If they set the trigger.

I have a couple 687's from the mid 90's, one each in 12 and 20.

I've not tried any light 20's, but in the 12 if you load an ounce, it needs to be a pretty quick ounce to set the second trigger.

My 682 doubles trap gun is the same way, it likes a bit of a thump to set.

I do plan to try the Beretta 20 with the light load, but my hopes are not high.

Of course, this is nothing Rich Cole can't remedy for a buck and a half a gun plus shipping each way.

"The price of good shotgunnery is constant practice" - Fred Kimble