old ammo vs new ammo

[jhalcott]

What could cause a difference in performance in ammo loaded a year or three ago, and stuff loaded this year?. I mean a difference in velocity and/or accuracy!
A friend and I had this discussion and he feels it's because the powder is deteriorating. I think the powder is breaking up from rough handling ,IF there is any change at all. I'm talking about using the SAME 8 pound can of powder ,primers and other components. When I used 4831 in my 6mm and shot ground hogs every week end ,I'd load all my ammo in the early spring. The ammo in the boxes would bounce around in my jeep for several months.In the fall I'd get some pressure signs and an occasional miss that I couldn't explain. When I pulled the bullet from a case once ,I noticed the powder was not all the same as when I loaded it. There was some short bits mixed in with those LOGS. The charge weight was correct!

[Freightman]

The handling is not the problem, leaving it in a Jeep all year is, wide and wild temp. changes and varring humidity changes. I have literley shoot thousands of rounds of ammo that is older than myself and it gave consistant results. The storage of ammo is the difference. I do not know about where you live but in as little as 30 min. sitting in the sun it can go from an AC 70 to 150-175 inside of a car ect.

[MT Gianni]

Were the charges filling the cartridge or was there room to rattle. With the powder up to the neck and the bullet seated to the powder or compressed I think rough handling issues would be minimized if not eliminated. No actual experience just my thoughts. Gianni.

[Ricochet]

High temperature is the biggest thing that deteriorates powder. The U.S. military used to (and likely still does) keep samples from every batch of propellant under observation in storage at 150°F. When it evolves red fumes (nitrogen dioxide), the powder's gone bad. That would happen in a matter of weeks to a few months at that temperature, and the time it lasted at that elevated temperature
was thought to be proportional to its lifetime in normal service conditions. Ammo would be accordingly pulled from service and sold as surplus or scrapped when its anticipated lifetime had expired. A lot of our surplus powder and components have come on the market in just that manner.

It's quite common for the temperature in a parked car in sunshine to go well above 150°F.

Store it in a cool place and it'll outlast you.

I think the point raised about vigorous shaking of loads with loose powder breaking grains is well taken.

[jhalcott]

The ammo was not left in the Jeep ,unless I spent the night in the field. When I got home the ammo was put in my ammo locker till I needed it again. I can not explain the occasional flier or the pressure signs in the ammo .The temperature was cooler in late fall then in the summer months. I did load up some 22-250 ammo in January that gave me serious pressure signs in july/August when the temps went into the hi 90's and low 100's.

[Ricochet]

Was it the original surplus 4831, by any chance? Hodgdon sold that stuff up till about the end of the '70s, I think, and I'll bet there were local stocks for a long time after that. It was originally WWII surplus powder for 20mm. When DuPont reintroduced 4831 circa 1980, everyone quickly discovered that loading data worked up for the old stuff wouldn't work, even though the new stuff was supposedly made to the original specs.

[KYCaster]

Years ago when I first started shooting IPSC I was lubing everything with 50/50 Alox. I got tired of wiping off the excess lube and bought a vibratory tumbler. Couple hours in corncob and the sticky mess was gone...trouble was....it changed the burn rate of the powder. I tried it with several different handgun powders and in every case the velocities increased...some by a very small margin and some substantially. I decided that practice was a bad idea and changed lubes so I didn't have to deal with the Alox.

So, yes vibration will change the burn rate of powder.

Jerry

[Lloyd Smale]

ive loaded 223s and 308s in mass quainitys for the black guns on a dillion for years and allways tumbled after they were loaded for about an hour to remove lube and have never seen it effect anything. Ive seen excessive heat raise pressure in ammo that was sitting in a hot truck but if the ammo is coo.ed it seems to go back to normal. Ive never seen ammo that sat for years increase in pressure. I would think that if anything it would decrease. What i have seen in heat and long term storage is lube contamination. Any lube on a base (even tumble lube) will contamintate powder especially if the ammo gets hot. tumble lube is fine it your going to shoot your ammo in a short time or can keep in at cool temps but id never again load bunches of it for long term usage.

[No_1]

Is it possible your pressure signs are tempature related. You have indicated you load at the begining of the season and shoot all season. Did you work up loads at the beginning of the season when temps are cooler and then noticed signs at the end of the season when tepms were warmer? Also note that 4831 can be cut in the metering process. It may be a case of all your loads contained "cut" pieces but you never noticed until you pull some down.

I have ALWAYS tumbled my pistol loads after they were loaded but never my rifles loads. Each rifle load gets the visual inspection once done. I use 2 rags (one in each hand) and wipe as I inspect before I put it in the case.

R.

[jim4065]

Has anyone compared loads after storing some bullet down and the rest bullet up - everything else being held equal? I would think that bullet down would have far less capacity for lube contamination in a warm environment. Just a thought.:coffeecom

[Bret4207]

ive loaded 223s and 308s in mass quainitys for the black guns on a dillion for years and allways tumbled after they were loaded for about an hour to remove lube and have never seen it effect anything. Ive seen excessive heat raise pressure in ammo that was sitting in a hot truck but if the ammo is coo.ed it seems to go back to normal. Ive never seen ammo that sat for years increase in pressure. I would think that if anything it would decrease. What i have seen in heat and long term storage is lube contamination. Any lube on a base (even tumble lube) will contamintate powder especially if the ammo gets hot. tumble lube is fine it your going to shoot your ammo in a short time or can keep in at cool temps but id never again load bunches of it for long term usage.

Lloyd- Are you using ball powders? I seem to recall reading ball powder are physically much tougher than stick powder as far as vibration and crushing go. Just a thought.

[DeanoBeanCounter]

I don't know what causes it but age does make a difference.
My brother has a competition grade 308 that he uses for competition. He tells me that when he shoots ammo that is 6 months old that he gets primers backing out but it never happens with fresh ammo. I don't know what powder he uses.
My own experience is I have an old 30-30 that had to much head space. I had 100 rounds loaded with I think 150 grain bullets. I used Winchester 748. I took the rifle to a guy to fix, I knew it would take some time to get back. In the mean time he was called to Iraq for a year. So, it took over two years to get the gun back. My Marlin model 93 worked like a charm. The ammo I loaded just sat in the closet on it's side all that time. It just got moved from time to time to get at other things but never bounced around. When I finely go to shoot it I loaded up the gun, fired the first shot and almost got knocked to the ground. Checked the primer and it was backed out. I know I should have stopped there but I thought it just might be a fluke and shot two more rounds with the same result. I stopped there. Took the ammo home, opened up 97 rounds. I checked everything out, the charge was right, the bullets were right, no problems. I reloaded a few rounds with the same powder and charge and bullets and brass. Went to the range and they shot just fine. I shot up the rest of the powder without flaw.
My best GUESS is that there must have been a gas buildup inside the ammo. These were Speer jacked bullets.
Any other guesses?
Deano

[Lloyd Smale]

brett mostly ball but do it with stick powders too and havent noticed a problem.
Lloyd- Are you using ball powders? I seem to recall reading ball powder are physically much tougher than stick powder as far as vibration and crushing go. Just a thought.

[Ricochet]

Ive never seen ammo that sat for years increase in pressure. I would think that if anything it would decrease.
That is what one would intuitively think. I have an article I downloaded from a ballistics seminar site (before they restricted access) that explains why it's not so. As nitrocellulose ages, there is some denitrification, which decreases energy. But it's a relatively small effect, just 1-3% or so over the long life of the powder. However, as the long chain nitrocellulose molecules age, the polymer chains break in various places to make shorter length chains, the overall composition not changing much in this process. The shorter chains of nitrocellulose make the structure of the powder grains more brittle. On firing, powder grains can shatter from the primer blast, exposing more surface area to the burning gases and speeding up the burning rate. (Of course as we've just been discussing, other mechanical vibrations or shocks can fracture powder grains before firing.) The increased burning rate of broken powder overrides the small loss of energy from denitrification. Anyway, the article explained that the usual observed effect of aging on pressure is a rise in pressure, that stored stocks of military ammo are periodically test fired, and when it exceeds the allowable maximum average pressure it's surplused or scrapped. I've figured since reading this article that this explains why some of the old Turkish 8mm Mauser ammo is so very "hot."

[TAWILDCATT]

how do you explain ammo that is 30 ys old working fine.primers should not pop out if headspace is right.military ammo gets more tossed around than civilian.what about the surplus that was made in 40s.
I have lebel ammo powder is fine primers are non corrosive and are mostly duds.
7.7 jap machingun ammo the same only those are corrosive 1944. I pull bullets transfer the powder and bullets to new cases and shoot.
The factory tumbles new ammo to clean. something else is involved.
and age cant be the cause.at least not a few months.I had 1887 dated blackpowder 43 mauser ammo I got in Trinadad[thats in tropics] I fire in 1956 and it worked fine. you figure. :coffee: :Fire: :coffee:

[Ricochet]

I've shot plenty of 1941 and 1942 ammo that worked fine, too. Age isn't the only factor in aging. Storage conditions, especially temperature, are critical. Powder can deteriorate more in a couple of months at 150°F than in years of proper storage. And powders are not all the same.

[TAWILDCATT]

Have you ever used surplus ammo.alot is 50yrs old and works fine.I have 7.7 jap machinegun ammo that is 1944 and 8 mm lebel from the 1970s.both are duds but its the primer. I pull and pore powder and bullet in new shells.powder works fine.factory tumble clean, loaded ammo.
that 30/30 should not pop primers unless it has headspace problem.
I had 43 mauser ammo I got in Trinadad.fired it in1956 and it shot fine.the headstamp was 1887.
age does affect primers and powder lasts.some war time powder goes bad because they dont remove all the acid.russia was bad for this as the ammo went from factory to front.:coffee: :Fire: :coffee:

[Ricochet]

Have you ever used surplus ammo.alot is 50yrs old and works fine.
Yep. Most of it works fine. Some of the old Turkish stuff is so hot it'll rock you back on your heels, and often pierces primers. That's a demonstration of rising pressure with age, I suspect. Can't prove it because I don't have a time machine to test it as it was loaded 65 years ago.

[leftiye]

Primers "popping" out denotes that there is room to do so. There shouldn't be any room for this to happen.

You should be able to expand case heads with NO backing out- to the point of locking up the action! The obvious causes allowing backing primers out are either excess headspace and/or springing the action (exception-low pressure squib loads and undersized cases). If you're springing the action, you might want to stop before you eat your bolt.

[Ricochet]

Piercing around the firing pin, not backing out. Yes, there are other causes of this like incorrect firing pin protrusion and space around the pin. It's only happened with my lot of 1942 Turk, which gives 3000+ FPS muzzle velocities with sticky extraction and flat primers (which occasionally pierce.) And they do leak around the primer cups a bit.

Hot stuff.

[jhalcott]

there is DEFINETLY more to this than I thought. I hope I don't start a fight within the family here bringing it up! I too have shot ancient ammo with seemingly no problems. I did not have a base line to compare with though. If it went bang and the bullet hit the target ,I was happy. I did have a batch of 45-70 ammo that was "hot". When the bullets were pulled the the black powder had formed into a solid lump. I have no idea what the velocity was, but recoil seemed higher than normal. Or the the shell did not go off.

[leftiye]

Rick O'Shay, I was more reacting to Deano's #12 post.