Gents;

Hoping someone can advise me on a .300 BLK SBR build. I have a 10.3" Daniel barrel with an AAC BrakeOut and an AAC 762 SDN-6 can that I plan to mate to an Adams Arm XLP piston kit (which requires a standard barrel nut). Also, while I would like the can to fit under the forearm just a bit to give it that "MP5 SD" look, I would also like the option to run the gun unsuppressed as well. Given these constraints, choosing the correct forearm is a bit difficult. I think that I need to go with a Samson Evolution forearm since it works with a standard barrell nut and has an ID of 1.56" (which is wide enough for the can to fit underneath it), but I do not know what length to get. Is an 11" forearm too long for this build? Would I even be able to get the can off without removing the forearm? What about a 10"? Would the can actually fit (or even touch) a forearm this short?

Any advice, thoughts or suggestions on this would be greatly appreciated? Money is particularly an issue for this build, but what I don't want to have to do is have custom machine work done on any of the parts, due to the general "pain in the ass" factor of arranging such work. I would really prefer the correct combination of "off the shelf" parts to make this build work. Thanks so much for your help with this!!

Get a Seekins or Spike's BAR rail (they are the same). These rails are made for suppressors to fit inside. Go with a 12" rail (there are less gaps near the very end of the rail, so I think an 11" rail will end up being more difficult to remove the can). See here:
https://www.youtube.com/watch?v=anHm2TBSY_0&feature=youtube_gdata_player

Whoops I see that you want to use a standard barrel nut, and the Seekins/Spikes rails do not. If money is a concern, why spend like $150 on a piston conversion kit? Just go with a proprietary rail system and get an adjustable gas block and gas buster handle. Although I must say that on my 10.5" 300 BLK, I just run a heavier buffer and don't have a problem with gas in my face or reliability shooting subs or supers, suppressed or unsuppressed.

The Samson is a good rail for what you want.  You might want to get the keymod option though so you have more room to get the suppressor off.

10" hand guard will do what you want.  I have a 10" BAR rail on my 10.2" Noveske barrel, about 1/4 or so of the flash hider is under the rail. so it can be shot with or without the can. The end of the barrel is pretty much flush with the end of the rail, so all of the threads are under the rail.

dvp18;

Thanks so much for posting the pics - that's exactly what I was hoping to see!! :-).

So you have no problem removing the can without having to remove the handguard as well?

d16man;

I hate to ask an ignorant question but I dont understand why the Keymod foream would give me more room to get the can off. Is the Samson Keymod forearm designe differently than the normal Samson forearm or does it have a wideer ID? Please elaborate. Thanks so much!

No, but I am using a Saker that just screws on and off one handed, it might be trickier with a can that has a latch or lock ring at the base that has to be engaged.