I used parkerized retaining clips that I picked up at ACE, they fit perfectly on the cylinder and you can't even tell they are there. They are also nice because you dont have to take the gas cylinder all the way off and remove the flash suppressor, and you also don't have to cut them. It's a cheap and easy way to do it well, but you can always get the shims from fulton and do it right.
My biggest piece of advice is to not remove the flash suppressor to remove the gas cylinder. It's extra work that you don't need to do. With the retaining clips, i just had to bend them and slip them over the cylinder, the same would go for fultons shims except you have to cut them. I'm sure that the other guys will give you better advice, I've only done this once and I hack jobbed it :roll: . The important thing is that it works :lol:
My biggest piece of advice is to not remove the flash suppressor to remove the gas cylinder. It's extra work that you don't need to do. With the retaining clips, i just had to bend them and slip them over the cylinder, the same would go for fultons shims except you have to cut them. I'm sure that the other guys will give you better advice, I've only done this once and I hack jobbed it :roll: . The important thing is that it works :lol: