I have a 870 security tactical model which is 6+1 from the factory. I ordered a Wilson Combat 2 shot extension.
Question: The spring that is provided with the Wilson 2 shot extension is meant for standard 870 mag tubes, correct? If I am correct that the spring isn’t the correct length for my model 870, where can I buy the correct spring?
Basic rule of thumb… Initially cut the spring 12-14 inches longer than the combined length of the factory tube with the extension attached. Close everything up and check the capacity (with dummy rounds if possible). If you feel the spring binding on the last round or it won’t load cut an inch or two off at a time until it works. WEAR SAFETY GLASSES!!! If the supplied spring isn’t long enough I would get one from Nordic. It’l be a good 2 feet longer than you need.
Forgot to add… Does your magazine tube have the dreaded dimples??
Yes. It has the dimples. I’ll find the the thread on how to remove it once I figure out where to buy a longer spring. Wilson says they don’t have a spring that will accommodate my model 870 with their +2 extension and told me to return it. So I can find a longer mag spring from Nordic?..
My whole goal with my shotgun was to find a 20-21in barrel which would of looked good with the +2 ext. But having the security tactical model, the barrel “collar” is further towards the muzzle than a standard 870 barrel.
I have found that a socket that you use for socket wrenches that is the inside diameter of the tube works pretty well… I just use a hammer to press out the detents in the tube from the muzzle end
The safest way to remove the dimples is to drill them if you don’t have the proper tool to press them out. The socket method will require the socket diameter to be the exact same as the tube ID or you risk egging the tube. If you tap the socket one time to many you will really be but hurt!
http://www.xssights.com/Detail.aspx?PROD=1085847&CAT=9090
Swage tool for removing dimples.
If you already have the 6 + 1 magazine capacity–you have the factory extension screwed on to your 4 shot mag tube. You’re set to go. I apologize if I erred in reading your post.
I have no factory extension on my shotgun. It has a standard mag tube cap.