The AR-15 pattern of rifle is almost stupid simple to put together into a system that functions reliably, and generally you can find at least some ammunition that will be both reliable and accurate.
Not so with the DPMS Gen 1 LR-308 platform. Putting mine together was nowhere near as simple as purchasing the correct parts and assembling, validating headspace and enjoying. Nope, not at all.
My LR-308 had…problems. And believe it or not, none of the problems were associated with the 80% lower I finished with a drill press.
My two symptoms from my initial build were inconsistent cycling, and cratered primers on known good loads and even low power handloads. Spending over 200 dollars on a JP Enterprises high pressure bolt, which is like a normal bolt that has had the firing pin bushed, fixed the cratered and pierced primer issue, and increased the reliability of the cycling. There was obviously a lot of variability in cycling resistance, even when I hand cycled the action. Since the cycling inconsistencies remained, so I cut three coils off the buffer spring, and lubed the snot out of it, which also helped. So 20 dollar “flat spring” to the rescue, and now cycling the action is much, much more consistent. The normal coil spring, which I’ve used for decades in AR-15 pattern rifles without issue, somehow binds in the “ridges” found inside the LR-308 buffer tube, which brings up the question why in the heck does the internal surface of the buffer tube have ridges that the spring can bind up on?
So what does this mean to you? Well the large frame AR isn’t as user friendly as the AR-15 platform. Especially since there are multiple competing form factors, DPMS Gen 1 and 2, Palmetto State Armory’s proprietary builds (which are just fine if you are buying a whole rifle), and Armalite’s AR-10 and AR-10B. Of all the formats, DPMS Gen 1 is the most common, but it is also pretty dang heavy compared to some of the other formats (Gen 2 really cut a lot of fat off the frame).
Another issue is that large frame ARs don’t shoot like bolt rifles, and they don’t exactly shoot like AR-15s either. Some say you need to free recoil them for best accuracy, other say you need a solid death grip lock like you would with a Garand or M1A….honestly even with over 400 rounds through mine I can’t tell you which is the best technique. One day it shot five shots into a tight quarter size group, the next it opened up to a baseball, and I couldn’t tell you why for the life of me. Is it the AR-Stoner brand barrel? Or the Vortex Venom scope? Not sure, but I may send that scope back to Vortex for a thorough checkup (several hundred rounds of 308 might have knocked something loose).
So….after all the expense of putting my own LR-308 together, the total cost ended up greater than had I just purchased a Palmettos PA-10, or a similarly priced full rifle from a reputable dealer… I did get the experience and knowledge gained from putting parts together, and then purchasing different parts to fix problems, and turning over 400 pieces of precious ammunition into marks on paper (sometimes, other times it was hard to get on paper), using three different powders (IMR4064, IMR4166, and Ramshot TAC), two different bullets (173gr FMJBT and 175gr SMK), in good Lake City brass with a milspec primer.
So now to test out that 6.5 Creedmoor upper I put together….