Apparently there is a small port in the barrel of a BAR the lets the gas into the gas system. Do you think using wipeout (or other cleaner for that matter) would be a problem over the years for the gas system??

I hope not, I've been using it in my BAR's and HK SLB for several years. No ill effects that I know of.

As routine maintenance you should take apart the gas system apart for cleaning, as far as fouling the pressure hole in the barrel I wouldn't worry about that since it is exposed to extreme pressure however on the two BARs that I own the piston and related parts do get dirty. I have never had a malfunction but maintenance will minimize that. Prior to my BAR I had a rem 742 that ripped the rim off a 30-06 shell and left it in the chamber. I was told tat was attributable to a dirty chamber?

When cleaning any gas operated rifle it is always recommended to keep the rifle upside down to keep the bore cleaner out of the gas system, if you don't intend to clean the gas system completely. Since the Fowl Out is probably going to migrate into the gas port no matter how you have the rifle, it would be recommended to clean out the gas system, since gas systems should be kept dry. The BAR is a great choice for a gas operated rifle.

I used Wipe-out, and now GunSlick in my AR10 with no problems what so ever.

I have been using Outers Foaming Bore Cleaner in my AR. After I patch out the bore cleaner I Put compressed air through the gas in the upper receiver. The basic air chuck that came with the compressor fits snug and blows anything that might have gotten in, out.