I just purchased my first shotgun, an M2 Field (American) with a 28" barrel. I'm trying to decide between Nordic and Carlson's for an extension tube. Looking on the Nordic website, their sizing chart says I can buy an +8 tube which would be flush with the barrel. Their description says this would add 8 rounds to the factory capacity (2rnds) which I take to mean that I would have a total of 10rnds? Nordic sells a kit now which includes a tube, coupler, spring, and end-cap. It does not include a clamp or follower. Do I need to buy a new follower or can I use the original follower in my shotgun?
Carlson's Extension Tube kits include the tube, coupler, spring, follower, and clamp and are currently on sale at Bass Pro/[URL="http://www.cabelas.com/catalog/product.jsp?productId=1318791&categoryId=0&parentCategoryId=0&subCategoryId=0&indexId=0&itemGUID=1eefbb91ac10a0534fd9cb1352216d8f"]Cabella's[/URL]. But they only have an 8 round tube. I'm not sure if this is equal in capacity to the Nordic +8 tube or just means it's equivalent to the Nordic's +6 size?
Also, is the Benelli OEM tube cap important to have on the tube? I heard that they were designed to be some sort tool though can't seem to find any reference to that use in the manual.