Most of the newer Extended Range is a bit softer than most other high density shot. If you notice that your choke tube seems to be very difficult to remove from the barrel after you shoot, than that would be a big indication that you may want to consider either a different load, or a different choke tube.

You may notice that you can see excessive plastic buildup inside your choke tube. Look also at your fired wads, if you can find them. If the pellets are cutting through the wadding, or very nearly so, then you have overchoked your shot load. You'll notice more flyers due to deformed pellets. You may also get irratic patterns, that vary greatly from shot to shot.

You may also, in more extreme cases, scratch the inside of you bore/choke tube. In the most extreme circumstances, you'll bulge the barrel or even burst it (though I doubt with a reasonable constriction, even in a lead only choke, in a modern firearm in sound condition this would ever happen without some other barrel obstruction).