Leaving powder in the powder measure

I was reloading today and had a goal of loading 400 rounds.  When I completed 163 rounds I was unexpectedly interrupted.  My intention was to take care of the interruption and pickup where I left off in about 90 minutes.  I cleaned up the bench but left the powder in the powder measure.  Things didn't work out as planned and I didn't make it back to bench and I likely won't until Monday.  Is there any harm in leaving the powder in the hopper?  I only own 1 type of powder, BE and I have a desiccant pack hanging in the tube with a paperclip.  Is there any downside to leaving the powder in the powder measure?

In some cases the powder can begin etching the powder measure plastic tube and sticking to it. Based on what I've read this has something to do with a reaction from the nitroglycerin in some powders but I am no chemist so I can't say for sure. In my own experience I have left powders in the measure for weeks on end with no ill effect but I typically load with N310 or W231. I have a friend who never empties his Star's, he just keeps topping off the Bullseye as needed. If I had to guess I'd say those powder measures have been exposed to Bullseye powder for the past 20 years; he is a very active shooter.

I recall reading (many years ago) that powder left in a measure can become degraded fairly quickly if exposed to sunlight. This would have been written back in the 'Skeeter Skelton' days and the article described his less than impressive 'cow killer' loads. There being little to no sunlight reaching my reloading bench I have never tested it. I do empty my measure unless I will be continuing the current project within 24 hours but can not offer any reason that it has to be done.

Bruce

As long as the powder remains dry, it doesn't seem to do any more harm than turning the "glass" yellow. I've been lazily doing this for many years. This may not be a good idea if you live in a high humidity climate and your reloading equipment is exposed to it. BTW, I label the powder measure with masking tape, indicating the type of powder and the last charge set. I still weigh a good sampling and adjust as necessary before starting the next reloading session.

Never had an issue until loading W super handicap in shotgun shells. Over an extended time it caused the plastic hopper in my 366 to swell and discolor.

Never a problem with wst, 231, or be.

my powder stays in the hopper all season, I do however put a piece of tape over the air hole in the lid and I tape a small desiccant pack to inside of the lid, never had a issue except when I didn't do this over a long time bullseye powder did effect the plastic tube some and discolored it some.

BE Mike wrote:As long as the powder remains dry, it doesn't seem to do any more harm than turning the "glass" yellow. I've been lazily doing this for many years. This may not be a good idea if you live in a high humidity climate and your reloading equipment is exposed to it. BTW, I label the powder measure with masking tape, indicating the type of powder and the last charge set. I still weigh a good sampling and adjust as necessary before starting the next reloading session.

Same experience here. I regularly leave powder (TG or 700X) in the measure for maybe 4-5 days and have not seen any reaction or inconsistency in my loads. Some years ago I left some (Unique) in the measure for a month or so and it did discolor the hopper so I dumped that and cleaned everything before loading further. That was in CA and not a high humidity area or exposed to sunlight.
                                         Cliff

Hi Don, some powders don't just discolor the plastic tube; they will MELT that darned tube!

Bullseye left in my Redding # 3 plastic reservoir really did just that.  The reservoir bulged

near the bottom and melted significantly out of shape. 

Tony

tonyg wrote:Hi Don, some powders don't just discolor the plastic tube; they will MELT that darned tube!

Bullseye left in my Redding # 3 plastic reservoir really did just that.  The reservoir bulged

near the bottom and melted significantly out of shape. 

Tony

I've had the same thing happen with a Redding powder measure and BE too, but have left BE in my Dillon for 4 months now and there is no damage of any kind. Must be different plastics with Redding and Dillon.


Virgil

I have powder in the hopper all the time; mostly Bullseye.  Have never seen a problem with Dillon or Redding powder measures.  Been doing it for many years.

Interesting, I'll keep an eye on it.

My Lee and my Dillon have Bullseye in them 24/7/365 for the last few years. No degradation

Something to consider.  One of my fellow shooters never emptied his powder cylinder, only filling up. This practice continued for over 35 years. Finally one day he had nothing but squib loads with .38 special HBWC. Some bullets exited the barrel, others were stuck at various lengths of the barrel. His examination of his reloading equipment revealed his powder drop was significantly clogged similar to a clogged sink drain. He was wondering why he had to increase his drop adjustment recently. He ended up pulling over 500 rounds. Now he religiously empties his powder cylinder after every use.

I have had spiders build a web in the drop spout and have to clean them out but never just a clump of powder.

humidity, powders enemy...

tonyg wrote:Hi Don, some powders don't just discolor the plastic tube; they will MELT that darned tube!

Bullseye left in my Redding # 3 plastic reservoir really did just that.  The reservoir bulged

near the bottom and melted significantly out of shape. 

Tony

Very similar experience with my Hornady. 

Brian

I use a Hornady electronic powder measure and I left BE powder in it overnight. When I finished that loading sequence the next day and emptied the remaining powder, I noticed powder sticking to the bottom of the powder measure. It could not be dislodged. The plastic cylinder also became discolored.
I contacted Hornady tech department and was told that they had received many similar complaints, but had no real explanation. However, the tech advised that I use a "dust buster-type sweeper" to get all of the residual powder out of the hopper and do not leave powder in the measure even overnight. One of the first rules I learned about reloading was to never use an electric sweeper around powder or to even use one to clean up spilled powder. Shortly after that episode the powder measure quit working and I returned it to Hornady for repair, but about 10 days later I received a new powder measure as replacement. Now, I thoroughly clean the measure after each loading session using "canned air" typically marketed to clean computers and cheap at Wal-Mart.

my powder tubes over extended times with bullseye, did discolor, the hornady even deformed but once I added the desiccant pack and closed off the air hole that all stopped