What is the point of ribs?

[spyder1911]

I am a recent convert from the rifle/handgun world. I am soon getting a shotty for trap and know that vented ribs are among the features commonly recommended.
What purpose do ribs serve?
What is the difference, other than the obvious physical difference, of vented and regular ribs?
I realize these are stupid questions, but if I never ask I will never know

 

[41magsnub]

As I understand it some competitive shooters were tired of the heat mirage effect screwing up their vision. I'm probably wrong.. all my shotguns have them. I've shot shotguns without them and it really makes no difference to me.

 

[RNB65]

Actually, it's a great question.

Trap shooters use ribs so they can adjust the majority of the shot cloud to be above the bore axis. But for other types of shotgun shooting (hunting, skeet, sporting clays, plinking) ribs serve no real purpose whatsoever. A rib may have some minimal peripheral vision benefit, but mostly they're just cosmetic.
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[foghornl]

If you shoot a lot over a short time period, the 'mirage' effect due to heating of the plain barrel can be an issue.

Also, some folks say the vent-rib on the barrel helps them pick up the 'sighting plane alignment' faster. Never had a vent-rib barrel, so I don't know it it works for me or not.

 

[SDC]

They act both to dissipate heat and to guide the shooter's eye towards the beads and target, so that if you're not mounted on the gun properly, you will pick up on that imediately. Having the bead sit in the middle of a wide rib acts almost like a "ghost" rear sight, because if you put the shotgun up and if your eye is off too far to one side or the other, it stands out.