Dd mk18 suppressed or sell it and get a piston setup?

Fenix Mike

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Minuteman
Aug 19, 2012
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Tulsa, OK
We'll after a nice 11 month wait, suppressors are in my hands! I've had a dd mk18 upper on my registered lower for a while (all properly setup for sbr) and it's functioned flawlessly, however my other guns are either piston or adjustable di for the suppressor so it got me thinking about selling the mk18 upper for something with adjustable gas. Am I stupid for thinking about selling the upper or would I be better off with say a sig 516 10 inch that I can gas down for the suppressor?
 
Why dont you just spend $60-$120 and buy an adjustable gas block. There are low profile ones that fit under most rails. Plus if you decide that you still dont want it then just sell it. That way you are only out $120 at the most instead of the cost of a new upper.
 
Why dont you just spend $60-$120 and buy an adjustable gas block. There are low profile ones that fit under most rails. Plus if you decide that you still dont want it then just sell it. That way you are only out $120 at the most instead of the cost of a new upper.

None will work with the mk18 setup, the suppressor is thousandths of an inch from the end of the rail. I can also sell the mk18 upper for just about what the sig upper costs new, so it would be a wash.
 

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Do you have functional problems or is it just because you want an adjustable gas block? Which model suppressor did you get?

Sdn6, haven't had a chance to try it on my 223 gun yet, only on the 308 stuff. Probably going to try to get some range time in a week or two with it, but this area sucks for shooting and I have a rough schedule. Figured I'd look into it before I go play since the mk18 upper only has a couple hundred rounds through it and gunbroker has a few 10 inch uppers on it. It's flawless without the suppressor on xm193, but I like being able to turn the gas down and not launch brass 20 feet away if it has too much pressure. The sig 716 and armalite were flawless suppressed, but both had a suppressed setting... Just debating if I want/need that on all my guns, or if I should just go shoot the hell out of it and decide later.
 
Personally I'd sell it and get a 300 BLK upper but that's just me. That said I'm a huge piston fan as well as I own a LWRC myself.

It's on my list, but I sold my reloading setup when I moved here because this state sucks so bad. Going back to az next month thankfully and will probably get another Dillon, then look into 300 AAC again. It's too expensive to shoot without that, but an 8.5 inch upper for that round is likely in my future.
 
I have a DD 5.56 MK18 block II and Colt MK18 mod0 with KAC NT4 suppressor and both uppers run 100% with and without the can. I would give the dd a shot with your can and see how it runs before you move it.
 
Do guys really have that much of an issue running suppresors on standard DI rifles? I've ran them on 14's to 20's and never had an issue or need an adjustable gas block. Is it hand loads?

My 18" noveske that I had in Astan with a Gemtech never even had a single jam in everything from getting dope, engagments, or near ambushes where I was dumping mags.

So school me Semi-auto gurus, what am I missing here?
 
Do guys really have that much of an issue running suppresors on standard DI rifles? I've ran them on 14's to 20's and never had an issue or need an adjustable gas block. Is it hand loads?

My 18" noveske that I had in Astan with a Gemtech never even had a single jam in everything from getting dope, engagments, or near ambushes where I was dumping mags.

So school me Semi-auto gurus, what am I missing here?
Its more of an issue with pressures and not being able to regulate the gas system, can cause some hard ejections, launching brass across the range etc. My SASS has the adjustable regulator to limit the gas when shooting suppressed, and the Sig has 4 settings (over, normal, under and off) which I really like... When I turned the SASS down, I had a nice pile of brass at 2:00 about 4-5 feet from the gun and I swear I could have put a trash can there and caught every one. Sig was similar when turned down, I just havent shot this gun yet and since its a factory SBR, its built for the already short barrel, just didnt know how they did suppressed. Im sure almost any DI gun will shoot fine with a can on it, just not optimized like a lot of the newer guns that come with adjustments.
 
I've never had a single issue running a can on a DI SBR upper. I've had 4 LMT 10.3" uppers, 5 DD 11.5 and 12.5 uppers, BCM and a couple others and none of them ever hiccuped when running suppressed and that was typically shooting shit ammo.
 
I've never had a single issue running a can on a DI SBR upper. I've had 4 LMT 10.3" uppers, 5 DD 11.5 and 12.5 uppers, BCM and a couple others and none of them ever hiccuped when running suppressed and that was typically shooting shit ammo.

I figured as much, just wanted to clarify before I go run this thing... now was the time to sell it before it gets covered in sweet carbon and crap from running suppressed :)
 
After reading this thread I hit the range with the dd MK18 and blasted about 300rds of fed xm193 and PMC bronze all suppressed. Mine at all of it and its just as reliable as my trusty Colt Mod0. The MK18 platform was designed to drop on top an M4 lower and rock n roll. No adjustments to screw with or fine tuning gas block BS. It would be a mistake to ditch the proven DI system dd upper and jump into non standardized piston game.
 
After reading this thread I hit the range with the dd MK18 and blasted about 300rds of fed xm193 and PMC bronze all suppressed. Mine at all of it and its just as reliable as my trusty Colt Mod0. The MK18 platform was designed to drop on top an M4 lower and rock n roll. No adjustments to screw with or fine tuning gas block BS. It would be a mistake to ditch the proven DI system dd upper and jump into non standardized piston game.
Sounds like im keeping the Mk18... I love that thing anyway! Just wish DD sold stripped lowers so I could register another one and have a full DD gun.
 
Sounds like im keeping the Mk18... I love that thing anyway! Just wish DD sold stripped lowers so I could register another one and have a full DD gun.

I was going to say if you decide to ditch the MK18 let me know I would give it a good home. I have been trolling the "For Sale" forum hoping one would show up. Guess I will just buy one of GB or from my dealer when I get home.
 
I was going to say if you decide to ditch the MK18 let me know I would give it a good home. I have been trolling the "For Sale" forum hoping one would show up. Guess I will just buy one of GB or from my dealer when I get home.
everything is for sale for the right price... Always welcome to PM me with an offer :)
 
An adjustable gas block will allow you to run your upper suppressed at the proper cyclic rate for optimum reliability, minimizing recoil at the same time. And it won't dump as much gas back into your gun!

IMG_2634.JPG


720 RPM suppressed with M855. A tad faster with my load of choice, ASYM 70 TSX. Not that I ever shoot suppressed other than to check the cyclic rate! It's simply the best clue as to how much gas your suppressed rig is getting.
 
Do guys really have that much of an issue running suppresors on standard DI rifles? I've ran them on 14's to 20's and never had an issue or need an adjustable gas block. Is it hand loads?

My 18" noveske that I had in Astan with a Gemtech never even had a single jam in everything from getting dope, engagments, or near ambushes where I was dumping mags.

So school me Semi-auto gurus, what am I missing here?

Its whiney bitches who read to much shit from other whiney bitches who think they know what they are talking about.



As far as the gas goes, they need nut the fuck up. Pick another hobby if you can't deal with a little gas in the face.

Almost as funny as the retards saying to replace a 5.56 upper with a 300 WHISPER upper.

There is no need for an adjustable gas block on a quality 10.5 gun can or no can.
 
Cobracutter I agree 100%. Leave the gas alone and run it as is. All the adjustable gas tinker toy crap drives me nuts. Leave the DD all factory and just buy more ammo instead of wasting money on uneeded parts. Again, I have two MK18s. A factory Colt with smaller gas port and the DD with larger port. The DD recoil is a tad more noticeable but the barrel is accurate as all hell! Marginal differences that do not effect overall performance are just fine by me.
 
If what youre implying with high pressures and gas blow back etc is that you're looking for a better recoil impulse and an overall softer shooting 10.3-10.5" you should look into selling your DD and picking up a Noveske switchblock. Mine runs wonderfully on the suppressed setting with anything I've ever thrown in it. Add in a PRI Gasbuster and you've got no issue with gas in the face. I recently built a 7.5 piston upper with an Adams Arms XLP kit just because I wanted to get as short as I possibly can, but nothing I've shot - BCM, LMT, DD, POF - have shot as smooth as the Noveske. Food for thought if nothing else...
 
I strongly disagree with the notion that a suppressed SBR will not benefit from an adjustable gas block.

I'm very fortunate to have been able to purchase a Colt M16A1 full auto lower a LONG time ago. But, I typically don't shoot full auto these days other than to check the cyclic rate of a given weapon with an electronic timer.

Based on my own experience, 715 - 775 rounds per minute rate of fire works well for most AR' format weapons, regardless of barrel length. Ammo type and recoil system format cause far more variation than I'd ever imagined, unsuppressed. Change the cyclic rate 100 RPM by going one step lighter buffer?!? As wild as that sounds, you can't imagine how surprised I was to see what happened suppressed.

Add a suppressor, and what do you get? Well, it depends somewhat on the brand and the model of the suppressor. And ammo! Surefire suppressors have lower back pressure than any suppressor of which I am aware. That's one of many reasons I only use them on gas guns. But, strap one on and still watch the cyclic rate jump up 35%!!! It is much more with some brands. I've seen some well liked brands choke an SBR AR' to death.

When an AR' runs faster like this, it is only the rearward motion of the bolt carrier group that is faster. The recoil spring pushing everything forward operates the same in semi or full auto. Just hope that magazine spring gets the next round in position in time!

So, what's the downside of this faster rearward BCG business? The biggest problem, I think, is the brass does not have time to relax fully prior to extraction, for starters. Plus, there's excess wear and tear on all associated components. And more felt recoil. Harder to keep your sights on the target shot to shot. Keep in mind this happens in semi, too, shooting suppressed, not just full auto!

My 10.5" shown above runs at 720 RPM with M855 suppressed, but slightly faster with my ammo of choice, ASYM 70 grain TSX. The apparent recoil is next to nothing, noticeably less than unsuppressed. The weight of the suppressor out front keeps the dot on the target. Less gas is getting dumped where the gun eats. And it is uncannily accurate! If I told you what it would do, you would not believe me, and I wouldn't blame you for that.
 
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Some other info I picked up in this testing:

Magpul magazines run at a 10-15 round per second higher cyclic rate than even the very best aluminum magazines I've got (Teflon DSG's with Magpul followers).

The variations in the splits, shot to shot, with Pmags never exceed 0.01 second, from round 1 to round 30. Most splits are identical.

GI mags produce some wild splits in a full auto mag dump, as much as 0.003 second slower at the top of the magazine as at the bottom. And choppy!!! You can hear the lack of cadence.

This to me means the Pmag feed ramps are smoother. Feeding is more consistent shot to shot. My theory is this means improved reliability and potentially even better accuracy.
 
If what youre implying with high pressures and gas blow back etc is that you're looking for a better recoil impulse and an overall softer shooting 10.3-10.5" you should look into selling your DD and picking up a Noveske switchblock. Mine runs wonderfully on the suppressed setting with anything I've ever thrown in it. Add in a PRI Gasbuster and you've got no issue with gas in the face. I recently built a 7.5 piston upper with an Adams Arms XLP kit just because I wanted to get as short as I possibly can, but nothing I've shot - BCM, LMT, DD, POF - have shot as smooth as the Noveske. Food for thought if nothing else...

Im not worried about the blow back nor the recoil, I just dont want my brass, nor the moving components destroyed because its over gassed. Im still new to rifle suppressors, and all the other guns ive shot them on were piston or adjustable gas, so of course they ran flawlessly. Im sure the DD, Colt and many others will run fine suppressed, and I bet even the piston and adjustable guns could be fine without being adjusted, I just wanted to run the gun in an "optimal" setup for being suppressed, and I didnt know if the shorter 10.3 inch MK18 would be fine as is, or if there is a better SBR upper that is preferred for suppressed fire. I think the MK18 is one of the best looking uppers so I didnt want to ditch it if its fine, which it sounds like it will be. Now that ive shot suppressed, I will likely never shoot without them on, so I figured it would be best to have guns that run well that way.

I also just snagged a new Noveske Recon in a trade, debating if im going to set it up for this too, but it has the NSR rail so I dont think I can install the switch block.

to the other replies, im gonna see how it runs as is when I get a chance to hit the range before I change it, but honestly if I have to modify it, id likely just sell it and either build something from scratch, or buy a piston upper.
 
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I think it's all about preference. Any quality AR will run piston or gas so long as it's set up correct. I snagged up my new 10.5" LWRC A5 upper which will go on my L-Dub lower. 2 position gas block, but I am a piston fan, nothing against gas, just my preference.


Who is John Galt?
 
The NSR is machined perfectly for cuts over the main gas port locations to accommodate a switchblock. That is a ridiculous set up actually if you wanted to make that happen...

I want to, but my rifle came with the 13 inch NSR rail, I looked on Noveskes website and didnt see an extended switchblock like some companies make for the gas control so looks like id have to select what I wanted and put the rail back on. Id say most of the time it will be suppressed, but id hate to have to yank the rail any time I wanted to shoot without it.

edit - used my google-fu... looks like they arent compatible unless I want to do what this guy did... which I dont
http://www.ar15.com/forums/t_1_5/14...nd_a_unicornish_NSR__Please_step_inside_.html
 
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You might be thinking about the SWS rail, not the NSR. Here's the SWS with Noveske Switchblock:

IMG_2668.JPG


IMG_2671.JPG


These rails seem to be impossible to get these days.

A couple of shots of NSR forends:

IMG_2891.JPG


They're too skinny to get anything but a low profile gas block inside, as you can see:

IMG_2892.JPG
 
My patented, tool-less block works fine with the DD MK18. It is currently the only tool-less option currently available that uses a standard, un-modified gas tube.
Here is a picture of mine:
SakerDD-MK18-Govnah-1024x261.jpg


Just use a bullet to move the regulator plate:
Merrill-Govnah-Regulator-Plate-Adjustment-618x412.jpg


Here is a video of it running in full auto:
 
Not sure how I missed replying, sorry bout that. No, I wasn't referring to the already cut SWS. I was suggesting that the NSR lines up pretty well over the gas port locations to have it milled out to accommodate the Switchblock. That would be a pretty unique set up.

OP, I definitely wouldn't want to do cut a rail like that guy did either. However, clearly he had no clue what he was doing. With a little attention to detail and employing the appropriate tools, it can be machined looking like it came from the factory that way. Here's a URX 3.1 I did for a guy's 14.5" ML. The cut needed to be a little long based off of the way the KAC handguard is installed, but any one piece rail designed to install with a barrel nut going on before the rail can be machined to fit perfectly just like the SWS...


 
I'm not one for piston guns or BLK craze (both shinnannigans IMO). I've had a lmt piston gun, and it was a hemroid and a way over gassed nightmare. Got rid of it. I definitely understand taming the gas and appreciate a well tuned yet reliable gun.

OP: I would run what you have and possibly use a SLR GB if you really need it. But I would keep the DD upper. Screw the piston guns I don't care what they cost or what they promise. I run a dd 11.5 and a 10.5 KMR rail that's rock solid set up with a SLR GB. YES the SLR GBs are well worth it in my opinion for my needs.
 
I also agree with Cobracutter that the Noveske stuff is a bit overpriced considering it's not doing anything more special than the next thing. I will say that I own quite a few items by Noveske however I will not be buying anymore. Not bashing them but I don't see the real need considering other companies are cheaper and putting out top quality like Daniel Defense.
 
After researching a bunch, looking into a pws, noveske and multiple other high dollar adjustable, I found a silly deal on a sig 516 10 inch upper and snagged it... It shoots amazing and absolutely zero recoil with the suppressor, and very little gas in the face on the lower gas setting. Cycled beautiful, so I'd say good purchase!
 

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Nice. Good to hear you ran up on a good set up. You know, seeing this thread got me thinking about the whole 5.56 SBR topic. Back when I was trying to make a call on a 10.5, 11.5, 12.5, and/or go the DI or piston route I couldn't find jack shit comparing them head to head suppressed. Now I have a 8.5" Navy retro-fitted with an XLP kit , 10.5" switchblock, and a 12.5" switchblock. If anyone in the state of CO (or TX where I frequent often) wants to sync up and do some legit comparisons with different barrel lengths, ammo, operating systems, to measure real world variances in accuracy, recoil, effective range, maneuverability, and 20 other aspects anyone might consider personally important for their application - and likely spend months researching - let me know. I'd be all in for participating in that!