I've shot 1100 and 1187 for 3 gun for a lot of years... the 1187 extractor is considerably larger than the 1100...you get a stainless mag tube also with the 1187...if you are looking at an older 1100 ... get the single piece gas ring... if you want to shoot light loads, the 1187 21" barrel does not have the gas relief ring, and acts like a 1100 barrel...you may need to open up the gas ports with the shorter barrels to get them to work...I never had a cycling problem with anything larger then 3 dram 1 1/8oz... I shot the 1100 for 5 years for the Chevy STC and it saw a lot of shots for practice, and a lot of parts broke...mostly the bolt carrier link (tuning fork) but lots of the smaller pins on the shell lift, an extractor or two and one early gas ring..... if price is not a consideration, I would opt for the Benelli M1S90....I shoot a 21" field grade M1S90 for 3 gun now...compared to the Remingtons, the bolt carrier link is massive, and the trigger group has minimal parts.... the key to making a Benelli run is to make sure you have a good magazine spring...at least 13" longer than the tube for the shorter gun ( I shoot a 8 +1 mag tube)...for cold weather, don't add a lot of weight on the Benelli... it is inertia driven.... with dimensionally correct shells, my Benelli also runs well with 3 dram 1 1/8oz promo loads... before finding out the spring requirement, at 26F and a full side saddle it was not 100 per cent with low recoil slugs
22 slugs at the house clearing FB3G 2010.... and it was cold...