Anyone know or have used a 1187 barrel in a 1100?

They are not interchangeable. From Remington:

 

Question

Can I fit my Model 1100 shotgun with a Model 1187 pressure compensated barrel and shoot both field & magnum loads?

Answer

Although the Model 1100 and Model 1187 shotguns are very similar in design we do not recommend that the barrels be interchanged between models. The extractors and corresponding extractor cuts in the barrel extensions differ. The locations of the barrel seal grooves in the magazine tubes are in slightly different places. Most of all it is an unsafe practice to exchange parts between models unless it is a documented fact that the different models use the same parts.