by Hoot » Thu Nov 09, 2017 9:59 am
Welcome aboard OM;
There are many things we could check but first, give us a rundown of the components you used in your build.
IE:
Were you using factory ammo?
Barrel make, model, gas system, surface treatment
Receiver make, model, conventional or side charging, surface treatment
BCG make, model, surface treatment
A1 or Carbine lower, make and model, type of spring, type of buffer.
Anything else you can think of.
Without knowing that info, the first question for me would be if you ease the bolt forward without a round in it, does it slip into battery w/o using the FA? IE does it only happen with a cartridge in it? Does it happen with the last round in the mag? Does it happen with several different mags? Do you have another AR on hand? If so, does the 450b upper function better using a different lower? These are the beginning questions on a branching troubleshooting tree. Cleaning is always a good discipline but running the action wet as well is often necessary on a new build to help it cycle until the gliding surfaces are polished up. Running them wet also helps transport the liberated grit from the surface treatment away from the gliding surfaces, where it can be wiped off during cleaning. Compressed air works also as long as you're not driving the grit further down into the cracks and crevices. Obviously, parts that have a specialized surface treatment such as Melonite, Nitriding, Nib, Chrome, or other friction reducing properties, reduce the time it takes for them to smooth out. I know members here who have sat watching TV and repeatedly cycled the action in and out, by hand, to polish up the gliding surfaces. The standard phosphate (mil spec) finish can have a pretty abrasive surface when its new.
Hoot
In Theory, there is no difference between theory and practice. In Practice, there is.