If your gun has the dimpled mag tube and plastic spring retainer, you could just take off your mag cap and screw the +1 extension right on (using the included wave washer if needed), leaving the factory retainer, spring, and follower where they are. This'll give you the extended cap you're looking for, and the magazine will function exactly as it did with the mag cap. Obviously you'll want to get that extra round at some point, but this'll let your gun keep serving until you get around to getting the dimples removed.
870noob wrote: ↑Thu Nov 16, 2017 3:34 am
@Synchronizor - this build is for home defense, so may I ask which type causes the least problem with feeding, etc... thanks
Any good extension should work reliably if you install it right, but +1 extensions are nice because they're mostly just there to make room for a longer spring to coil up into. The base mag tube has enough space for 5 typical 2.75" shells and a follower, so you don't have to worry as much about stuff hanging up in the joint between the mag tube & extension.