Am I damaging my breech seal cleaning the barrel?

I read some where about the tissue test. put a Kleenex over the breech and fire a few rounds. if your seal is leaking youll see the tissue move. as far as damaging the seal, I guess it depends on what you are using to clean it with. a lot of people use goo gone which is not supposed to damage the seal.

It is possible that your homemade pull-through cleaner is cutting or nicking the o-ring....this will cause the rings to prematurely fail. I did this a lot when I first started to clean my barrels.
Are you using a cleaning agent that will not damage to o-rings?
Is it possible that you are dislodging to seals when you are pulling the cleaner through the barrel?...I did this a lot too. I had too much at the end of my pull-through and it was causing the o-ring to become twisted.
If you wish to replace your pull-through, you can get one of these...cheap.
http://www.mac1airgunshop.com/jl-crown-saver-p/jlcs.htm
HTH
Mike

Even though it is a bit of a pain, I just remove the breech seal to clean the barrel. After a couple times of getting a good method down, I can pop one in and out in a few seconds.

 I use a couple of metal picks to pop them in and out of my marauders. I remember someone else responding to a post that puts a dowel rod in the barrel to help get the o-ring back in. I have done it enough times with a couple of metal picks thats its rather quick and easy. Should work fine on your bobcat.

I normally get them out with out damage but usually replace since they are cheap.