Matrix blemished receivers

[beeks]

I received mine this past week.  Overall I'm quite satisfied.  The only blemish I can find is on the side of where the front takedown pin goes.  It kind of looks like they squeezed it so the upper and lower would fit together tighter.  I'm a machinist, I've seen this technique before.  It doesn't appear that they squeezed it much.  No complaints there (since I knew it was blemished before hand).

 

The clearance between the upper and lower where the rear takedown pin is installed is definitely looser than my other DPMS style receiver.  I am pretty new to the AR so I'm not sure how much clearance there should be, however I'm guess that in a perfect world there wouldn't be any clearance.  Just a snug fit. 

 

I'd like to know if the upper or lower is the cause of the extra clearance.  I plan on massaging the receivers to fit better.  I'd like to address the half that is the problem.  Would anyone know what the dimensions should be?  or how much clearance there should be? 

[blue109]

Can you take the slack out with the adjustment detent? I ran mine all the way down just to check and it was still pretty solid. Rock solid with it adjusted right.

[jtallen83]

I noticed my set would tighten up if I squeezed it together even with the takedown pin in. My first thought was to see if the Armalite oversized pin wouldn't help take up the slop;

 

https://armalite.com/shop/ar-10-take-down-pin-oversized/

 

Problem is I don't want to spend the money without seeing the specs on the pin....maybe Armalite will finish updating the site one of these days.

 

EDIT: I found the numbers below on the page with all their pins directly underneath it,

https://armalite.com/product-category/lowers/lower-receivers-parts/

does these mean anything to anyone, I'm not sure if they mean they taper from one dimension to the other or is this the normal size and the oversize? Still can't find a length but then I guess I can measure the one in my AR-10 when I get home.

Diameter: .277" - .291"

Edited July 30, 2015 by jtallen83

[beeks]

I haven't purchased pins yet, but the diameter of my AP pins fit nice.  They are too long though.  The play I'm concerned about it side to side or along the axis of the rear pin.  I'll have to look into the adjustment detent.  How do you know if it's adjusted properly?

[jtallen83]

Mine is adjusted so I have to put downward pressure on the upper to push the pin in. It then holds the upper pretty snug unless I squeeze. I don't have much for side to side play. I would think a tighter fitting pin would prevent some of this side to side movement.

Here is the response I got from ArmaLite when I asked about the oversize pin specs;

 

"The only specs I can give you is that the EA5101 AR-10 oversize takedown pin is 1.18" long and the OD of the pin is .277"-.291". We do not hand pick these for OD size before shipping.

Tim Rooker
Lead Tech / Customer Service
Armalite"

 

This seems like a big variance in sizes of the pin when one is looking for that perfect fit???

[Malig8r]

My set is also set up so that you need to put downward pressure on the upper to push in the take down pin. The fit is exceptional with little to no visible light between the upper & lower. I am very pleased with it. As a side note I did puchase the LPK from Chris to go with the matched set.

[blue109]

Same here. Matrix lpk. No side wiggle. No vertical wiggle with the detent adjusted. Very tight fit. Front ears are definitely tight. Feels like I'm scraping the anodized off every time I open the gun up.