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80% DPMS Lower - .308 Flat Top AR Style Build

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Recoil Magazine has an article on the 80% AR10/.308 AR lower build.  I’m looking into doing one with a DPMS style lower.


I’ve done some searching on the forum and would like to ask a question for the knowledgeable (been there - done that)  people on this forum.  I want to buy once and not build a pile of aluminum I can’t use.


My understanding is there are “Low Profile” and High Profile” uppers (Flat Top) for the DPMS style builds.  I’m trying to identify my options for an Upper.  Being new to building an AR10 (done AK47 & M4) and want to get my arms around the options and what is going to be my best options.


What are the best choices for a Flat Top upper w/forward assist and complete Bolt Assembly and why?


I am looking at making a medium to long range rifle with optics.


Help Please…


Thank you in advance for your assistance!



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  An 80% lower build , I think I would be more concerned with the proper machining process of finishing off the lower receiver , because its only 80 % done , of course . Something I haven't even wanted to try because of tooling & Machining you need to do it yourself .


 The upper receiver rail height is not really a concern too much , except if you want to match the hand guard & upper receiver rail heights . I only use matched sets of receivers any more, on builds , because of (on 308 AR's ) there are no MilSpec standards for them from one manufacturer to another like the AR 15 line of receivers . 


 The possibility of Tolerance stacking between the different manufacturers of receivers is always a possibility . I know the popularity of 80 % lowers is growing & very attractive to do for many reasons & if you are going to do a DPMS type , find a DPMS upper type to use (DPMS ,Fulton Armory, TM & several  others seem to work ok)  . I have both a DPMS older rail height upper receiver on one of mine & a Tactical Machining newer rail height upper on my other 308 AR . Both are on DPMS manufactured lower receivers & have no problems .


  I did have another unmatched set of receivers( both Billet ) on the 16" bbl. build & had various problems( long story & its on this forum , some where ) , the main one being , it would FTF with the Magpul LR PMags . I switched those out to the present configuration of DPMS lower & TM upper (with out FA ) & she runs like a top with any Mag..


Good luck & have fun , nothing like a new build in a different caliber & of course in our preferred caliber , 308.

Edited by survivalshop
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I’m sorry, I may have missed (or did not make clear) my goal with this posting.


The lower in question is of a DPMS make/style.  My goal is to get an upper that will make the rail on the upper match the height of the rail on a good quality, full floating hand guard.  My understanding of the DPMS style uppers is the rail height can differ by about a ¼”.


I’m looking for my good/high quality DPMS upper options which will match the requirements listed above.


I apologize for my struggling new guy questions.  I thank you for your time and input!


Best regards,



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  Two ways , 1 ,buy the upper receiver you want & match its rail height to the FF hand guard or 2 ,buy the Free float ( FF ) hand guard you want & match the proper real height upper receiver. The manufactures data will tell you what upper receiver rail height there hand guards will fit .


  I can tell you ,because I have one of each, that the DPMS & Tactical Machining upper receiver rail heights are the same , the DPMS now a days are the lower rail height from what it was a few years ago . I have a Fulton Armory upper receiver & a SI Defense ( Billet ) upper receivers that are the older higher rail height . 

  If you can't find the rail height match through the manufacturers data , you can call , email or just post it here , I'm willing to bet , some one has a build here with one & can tell you .

Edited by survivalshop
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