Got the new gun and barrels today. It seems when I install the barrel there is a slight gap 1/32" ( yes that small) between the top rib of the gun and the rib of the reciever . Same thing further down the gun, the magazine has a very small gap also 1/32" when the screw is fully tightened to the barrel.... now all other shotguns i own when the barrel goes in the top ribs mate together and blend as one....not having a small gap. Or any .....upon looking in the receieve it appears the barrel is bottom out but on the outside the barrel-tube and the battel rib to receiver rib have a small gap..?? Any thoughts or is this normal for a 500

Yes that gap is normal on both the 500 and the 88.

The barrel should bottom out on the tang inside the receiver. Any gap b/w the rib and receiver or lug and mag tube is perfectly fine.