am always worried about using foaming cleaners on any gas operated rifle, no matter if its a rem 7400, BAR, or AR-15.
I can see the potential for problems with gas piston rifles, AR-15s I don't worry. I prop the upper upright so that the foam runs out of hte gas tube and not down into the gas tube as it liquifies though.
You can also hit the gas tube with some compressed air if it makes you feel better.
