted and crumbled and also had a bad smell and funny color to it. The can was about 8 years old and was stored with several other types of IMR that were all fine. I checked some loaded rounds that I loaded with it and a lot of them were corroded around the neck and bullet and also inside the case. I had to throw away a lot of brass. So I guess it sometimes does go bad.

[John Boy]

shot #1 = 2854
shot #2 = 3105
shot #3 = 2890
shot #4 = 2969
Indication that the case crimp is not uniform

[Artful]

shot #1 = 2854
shot #2 = 3105
shot #3 = 2890
shot #4 = 2969
Indication that the case crimp is not uniform

Not the crimp so much as neck tension on the bullet

[leadman]

I can only assume that the Remington is the same rifle used for the initial shooting. Another thing that can cause velocities to vary is how the rifle is held for each shot. I have to use a Leadsled because of my neck so the velocity is usually slightly higher when the gun is fired off a front rest only or just my shoulder. Even the amount of weight I add to the LS will cause a change in velocity. Primers can also cause what you are seeing.
I recently started using Alliant RL17 as a replacement for IMR4350. I found it is accurate, has a milder blast, and the guns seem to recoil less.

[farmerjim]

I am using IMR4350 that I bought in the mid 1960's from Herters for less than $2 a pound. No chrony, but 3 shot group was less than 1 in at 150 yards.

[cwheel]

Same rifle, same rifle rest, same everything during the chrony testing as used to work up the loads in the beginning 27 years ago. All of the once fired brass was sized, trimmed within .001. Same lite crimp was used on all. Only difference is time. Even with these old eyes, this setup still shoots less than a 1" group @ 100 yards. ( I'm surprised by that ) Farmerjim, that is what fooled me in the beginning. My 100 yard zero never changed. What did change was shooting these rounds @250+ yards. I have one of those Shepherd P-1 scopes on this rifle,that have the built in range finders on this rifle. Have to say that Shepherd scope is some of the best scope money I've ever spent, I don't have to guess at ranges anymore and have to think about hold overs. You fit the range finder to the deer body and make the shot, doesn't take 5 seconds to do. 100-150 is still going to print well at these ranges. Further out, the further off the drop rate is and over the last 3 years or so, the longer ranges weren't matching the range compensation in the scope. I guess if I was hunting at a closer range, it would never matter. Out west here we tend to get some longer shots. I won't shoot much past 400 to keep it a ethical shot, something I can make. You don't usually get shots under 100 yards here, more often it's around 300+. Going to order new cases today, when they get here, I'll pull down the old rounds, see what I have going on. Odds are, it's the powder.
Chris

[NSB]

Two years ago I bought a new 243 and shot some shells I loaded in 1988 out of it. I got five shot groups of .4" and .6". Wonder how much better it would have shot before it got tired on hanging onto those bullets all those years.......? I don't think neck tension grows or decreased over twenty years. It's pretty stable. So's the powder if kept cool and dry. Those shells may have had the same performance years ago when you loaded them.

[AKbushman49]

cwheel- I would have to go with Beau, ie. cold weld. I had some 35 Whelen I loaded before it was a factory cartridge, did the same thing, velocity variations all over the place, as well as reduced accuracy. When I went to pull the bullets I had a noticeable variation in effort to pull them. (I use a collet puller in a press). Could see a little corrosion/oxide on the boolit as well as inside neck of case. This ammo had been in storage for years in a std mil spec ammo can. The exterior of the round was pristine, no indication of corrosion. (might have been the bullet lube too, t'was the old lyman stuff). bushman

[ole 5 hole group]

I had 12#'s of IMR-4350 go bad that was properly stored for 20 years in their original brown can with red cap. I had 8#'s stored in pharmaceutical plastic jugs that was purchased at the same time, same lot number and it was good.

I've never kept reloaded ammunition much over two years and that would be ammunition for firearms nobody cares to shoot much, due to recoil.

[cwheel]

Just a follow up once I pulled the rounds down. Every thing looked normal in all aspects except for one thing. When pouring the powder from the cases, some of the powder was clumped up, had to tap the case to break it up to pour out. I think the answer is somehow the powder was moist ?? Living here in Nevada where it's dry with very low humidity you would think this would be the last thing to happen. Ammo stored in GI ammo cans in relatively stable temps. Neck tension seamed uniform. Live and learn I guess.
Chris

[Texas by God]

Even with velocity variations like that it can still shoot extremely well.