PSA Upper on DPMS LR308 Lower

[Wade Brown]

I purchased my DPMS LR308 almost 8 years ago, I had been thinking about buying one and then Obama got elected and I was worried about another Assault Weapons Ban so I ordered immediately after he was elected.  I was never happy with how it shot it would shoot about 1.25 MOA consistently with reloads, I have reloaded for almost 40 years and spend a lot of time shooting F-class at 1,000 yards so my reloading skills are not too bad.  I shot maybe 1,000 rounds through the LR308 trying to find a load it was happy with, there were quite a few loads that shot 1.25 MOA but that did not make me happy.  I have not shot the LR308 in maybe 4 years.  I tried multiple triggers that have worked well for me in the past on other ARs so triggers probably were not the problem, I assumed barrel.

I have shot a lot of 6.5's and love how those bullets do at 1,000 yards.  I have a number of 6.5 mm blanks at the shop and a lathe, a dangerous combination, or at least an expensive one.  So I decided to build a 260 Rem upper to put on my LR308 Lower, I looked around and I saw that some people had bought PSA PA10 uppers and used these on their DPMS lowers, the price was right so I ordered a blem PA10 upper, a BCG and some other parts since I was making an order.

I got the blemmed upper yesterday and I could not find a blem and the machined looked fine, the same can be said for the BCG.  This AM I pulled the LR308 out of the safe, took the upper off, put the PA10 upper with charging hamdle and BCG on it, on the LR308 lower, the takedown pin went right in and all looked good.  So I tried to opon the bolt, and it came back about 1.5 inches back and bound up in the buffer tube and would go no further.  I assumed an alignment problem, I put the DPMS bolt in the PA10 upper and it bound up the same way. 

I took out the takedown pin to see if I could get the bolt to operate if the upper floated a bit, the bolt operated as it should with a little slop in the assembly.  The slop allowed the BCG and buffer tube to align themselves.  Floating the upper in this way allowed operation with both BCG's.

So I called PSA customer service and repeatedly heard "We only guarantee compatibility with our lowers." or something along those lines repeatedly.  I asked him if he had heard of many people using PA10 uppers on DPMS lowers and I just got the above statement about compatibility.  I was trying to see if this was a rare occurrence thinking maybe the PA10 upper is out of spec, the compatibility statement did not give me any information.  So I decided to ask the hoards of owners of 308 AR's on the web for their collective wisdom.

Does the PA10 upper usually work on the DPMS lowers?

It seems strange that PSA would engineer an upper that is about 0.003" away from compatibility with one of the common lowers on the market, I realize their desire is to sell both uppers and lowers but 0.003" movement might provide a larger overall market for them.

TIA for you collective wisdom,

wade