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ByronF
February 24, 2017, 19:40
Finally received my 10.5" upper. Kind of an oddball in that its a regular M4 upper receiver with deflector hump, port door, and forward assist. It has a rail, but under rail the barrel has a gas block shoulder at carbine location.

The bolt dragged against the ejector. Rather than shim I just put a little dogleg on it using two adjustable wrenches (remove it so you arent prying against the notch).

Bolt seemed rough when hand cycling so I polished the bolt sliding surfaces. Was still rough so I also polished the pinned-on weight at back of the bolt, which was roughly turned. After that it still feels like a vinyl record. Makes "zip zip" sound when cycling. I suspect it may be texture inside the KAK Shockwave tube.

Fit of PSA upper to PSA lower is snug.

Mag catch nub that engages mag notch (Glock lower) was unnecessarily long, and with no taper to the bottom edge so I needed to press the button to insert a mag. I shortened the nub quite a lot, which reduced the effort and length of push to release a mag. I also be eled the bottom edge so mag can be pressed in easily.

Although this lower does not have the LRBHO feature, it does of course have a bolt catch that can be manually actuated. But the engagement with bolt is so minimal that I have to pull out top of bolt catch button to engage. And just barely. Maybe a little metal removal from bottom inside of catch will allow it to rotate further to engage bolt better.

yellowhand
February 24, 2017, 23:45
I got one a while back, standard 16 inch rifle model.
Slapped the upper and lower together, made sure barrel was not plugged and ran 300 rounds through it without cleaning of any kind.
Was rough when I began, smooth when I finished.
No FTL/FTF/FTE and has been rock steady reliable ever since.
Wify loves it.:)

hkshooter
February 25, 2017, 10:57
I started a 9mm project, turned into a PITA so I back burnered the thing. Will start over again with a dedicated UZI mag lower at some point.

yellowhand
February 25, 2017, 13:12
I started a 9mm project, turned into a PITA so I back burnered the thing. Will start over again with a dedicated UZI mag lower at some point.

My psa one went together fine,got it for Glock mags, had a lot of those.:uhoh:

hkshooter
February 25, 2017, 18:53
My psa one went together fine,got it for Glock mags, had a lot of those.:uhoh:

My project started life because of the "great deal" PSA had on the adapter blocks. Which turned out to be shit. Hence my decision to use a dedicated lower should I decide to pursue the project again.
The little bit of PSA stuff I've used so far has been great but for the adapter block.

yellowhand
February 25, 2017, 19:57
My project started life because of the "great deal" PSA had on the adapter blocks. Which turned out to be shit. Hence my decision to use a dedicated lower should I decide to pursue the project again.
The little bit of PSA stuff I've used so far has been great but for the adapter block.

I did the dedicated lower myself, started to use the adapter, but have never had good luck with any adapters on anything.:D

ByronF
February 26, 2017, 16:46
Further analysis: firing pin retaining pin looks like a common cotter pin snipped off roughly with a dull pair of dykes. And the round end is above flush to the bolt body, so was dragging inside the receiver. Stoned the end to a taper, and smacked the round end with punch and hammer to knock it below flush.