Is there a LPK specific to an AR-10 (actually DPMS) lower? I built this when still in California and used a regular .556 LKP with the bullet-button, not the standard mag release. The mag button fit just fine. I've removed the BB's. The .556 builds work fine but I have run into an issue on the 7.62 lower: I can only get one complete turn on the on the Mag Release and am not comfortable. If there is a specific mag release for a 7.62 version where the threaded part is about 3/16 longer I would buy that.