I bought a total of four units—one for myself and three for friends. The unit I used has a loose bolt issue: when the breech is closed, the bolt assembly remains loose, causing movement between the breech and the bolt. This likely leads to air leakage or prevents the hammer from striking the valve correctly, resulting in muzzle velocities of only 400–500 fps. This happens consistently when the bolt is pushed forward; if it is locked in the rear position, velocities stay in the 930–950 fps range (using 15-grain pellets). Now I’m worried that the other units might have the same defect, and I won't be able to return them since I brought them all the way from the U.S. to Mexico!
The rifle feels solid and lightweight, and it comes with plenty of spare parts; it also included many bonus accessories, and the packages arrived well-protected, which I appreciate. However, I would also appreciate your help in resolving the issue I mentioned.