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Shopping for my .308AR build based on Matrix Aerospace upper/lower


ARdentFan

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Ardent   here's a good place to start..they have decent pricing      http://www.jsesurplus.com/standardriflelengthgastubewpin.aspx

:) Wash

 

Oh lemme spend some money for you...dont get that plain ol tubular handguard

try one of these...make sure its the right height    http://www.jsesurplus.com/midwestindustries308ss15dpmsloprokeymod-1.aspx

 

 

and Mid West goes on the upper without drama   :) Wash

Edited by washguy
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Thanks for the link!  They have some great prices on other parts I need.

 

As for the handguard, I like the style (its not "overly tactical" imo) but it says its DPMS when I need an armalite barrel nut. :(

 

Either way, I'll be ordering a few this and that things from them for sure!

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  • 3 weeks later...

Bought the Matrix set from Chris on Gun Broker.  Arrives tomorrow.  Just ordered the LPK from Chris.  He assures me no modifications will be required.      I paid $200 for the set, and $25 for shipping.  The cheapest lower I had priced was $180 but I was just starting to look.  In other words this combo sounds too good to be true.  We'll see.  Now about that BCG and barrel.......??  16" barrel, rifle length gas tube......smooth as silk BCG......am I dreaming?

Edited by taffrail
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  • 3 weeks later...

I went with a 18" Mega Arm's barrel and Red Barn Armory BCG. The combo was $400 at Red Barn, I will say that I couldn't find any info on the quality of the Red Barn BCG's though. It looks well made, but work has been crazy and I haven't had time to finish the rifle and test fire it so I can't comment on functionality yet.

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I to have the Matrix set up of the upper and lower i bought of GB. I also ordered the 18" barrel that AIM surplus had on sale and purchased a dpms compatible bolt to go with the barrel. Putting the lower together wasn't a big problem until i ran into the same problem everyone has of the spring being to short for the rear take down pin. 

 

The problem i've ran into is after tightening the barrel on and checking the head spacing with a round (i removed the firing pin first) the bolt will not close completely. Barrel is flush on the inside and the round seats good but the bolt will not close all the way in the receiver.

Any ideas what i might be missing as i think my brain has shut off for the moment and gone blank......thanks in advance.

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Put the firing pin back in and borrowed a head space gauge and as i see it, the bolt is about a 1/4" shy of locking up completely. If i take the gauge out the bolt slips right in......never have had this happen on a build before.,....

Did you remove the ejector and extractor from the bolt before you checked headspace?

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Also, make sure the BCG, the barrel extension and the inside of the upper are lubed up real well, if they are dry 

you can run into problems like you are describing - mobil 1 worked well for me <thumbsup>

 

edit: check the chamber to be sure there isn't any dried up machining oil or residue from manufacturing causing it to be to tight.

Edited by guruofhotrod
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 I check HS with the Bolt & Barrel Extension dry or at least wiped dry . Most HS gages you can keep the Extractor in, but the removal of the Ejector is mandatory to test with light finger pressure  , they have a grove for the Extractor & it helps in removing the HS gage from the chamber , still others are made to accommodate those components & they will need no removal .

post-11255-0-72041400-1436103490_thumb.j

 

  What HS gage did you use , " NO GO " , " GO " , "Field " ? 

  Are you sure the HS gage is good & proper Gage, we have seen bad gages here before . Believe it or not , it doesn't take much to damage a HS Gage . 

 

  Another thing I have seen is , some NIB coated Bolts are real tight & require break in to test correctly . 

Edited by survivalshop
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I used a "go" gauge to test and it was with the bolt complete. I'll take the extractor off and oil it up as after reading more post on here i'm thinking that could be some of the problem. I think i'll scrub everything good and then "dip" the bolt in some synthetic oil i have and try the "go" gauge again......thanks again for all the suggestions and help..

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  Its the Ejector that will add its spring pressure to possibly give a false reading . You can take both out if you want , use a slight tap with a cleaning rod that is made of a soft material ( aluminum or Brass ) , if the HS sticks in the Chamber

  Adding thick oil can also give false readings , it takes up space also & the thicker the lubricant is the more space it will take up . Its all going to be a tight fit when in a new unbroken action .

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I tackled the Matrix takedown spring area this way - cut a second spring and stacked them.  i should have used a small washer to separate the two springs, but can't find a washer small enough.  I doubt the springs will connect (spiral together at the ends) based in the amount of movement there is there.  If they do, it's not a big deal, not a high-risk area.

 

I figured I needed the spring to stick out as much as it does on any other AR15 build, which is about this much:

 

M1_zpsfwqiytwg.jpg

 

I stacked the two springs together (detent and takedown pin in place), and just cut it off there.  Looked right.

 

Length on both springs, end-to-end:

 

M2_zps3jbvrnea.jpg

 

Didn't feel like drilling the lower to use a 6-32 set screw, so I just ran the 4-40 tap in the stock hole - no drilling required to run a 4-40, if you decide that. 

 

M3_zps4nyofxol.jpg

 

4-40 set screw going in:

 

M4_zpsxqo2cf4e.jpg

 

Done:

 

M5_zpsg21lxpb4.jpg

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  Nice job  <thumbsup>

 

   If some are shy about tapping their new Receiver , Brownells sells Compression spring stock & it would be an easy thing to get some & just make a longer spring , sounds like 98's total spring size would be a fit . Spring stock come in 1' sections , so you can experiment  with what size gives the proper tension on the Detent & its doesn't have to be much .

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   you can experiment  with what size gives the proper tension on the Detent & its doesn't have to be much .

 

That's it, right there.  Doesn't require alot of tension to keep the takedown pin in place.

 

This goes for AR15s, too, when doing the set-screw mod - if you cut long, you're better off.  Chop, install, find out that your takedown pin is hard as hell to get moving - NO PROBLEM.  Take it apart, and cut off another coil or two from the spring, and reinstall and retry.  Get it to where you want it - there is no magic number or length.  It really doesn't take alot of pressure to keep that pin in place. 

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