powder weakness

Has anyone ever found that older lots of powder over time tend to weaken when compared with the same brand but of newer production?
Here is what is happening, I have a gun that was tested with a friends loads that it functioned 100%, I took his info and loaded my own taking much care to use exactly same bullets, case and powder and primer brands, seated to his specs and crimped the same. My loads wont cycle the gun fully causing failure to lock back and a few stove pipes. The only difference in our loads is My bullseye powder was made in 1999, and its the last 2lbs of a 8 lb bottle, while his is of 2013, the Winchester primers im using were made in 2013 not sure when his were but im sure they are close. Any thoughts?

Dave,
Others a lot more knowledgeable than I will chime in here, but yes, different lots of powder will have slightly different burning rates.  They will always be very close, otherwise they can't be named the same powder type, but they will differ slightly.

You may be using a slightly different burning rate of the same powder than your buddy, so may have to bump it up a tenth or two, especially if you're using a very light charge.
Al

Thanks , loads are in the 4.2-4.6 range with a 200 and 160 lswc, more interested in the question of degradation of the powder over time, im sure slight variances lot to do exist. Also none of the common signs of powder going bad are present in my powder, still looks and smells fine.

I always had a hunch that humidity in the air will cause that. That is why I load on days with low humidity, just to make sure the air sealed in the cartridge is dry.

It may have be that you scale reads a lighter charge weight.  Check the two scales with the same weight.

I have a ohaus scientific, it is dead on and tested against test weights, I also broke down some of my friends rounds and checked the weight, so its defiantly not a scale issue.

Nahh!  I have compared some of my 40 plus year old BE with some recently purchased.  No difference.

Jerry

No, powder doesn't weaken. Powders do shift from lot-to-lot.
Was everything the same: same gun, cases, primers, bullets, COL? Any difference is weight readings between the balances? Any "dust" or acrid odor from your lot of powder?
My Bullseye, Herco, and Unique from the '70s still performs just the same, but I haven't compared to new lots of powder--so all I can say is that the powders have not weakened over time.

Has anyone taken some powder say 100 gr and let it sit out in a humid area for a week or so and then weigh it again. If it gains weight this would be reason that your loads are less potent.

pistol champ wrote: Has anyone taken some powder say 100 gr and let it sit out in a humid area for a week or so and then weigh it again. If it gains weight this would be reason that your loads are less potent.

From memory, there was a post some time ago on the old list where a member did such a test and said that the powder does gain weight.  IIRC, he further said that the volume did not change.  So, IOW, the same volume (same setting on a powder bar) became heavier as moisture was taken in.

Ed Hall wrote:

pistol champ wrote: Has anyone taken some powder say 100 gr and let it sit out in a humid area for a week or so and then weigh it again. If it gains weight this would be reason that your loads are less potent.

From memory, there was a post some time ago on the old list where a member did such a test and said that the powder does gain weight.  IIRC, he further said that the volume did not change.  So, IOW, the same volume (same setting on a powder bar) became heavier as moisture was taken in.

I have wondered why we pistol shooters measure powder charges nominally by weight, yet in practice we nearly always meter them out by volume.

Probably because machining bushings for volume is generally much less precise than weighing to 1/7000 of a lb.

Gosh, I'd like to increase my volume metered by .000035 ci, wonder where my bushing chart is, or, how far do I screw this damn thing in?

well I replaced all the older bullseye powder with some made in 2013 and loaded the rounds same as before and the gun functioned. So as to weakness it did occur, the reason is not clear, I got that old lot of powder which was about 5 pounds of a 8 left from a friend, so maybe it was exposed to moisture but it was kept in a climate controlled area at his and with me. Talking to Dave Salyer he thinks it might be evaporation of some of the nitro glycerin in bullseye.

I'm somewhat anal about my powder use, in that I open my source container long enough to dump some into my hopper and that container is closed and not opened again until the next time I'm making match ammo.  The remnants of the hopper go into a second container, considered practice powder as soon as I'm done reloading.

There is another thing to consider, but I really don't see this pertaining to the OP.  When you first dump powder into the hopper, it is somewhat fluffed up.  As the loader vibrates, the powder settles a bit making it denser.  If you adjust via your scale while you have settled powder in the hopper, and then reload the empty (or, near empty) hopper with some fresh powder, your first drops can be lighter, until the new powder settles.  Some powders are more susceptible to this phenomenon than others.  This is not the same as the baffle(less)-related issue of the contents of the hopper varying the drop due to compression forces.

Ed.

That is why ball powder is so much more consistent than a flakey type powder. It flows more
regularly and predictably.

Jerry

and, you really need to shoot YOUR loads in HIS gun to see if it won't function.

The evaporation partial pressure of NG at room temperature is very low to be almost nonexistent.  However, it rapidly increases with temperature.  IF NG evaporation is the culprit your powder got very hot (212F) at some point in its life.  You might be able to tell if you weighed your buddy's powder on a lab scale as the density will be different.  You might get better results weighing a Lee dipper for a 308 full.

I load in FL and find that often I can't leave powder stand in the reservoir for as much as 20-to 30 mins w/o it bridging. !1st 6-10 will be OK then fades lighter to 0. I have tried keeping the pdr in AC and where I load (not AC) and probs remain.

Over a good many yrs using BE I had 3 bushings bored for normal variation in lots. They are nominally 4.0,  4.15, & 4.3. I use the appropriate bushing, most often 1 or 2.  On a recent occasion it was necessary to use 4.5 gr. The bullet is a cast 160, the gun a slide mt'd AP 9000 or an UD 4-dot.

A call to alliant re the lot needing 4.5 resulted in the comment that 4 to 4.25 gr was under the min. He had no realization of the no of shooters using 3.8 to 4.2 grs I guess.

I don't doubt any of the experiences  mentioned here but have found quite a variation in SOME lots.

Ron Habegger

if its bridging due to humidity try putting one or two small desiccant  packs in the hopper, I buy them on ebay you get a couple hundred for 8-10 bucks

THanks Dave, have wondered about that but hadn't spoke w/ anyone who had tried it.
R

I use two sided tape to attach one to the lid of my measure I also put a piece of tape over the air hole in most lids, keeps powder dry and flowing good.

DavidR wrote:if its bridging due to humidity try putting one or two small desiccant  packs in the hopper, I buy them on ebay you get a couple hundred for 8-10 bucks

You mean you put desiccant packs in with the powder?

not touching powder but taped to inside of lid

I keep an indicating type packet the size of a bic lighter in powder dispenser.  Its held in place with a paper clip. Check out http://www.silicagelpackets.com