Will a Benjamin/Sheridan hold its air charge for a long period of time? We're having a lot of trouble with pesky squirrels and I would like to keep it charged with air for those quick shots. Pumping takes time and the critters are usually gone by the time I get ready. They're chewing holes in my shops sheet rock to get at the insulation for nesting and chewing holes in our seed buckets. Also eating all the seeds we put out for the birds. I get one now and then. the dog gets one now and then, as does the cat. It's been a constant fight but the squirrels are winning. I like squirrels in their habitat, but when they get in mine, I draw the line.