Is there any difficulty in switching out the railed handguard to a standard handguard on the SIG 556, specifically the patrol model?  I found a railed patrol for a good price, and I know the patrol handguard and front cap are available at Colorado Gun Sales, just wondering what all needed to be done to swap them (i.e. do you need to remove the gas block?)

Thanks!

The factory SWAT rails come off very easily with no tools. But, yes, it looks like the gas block must be removed in order to get the new retaining ring that the plastic hand guards will require installed:

http://www.mfiap.com/smallarms/sig-552-hg-instructions.shtml

I was looking at doing the same thing with a SWAT Patrol. But after I learned all the trouble (and cost) one would have to through, I decided the factory rail would do just fine...

Scored a Sig 556 patrol with a standard polymer handguard for a good price, so it is a non-issue, but thank you for the link!