A&K Nozzle and Piston Set for A&K M870 Spring Powered Shotguns

"I purchased this to fix my G&P M870 since G&P set is never in stock and it has a metal plate on the bottom which will not break like G&P version did on my shotgun after only shooting it about 20 times. . I finally received this product and was happy to put it in. I opened up the package and it felt sturdy and fine. I knew the first test was a compression test to make sure it works correctly before i even think about installing it. I am glad i did because it failed badly. Didn't even hold any air at all. I thought it might be a bad o-ring and replaced it and that did not work. its more of a design issue. So i tried something. I used my G7P piston which was fine but used A&K nozzle which I wanted because of the metal part on the bottom. I did a compression test and it worked great. Tried it a bunch of times and was happy with the result. Now all i had to do is install it in shotgun. I found one problem in installing it. The metal Nozzle part on the bottom was to wide. I had to trim it to make it work in the G&P M870 shotgun. Once I got it right, the shot gun works Great. I took it out yesterday and it preformed wonderfully. I was actually surprised that it worked as good as it did. I was ready to give up on it.
My opinion for this item if you decide to purchase it is to do a compression test on it first. Also the Manufacturer needs to make a better design for the o-ring section to give it a better seal. To big of a gap between Nozzle and Piston.