Fairly new to the forum, but long time lurker. I thought I would share my experience with the MDR for people who are looking at them now. I'm going to try to be detailed but keep this as succinct as possible.
I pre ordered the MDR in 308 in 2016 as a deployment gift to myself. I got the rifle at the end of May in 2018, a little over 2 years after I ordered it. Throughout the time I've had the rifle I experienced basically problem you could have with the rifle, and every fix. I currently have a little over 1700 rounds through the rifle.
When I first got the rifle I had a a failure to extract with a ripped rim approx every 50 rounds, sometimes more with different ammunition. I primarily shot PMC 147 and the PPU match that I bought specifically to break in the rifle. I had a failure to eject about every 20 rounds due to short stroking. Removing the chute remedied those failures, but not the ripped rims. I received the first 6 position gas block and that solved a lot of my issues. I had a ripped rim about every 150 rounds, and a failure to eject much less frequently for about 500 rounds, then I got the 2019 gas block and the extractor upgrade. The barrel went back to the factory for that. I had zero ripped rims after that upgrade, and no other failures for about 500 rounds. Throughout owning the rifle I had a constant issue of the rear takedown pin working its way out just a little bit while firing. It would only be about 1/8" out of the receiver but that was enough to notice and the pin would not support where it needed to. When I received the barrel back they sent a new retaining pin for the takedown pin and a new takedown pin. The issue with the retaining pin continued to a lesser extent.
After about another 250 rounds I noticed the part of the rail the takedown pin was held in on the right side had a small crack forming along the bottom edge. I believe the takedown pin walking out was associated with the stout recoil, and the damage was caused by firing while the retaining pin had walked out. I let Desert Tech know and they paid shipping for the rifle to go back to the factory.
When I received the rifle back I took it out to test it and it was completely different experience. The recoil was noticeably softer, the rifle ejected through the chute with more authority, and the rims lacked any sign of puling. This indicated to me that the timing in the gas system had been improved. Unfortunately America's oldest war required more of my time so I will have to wait on more testing till later this year.
Accuracy throughout has been good, as I expected for what the rifle was designed for. Using a Trijicon 1-8 my 10 round groups averaged about 1.5 MOA, and 20 rounds would be 2 MOA to a hair over. That accuracy held at distance, and 750m hits on 2/3 sized silhouettes were consistent. With the profile of the barrel I saw the groups open up after 6 or 7 rounds and peak at about 20 rounds. I regularly shot strings of 40 to 75 rounds. I didn't notice and appreciable POI shift , just groups opening up. Shooting 1 MOA with short strings of 3 to 5 isn't too difficult, but since I primarily shoot long strings at steel from 450m to 950m I don't see a lot of merit in making that claim. With a TA11 the rifle is significantly lighter, but I'm only able to get about 2 MOA, but I'm sure there are people who could do better with that optic.
I have been pleased with the rifle even through all of the updates and changes. I'm sure DT will continue to improve the rifle and I have ordered an MDRX in 6.5 that I intend to wear out. I think if the M16 came out in todays age with the amount of scrutiny manufacturers get I can't imagine it would go over well. People are quick to scrutinize and expect perfection, yet most are not designing rifles or investing in manufacturing. There are certainly things that the company should have and can do better, but it is very apparent that they are willing to make it right. I have not had any issues getting ahold of their warranty department, even from Afghanistan. I've talked to Nick directly, as well as a lot of their staff, and in my opinion they are doing a good job of standing behind their product. I'll continue to shoot it, and if it has issues I'll send it in under warranty. Hopefully this is helpful for people looking for info. I have had my fair share of frustration, but I choose to try to help remedy the issues. As long as the company is backing their product I'll support them.