I bought the lock for a Mossberg 500. The three 10-digit keys rotate smoothly, and adjusting the combo is easy with the included T-tool. When locked properly, the lock allows zero motion in the trigger compartment (it is also completely occluded by the lock's body). The lock sometimes sticks, requiring a bit of finagling to remove, which is why I rated it a 4 overall. However, I am very happy with my purchase (especially for the low price).

Fits great on my AR. This was the first combination trigger lock I have been able to find and it didn't disappoint. Has an button that is used to easily configure your custom combination. Will be buying more.