I have the mbx, I’ve shot 3500-4000 rounds and haven’t had any issues. I will say read the instructions on tuning the buffer and about break in. It’s set up really nice from Adrian, I’ve changed three things 1) ambi charging handle 2) a ctr stock with a fang 3) magpul moe grip. I’ve been shooting 147gr rn with 3.2gr of titegroup cci primer mixed brass. It’s kind of sluggish so I’m going 124 fmj with 3.6 to 4.0gr titegroup cci primer mixed brass. Adrian has answered any questions I’ve had usually under 24 hours from time I sent the email.
