I own a rem 1100 and use it mostly for trap.  Besides the obvious 11-87 can take 3 and 3 1/2 shells what are the other differences?  I all ready have an 870 that can accept 3 inch shells and I do not hunt.  So this is just a, what is mechanicly different between the two types of question.  I am curious because I am thinking about purchaseing a semi auto for defense type purposes along the line of my rem 870 home defense model.  I have way to much practice with my 1100 that I don't feel confident with the 870 when under high stress.  

No difference other than what you mentioned, 1100 takes 2 3/4" shells and 1187 takes magnum shells.

I understand what you're saying. I have pumps and semiauto shotguns, and in the past I have forgotten to rack the slide on a pump and I have also attempted to rack the forend on a semiauto shotgun. It's a matter of training.

I have way to much practice with my 1100 that I don't feel confident with the 870 when under high stress.

Ever consider a second defensive barrel for your 1100?

I use my Benelli Legacy in all the clay events. In fact, I fired 18 rounds of trap this weekend alone, not to mention the hundreds of Trap, Skeet, and SC rounds it's seen in the past couple years. It's became part of me, I guess.

In my search for a good defensive shotgun, I decided to just add a shorter barrel to my collection.

This is the form it takes when not on the clay ranges. I have a large Hi-Viz Turkey sight mounted on the rib for a great sight picture. Because of my familurization with this firearm--through thousands of rounds of fire--all actions have became automatic; loading, unloading, trigger control, safety, etc.

One might make arguments about the nickle reciver on mine, but you're probably going to be wearing your pagamas in a real defensive situation, so the need for a subdued firearm is sort of null.

Also, the longest room of my home is just 20ft(under 7yds), and a standard Trap/field load will do great damage on a human target at that range without the worry of extreeme overpenetration of multiple walls. I also have a few boxes of Federal's Tactical(low recoil) buckshot, but still load it with Trap rounds for home-defense.

I don't feel limited by the 5-round capacity and the gun has been 100% reliable since the day I purchased it. The barrel was a 28" that I shortened to 18.5. I also squared the muzzle with a flat-file and reblued. It looks like a factory job.

You probably have your mind made up on a new shotgun, but a second barrel could be something to consider. I always see tons of 1100 barrels in catalogs. Also, there will be no need to 'learn' a second gun.

Leader, Remington is using the 1100 platform mostly for target guns, Classic Trap, Classic Skeet, the new tactical Competition Master and three Sporting guns in 12, 20 and 28 gauge. There are four 1100 hunting models but there are at least 20 different hunting models in the 11-87 platform. Also there are four Police models in 11-87. The 11-87 has different gas rings and gas ports to handle the heaver shells. If it is going to be a tactical home defense gun you should look at the 1100 Competition Master or one of the 11-87 Police models if you want to stay in the Remington family that you are familiar with. MIKE.

The main difference b/w the 1100 and 1187 is the 1187 has a self regulating gas system that allows you to change b/w 2 3/4" shells and 3".

In the 1100s, you had to change barrels. Not only for chamber length, but also for the gas ports. The 1100 2 3/4" has 2 ports and the 3" has one. Makes sense. You don't need full 3" pressure to cycle a gun whose action is set up for 2 3/4" shells and pressures.

The 1187 Premier accomplishes this by adding 2 gas bleedoff ports at the front of the barrel hanger {that's what I always called it}. When the gas pressure becomes greater than what's needed to cycle the action, the excess gas is bled off through these ports.

EXCEPT in the 1187 Police. For some reason, they do not have these bleedoff ports.

Thanks,
Lee

So on the 1187 I would have to change settings inside the gun if I was going to switch between magnum rounds and regular 2 3/4 shells?

No. It is "self" regulating. Only as much gas as necessary reaches the piston. The rest is bled off.