Q: The 7 round extension does not add 7 rounds to my capacity, it appears that the spring is in the way?
A: The extension will add to the already existing capacity of the shotgun, increasing it to a total of 7 rounds. Keep in mind, capacities include one round in the chamber. The 8 shot and 10 shot extensions will increase the total capacity to 8 or 10 rounds.
Q: Is there a maximum barrel length recommended for these?: Yes, recommended maximum barrel lengths are as follows:
7 shot extension 18" barrel
8 shot extension 20" barrel
10 shot extension 26" barrel