I thought the suppressor section was the most appropriate forum for this. Just got a DDM4V1 on sale.  16" full handguard but has carbine length gas system (couldn't resist the $699 for the upper),  I have a 5.56 YHM Phantom QD that I use on my 11.5" POF with H2 buffer without any issues.  For the DD, I installed an extra power Sprinco (red) buffer spring and a Spikes ST-T2 to compensate for the short GS.  It runs great both unsuppressed and suppressed, but I get the usual gas face with the can.  The question is, should I get a Noveske switchblock clamp on ($185) and it fits the 12.0 FSB handguard or save the money and just RTV the CH or get a gas buster?  Any thoughts on the clamp on switchblock, as Noveske cautions its use for defense (loosening concerns)?

I wrote this for some one who sent me an IM on the switchblock, it may help you to:

I have two rifles with them; a 14.5 Carbine and a 16" Middy. I run an AAC M42K on both rifles.

Switch block has 3 setting (as you probably know) �Open� �Off� and �Suppressed�. The block is rotated my pushing a small detent and then rotating to the next setting. This is easy to do but a little tough with gloves on. Note here: Don�t try it when the guns hot, ouch! ask me how I found that out! Finnish and machine work on the block is first rate. The Factory installed blocks are mounted to the barrels via one taper pin; retro fit blocks are done with two set screws. I have both types, my 16" is the set screw type. I witness marked the screw set one and never had movment.

Use Non-suppressed: I've run apx 3500 rounds with my Noveske 14.5 conditions ranging from Rifle Class, outdoor shooting, outdoor drills in the rain and plinking; never a failer of any sort. Vast majority of that being XM193 (Both Privi and Federal), followed by Privi 75 grn Match ammo, 77 grn Black Hills Blue box and a small amount of 75 grn 5.56 Tap. Unsuppressed the rifle runs just like any other gas system. My 16" BCM Middy has abought 2k, a few teathing problems early traced back to bad primers.

Use Gas turned Off: I've done this a few times mostly farting around at the range. You get some funny looks from other guys who are desperate to help you trouble shoot a single shot AR. I did this mostly to see if there was a POI change with the gas off. I could not detect one. With the gas off you have a single shot rifle, I did not find any problems charging with the charging handle but I could see were a dirty chamber and you may get stuck cases.


Suppressed: I'm in WA, and while it's legal to own a suppressor it is however illegal to discharge a suppressed weapon in the state (retarded? Yes). That said I have gone to �Oregon� to shoot. I only have apx 500 rounds through both guns suppressed; fairly equally balanced between the two. I've shot both with the gas �open� and in �S� mode, slow and rapid fire.

For the record I use Gunfighter Charging handles with the RTV trick. This is silly easy to do and I recomend you do it.

Gas �Open�: There is a crap ton of blow back and the bolt flies to the rear especially with the carbine. The Middy was slightly less obvious that the system was getting to much gas. Even with the TRV trick the amount of gas pouring out the back was noticeable. Both guns ran fine with suppresser and gas system �open�.

Gas 'S": When running the rifles on �S� setting things are noticeable tamer. The bolt reacts much more normally. There is still a LOT of gas in the gun, but with the RTV trick and the switch block on �S� the amount coming out of the rear of the gun was noticeably less and rapid follow up shots much easier and clearer than with a face full of gas with the system �Open�. I've not had one failer with the system on �S� with a Can. Noveske got the gas tuned will; each barrel length & gas system have their own switch Block; ie a Carbine switch block cannot be put on a middy gas system by changing the tube, it won't run right.

That is where I will make a note: There is ALWAYS going to be X amount of gas from the gun. The Can, switch block ect only change were the gas is going. The can will trap a lot of the blast, sound and all the flash but there is still a lot of gas coming out of the end of the can and the gas the gun needs to operate. The thing the RTV trick and the switch block does is keep 80% of that gas coming out of the front of the gun, and ejection port; not under your nose and face like a normal rifle would.

The Bad: Buy the Wrench Noveske sells. When you shoot that switch will be HOT, you will need the wrench if you want to move the setting when the gun is hot. After shooting you may also have a problem with un-burnt powder making the gas block sticky and hard to move by hand; the wrench makes this easier to do. That AND having to make sure you set the gun up right for use are the two big things I�ve noticed. I left the gun on �S� after removing my can and went to a shoot and had a failer drill right off, and right after and then I changed it to �Open� opssss�. Now I train myself to leave the gun default in �open�.

I'm a gear snob when it comes to weapons lights and rifles; Surefire for lights and Noveske, Colt and BCM for AR15's. I will be buying another Switch Block gun and I can't imagine unless I'm making a Kiss gun not having it Switch Blocked with a suppressor mount.

Hope that helps!

Thanks for the detailed info, sounds like the switchblock would be helpful and I'm encouraged that you had no movement of the clamp on block.  I plan to RTV my gunfighter CH as well.  My POF (POS due to the heavy rail) has an adjuster block for normal and suppressed, so I'm already used to defaulting back to normal.  I will post the final outcomes.  Many thanks. -SS

It would be very helpful.  16" carbines are especially prone to pressure issues when suppressed because of the gas port location / long dwell time.