Starting off, I have no interest in .308 and especially not in an AR. However, my brother decided to get into just that and he picked up most all the parts for one. My knowledge on .308 ARs is basically non existent because their lack of standardization turned me off to them. But, if it makes any difference the lower that he plans to put the UBR Gen 2 stock on is from Aero precision (he's sticking with their parts for the majority of the rifle).
Anyways, the waters are muddy trying to figure out which spring and which buffer we will need for this set up? And I'm also not sure if the included spacer that comes with the UBR Gen 2 would be needed or not?
I'm also uncertain on pistol grip compatibility with the Aero .308 lower, but it seems like Magpul has 2 different versions of the MIAD grip with one being specific to .308 lowers. So I'm assuming that they are not interchangeable?
Thanks for any guidance.