DANIEL DEFENSE - MK12 SPR 18" 5.56mm NATO 1-7 12" DDM4 Rail Upper

I feel like I have to write a review because of this other review giving only four stars. First off, if he wanted to use the DDM4 rail or Mk12 upper he should’ve checked compatibility before purchasing. Could have even asked DD in an email to their CS. It’s not really fair to give a subpar review because he made a mistake in assuming that the DDM4 rail was compatible. Do your research before you buy. This is without a doubt in my mind a 5 star product, it is a civilian use model and should fit standard AR-15 lowers. and any small pin receiver. I don’t recommend grind the head of the bolt down. Just get a different lower. They are cheap and readily available. Or just buy a complete Mk12. If you want a Mk12 to use with a large hole receiver go with a PRI handguard model. I have both and both are fantastic and make me wish I had more ammo because I love shooting each of them. This is one of those guns that just makes you want to give your kids up for adoption so you can have more free time and money ti spend at the range. Its that good. I’d give six stars or more if that was an option. I recommend swapping out the muzzle device for Aa AE brake and collar system and getting your hands on am OCM5 suppressor if you have the means. It makes it all that much more and then some in the smiles and giggles department. Cannot recommend enough. Pic is of my BCM/PRI Mk12 and my Mk12 clone build with the DDM4 rail,

This is a very nice upper but you need to be careful if you plan to install it on an old lower receiver with the large hole. I am installing it on a Colt SP1 lower which has the large hole so I need to use an offset pin. However, the DDM4 rail has 4 installation bolts and the head of the bolt near the front pivot pin prevents the offset pin head from going all the way in. I called Daniel Defense and they said that they do not support using it on a large hole lower. I asked if I could take out the interfering rail bolt and installed it from the other side. He thinks it may be doable and he suggested to just use three bolts (it should be tight enough). However, when you rotate the bolt, as it comes out, after it rotates out about 1/3 inch, it hits a part of the upper receiver that juts out a little. This caused me to scratch the receiver a little bit as I did not expect that anything will be in the way of the bolt coming out (I'm not sure how they installed it originally). I tighten the rail bolt back and now my only option is probably to use a grinder to grind a little bit off the head of the offset bolt to just clear the blocking rail bolt. Will need to get a grinder first. I was hoping that it was plug and play but this turned out to be more work than I expected. The finish also seems to be easy to scratch.