Tuesday, August 26, 2014

Fixing my vintage air gun

One of my recent obsessions has been watching various DIY videos. A lot of them focus on making compressed air guns. Deep down there is a part of me that wants to make some, however, the sane part of me knows I would just get into trouble. This got me thinking about my old Benjamin Model 132 .22 cal pump air pistol.




I got it in the late 1960s and used the heck out of it. The last time I had used it to any extent was in the mid 80's. About a year ago I found it and thought I'd plink a bit. To my horror I found it wouldn't hold pressure. I learned you could buy kits to replace the seals but didn't pursue the issue. About a week ago, I started doing more research. Near as I could tell and without asking for a quote, the kits plus valve tools would run at least $60. That's assuming I could get it fixed and reassembled on my own. And not get a spring in my eye. I also found that a new model, now made by Crosman, can be had for less than $60. Finally, I checked what I might be able to sell mine for. In its worn condition, I'd be lucky to get $40 for it.

I found some random threads where airgun repair was discussed. They noted that the seals in these old guns were leather and they would dry and shrink if not oiled, which mine wasn't for over 20 years. Some people said they had success just oiling them heavily and letting the leather absorb the oil. There was discussions of gun oil, 10W30, and even airgun oil. I started with what I had: 3-in-1. For a few days, I'd add some oil in the lube hole, tip it on end and wait. Then I'd repeat and tip it the other way. No joy. Next, I decided to try WD40. After a day, I could get a couple of pumps before I heard it leak. That was progress so I continued. This morning I gave it a try and, to my amazement, it was holding some pressure!  I seem to remember it being harder to pump after about 10 pumps. Since I haven't gotten stronger, I suspect it may still be leaking at some pressure, although I can not hear the leak as before. So, while it may not be up to full power, it will shoot a 22 pellet through my foam target at 20'. I'm continuing the oil treatment and will make a better target.