Just an FYI, but there is no way a piece of glass is making it thru the filter on the needle into the syringe. I basically used to just put the amp in a plastic baggie and hold it from the outside (to prevent glass on floor and counter) and I would just smack the amp head with a butter knife. Sounds nuts but it was sure fire that the head would pop and no juice would be lost. Never had a spill at all, which I couldn't say for snapping the amp. With this method, I'd f-up every blue moon. I open with an opener now, but my main point was there would almost always be broken glass in the amp, but it would never make it past the filter on my drawing needle. Only worry you might have is if you draw and shoot with the same needle as some could be needle side of the syringe. Who uses the same to draw and shoot anyway though?