Sounds like the jig was made faulty... You've already got one receiver that doesn't work. I'd be getting the .308 jig BA makes, for sure...

Found a schematic on AR15.com. It shows it centered... Scroll a little over 1/2 way down the page...

https://www.ar15.com/archive/topic.html?b=3&f=118&t=665458

Last edited by scorpiusb (3/19/2016 1:37 pm)

When it comes to the 308 platform, its rarely the same dimension from manufacturer to manufacturer.  I'm guessing DPMS dimensions have adjusted over the many years that they made the LR-308.  The distance of the 3 hole pattern moving together front or back will not affect the function of the firearm.  (as long as its a little difference).

But that little difference will affect the position of the safety because the safety detent was already put in by the manufacturer of the lower.  So you ALWAYS use the dimensions the manufacture gave you.

The most important thing is that the 3 holes (hammer, trigger, safety) stay in relation to each other.


Here is a pic I located on a message board a year ago.

Also, Thank You for bringing these type of questions up in the message board.  308 is a f*** mess when it comes to matching parts.  And these types of discussions help others understand building their firearm.

I dont have pics.  But the detent and safety are the same location 6.138.  Since that was the original question, I should have addressed that..  haha  sorry.

Since I last posted, I was able to mock up my BA .308 lower in my existing drilling jig. I lightly scribed where the hole for the safety detent would be drilled and it seems that it will align correctly with the detent hole. The previous lower (not from BA) is some kind of weird 1/2 &1/2  design where some features were direct from the AR15 print  and some were from the .308 prints. Examples are the takedown detent hole is drilled from the buffer end instead of up from the bottom and requires a special longer detent spring. The bolt release uses the same roll pin as the AR15 instead of the threaded pin which makes the 308 bolt release lever sloppy since the hole in it is for the threaded pin and is slightly larger than the pin. The outside was made to look more like a large AR15 lower. I write this to reinforce Mikes comment above stating that 308 is a f*** mess when it comes to matching parts. 
That said, my existing jig seems to index correctly with the BA lower and will most likely work, but I am still leaning towards the BA jig because it requires less set up and removes more metal before the milling step which will be far easier on the mills and the drill press - and me. 
Mike,
Can you tell us where you are at with the .308 top plates being ready to sell? 
Are you planning on producing uppers by any chance. Or could you recommend any that would be as high quality with the same attention to detail that you put into your lowers?