Originally Posted by Worldofpaintball
What do you mean by breaking them in? Won't they swell over time? Example monkeyoring kits
No, o-rings don't swell unless you use dow55 or a lube that has petroleum in it. Regular buna o-rings with a dow33 based lube will not swell...they will actually get a little smaller as they break in as some of the outer material works off over time.