Has anyone noticed whether 777 looses it's efficacy over a year or two?? I had a problem with some 777 over a year ago, it was clumping up. I have a bottle left over from last year, and it seems like the powder has lost some of its OOOMMMPPPHHH!! Is this possible??

I have stored and used smokeless powder, andblack powder in the past with no problems. Some for quite a few years. But this 777 stuff seems different. Tom.

Efficacy, now there's a word I was not expecting to see on the BP forum.

Anyway, I know that certainpowders, once opened,do lose power over time. Humidity is especially bad for certain powders that are "sugar" based.

I don't know about 777, but I'm sure others here do.

Right now I am shooting some Pyrodex that is several years old, but only opened last year. I use some plastic wrap under the lid and screw it on tight for storage. No issues with power yet.

It's my understanding that 777 is hygroscopic which means it will absorb water. To me it seems like water would reduce it's efficiency.

If it isn't sealed tight enough it can absorb water and lose power. Normally mine is fine but I did have a bottle do that one time.

Have a can of 777 that was opened in 2005. Opened that can and it got misplaced while i used up anotherseveral othercans of 777. The lid was kept tight. When i last fired some of it in October is seemed as stout as ever.

777 is hygroscopic , [absorbs moisture ] though there are other powders that do it a lot worse. When a powder absorbs moisture it will change the burn rate which can affect accuracy. This should not be a problem if it is an unopened can or kept properly sealed. Before I switched to BH209 I used to keep it in my gun cabnet if it had been opened because there is a dehumidifier there. Lee

Sounds like some moisture has gotten in and the 777 has absorbed it. When that happens, you pretty much need to throw it out and buy a new can.

I've had cans for 2 or 3 years that are still okay. I follow these steps for storing powder, and it seems to work:

1. Don't store it in a moist environment- like a basement. Store it somewhere dry, or put it in a air-tight box.
2. Don't keep the lid off for any longer than you have to, then make sure it is very tight putting it back on.
3. I put 2 - 3 silica gel packets (they absorb moisture- they come in the packing of various things) in the bottle, then change the gel packets once or twice a year.

I haven't had any problems when I followed this list.

When you mentioned it had clumped up.. that suggests to me it absorbed moisture in the air. Like mentioned there are some powders a lot worse. I have stored open powders. The trick is to keep the lid on tight and put them in a room that is not too humid. Although once they are open they don't last too long around my place.

I have had some on hand for almost an year. never had an problem. I keep it in an room that stay around 65 to 75 all year round. had an can for about 3 months with nothing but the spout on it. no clumps. really did not see a lost of power.

yep and thats why i no longer use the stuff. Just not reliable from one outing to the next.