For years now, I've been struggling with T-50 staplers. I've got a heavy duty manual one and an electric one and have used them for upholstering. Well, I finally got the bright idea that maybe, there was a pneumatic T50 gun available. After a search, I found a Surebonder 9600A, Heavy Duty Staple Gun and purchased it on Amazon.
I just want to say that this inexpensive little gun is exactly what I was looking for, all this time. It works like any other nail gun, when it drives the staples. It won't quite drive long staples into white oak, but only because the staples just can't penetrate the hard wood and they end up deforming, however in pine, plywood and hardboard, the gun seems to have no problems at all, driving my longest staples.
Just wanted to pass this along to anyone else who has gone thru the frustration of unsuccessfully driving T50 staples.