BamBams is right on. If a 1911 has a properly fitted barrel and bushing, the slide assembly tends to work as a unit (sights are on the slide too). Contrary to popular belief, it really doesn't make much difference if the slide is loose on the frame. I have a perfect example in my safe. It's an old Series 70 Colt with a slide that is loose as a goose but still shoots very tight groups. I installed a new (oversized) barrel and match grade bushing that tightened the top end up like a vault.
As guns wear, the slide-to-frame fit loosens as does the rest of the gun. People falsely blame a loose slide for accuracy issues because it's something they can see and feel. The areas of a 1911 that will cause accuracy problems when they wear are: Bushing-to-slide, bushing-to-barrel, barrel-to-slide lock lugs, barrel hood-to-breach face lugs, barrel link, barrel link pin, and slide lock shaft. Occasionally a barrel bore will wear out. I have the original barrel from my Series 70. The rifling is so thin you would swear it's a smooth bore. That's what 50,000 rounds of hard ball does.
