Got it figured out. Attach the coupler first without the extension. Insert the original spring because you really don't need the other one. Then put the spring cap inside the extension and use a dowel to seat it all the way down. Attach the extension to the coupler. Attach barrel and screw cap. Conduct function check of firearm. Load 7 rounds. Took to the range the next day and went through a box of target rds in no time.

Installation is actually somewhat simple however, the 6th round barely gets loaded and then if it does get 7 inside it seems like the spring doesnt help with the reloading at all. Had a few rds get stuck in the tube. Considering returning.

Product works perfect!

Threads are exposed when it's all tightened and it's super finicky getting it to fit the full 7 rounds. Had to mess with it a few times in order for it to work.

Works beautifully, needed a little silicone lubrication and I removed the spring loaded tube cap and just use the screw on and didn't have any problems excellent product.

it only allows 1 extra shell not 2, a bit of a bummer. look is great but it just doesnt allow for the capacity its advertised at

Fast shipping. Arrived in 4 business days. Extension is made of a high quality material. Easy to install. Two small problems. I only gained 1 round with European made shells. American shells, I gained 2. The other is a cosmetic issue. The coupler on the extension does not fully thread to the magazine tube leaving some threads exposed. Purely cosmetic however.

easy to Install but couldnt load 7 shells no matter what I tried

Highly recommend this simple addition!