New PSA Glock 9mm AR build and issues

[Sharpie443]

So I've nearly completed my AR 9 pistol build.

10.5" PSA 9mm upper
PSA hybrid 9mm bolt
PSA Glock compatible lower
Delta tactical 4Lb drop in trigger
Blade brace (Will do the paperwork to SBR it this year)
Vortex 2MOA red dot

I like it so far but I do have an issue with the lower. The last round hold open just dosn't work. A friend of mine built the exact same gun and has the same issues. Everyone I've talked to can't seem to get it to work properly and after having a look at exactly how it supose to work I don't think it will ever work properly.

With a 5.56 the mag interacts directly with the wedge when empty and only needs a little bit of force to pivot it up. The Glock mag has to apply upward force on a 2.5" bar to pivot the bolt hold open to the side against the force of another spring. Just not enough spring pressure or movement distance for that to work with a Glock mag. Your trying to turn 1/8" of movement into 1/8" of movement in a different direction on a different pivot point 2.5" away. The physics are not with PSA but at least they gave it a shot.

Still happy with it all the same.

 

[wally]

Sounds like it is supposed to work the same way the one on my QuarterCircle 10 lower does. It needed a lot of futzing around to get it to work but its been reliable since. Two main things I did was to polish the BHO to make sure it didn't rub anywhere on anything and then I started grinding turns off the BHO spring until the Glock mag could exert enough force to overcome it. I'm pretty sure a "standard" BHO spring from a 5.56 LPK will never work.

You have to pay particular attention to the BHO area when cleaning to keep it working. We'll often run a dozen 33 round mags (loaded to 30) through it when shooting suppressed and they pretty much always lock back on the last shot.