New to the forum 1st lr-308 build.

[natedavis49686]

Hello,

This is my first post/introduction. I am an enthusiast/hunter/shooter/guide. Ever since my first AR build, I've been hooked! I'm finally starting my first large-frame build, and have a quick question...

For a wedding gift, my groomsmen pitched in to get me a lr.308 "custom lower". I purchased a DPMS upper to get this rifle started, but there is a serious gap back by the extension. I know there is always a little gap, but I am concerned with this amount (attached)

Is this a lower receiver issue? Or is the DPMS upper out of spec?

Thanks a lot for any help or advice on how to proceed!

-Nate

[EasyEJL]

does it jiggle much?

[Matt.Cross]

There are a whole lot of possibilities here, I'd try to locate another upper and check it too. If it also has a large gap, the dimensions on your lower could be wrong, possibly something as simple as a mislocated forward retaining pin hole. If no gap with a different DPMS type upper, most likely the upper is out of spec.

[AdamO]

That's the problem with the whole .308 AR world.  There is no mil spec like there is with the AR15 so there are no guarantees that everything will be plug and pray.

 

The best rule of thumb is to source your upper and lower from the same place but in your case it was a gift and it's a custom piece so what do you do?  Maybe the place that made your lower has a matched upper that they sell with it?

 

That gap might be a concern and it might not.  have you run any ammo through it yet?  Does it cycle properly?

 

For reference, here is a pic of how my Aero Precision upper and lower fit together.  Bought them together as a set.  It's a pretty tight fit.

[natedavis49686]

Thank you for the responses! There is a very small amount of "wiggle" at the front retaining pin. None of my M4 clones have this "wiggle" or any slop (they are all matched upper/lowers though).

I'll try to find another upper and see if that may be the issue.

Thanks again guys,

-Nate

[planeflyer21]

Welcome from AZ nate!

[unforgiven]

Welcome from Indiana brother Nate.

[Gibbs]

Welcome from Michigan! 

[blue109]

are you sure it's a factory DPMS upper? I could be wrong, but judging by the thickness of the metal over the charging handle slot it looks like it's the "old" DPMS height receiver. DPMS hasn't made those in a few years, but several other companies still use that height standard. it would be odd to buy a new DPMS upper and get the old style.

again...this is just a guess from looking at that pic. my eyeball might not be calibrated.

[blue109]

I pulled miss piggy out to compare, and on second glance your gun does look about right for a newer DPMS height.

I just like any excuse to pull miss piggy out.

[Rsquared]

Welcome from MD Nate.