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MCX Rattler in 5.56mm Flash Hider Removal

35K views 70 replies 17 participants last post by  klugey1  
#1 ·
I am posting this question because the other threads I have seen do not seem to answer the questions fully, or at least specifically for my model Sig. I have a new Sig Sauer MCX Rattler in 5.56 Nato caliber. This is the pistol with the 5.x" barrel. I have ordered a Noveske Flash Hider KX5 Pig 1/2"-28. My intent is to replace the EOM flash hider with the Noveske. I believe I understand the answers to these questions, but want to be clear before I begin.

1) Is the barrel thread for this pistol model left hand or right hand thread?
2) Is the flash hider pinned onto the barrel for this pistol model?
3) Any quarks I need to know about before removing the OEM flash hider?

Thanks!
 
#3 ·
There were a few post that concluded the flash hider was pinned & welded for the 5.56 Ratter model. They've also mentioned that there was really no threads under the oem flash hider. Don't know if it was from experience or a response from Sig CS. Here is the link: https://sigtalk.com/sig-sauer-rifles/338258-5-56-rattler-2.html

Hopefully they are able to chime in to this thread and validate. Good luck!
 
#4 · (Edited)
All,
I hate leaving a thread unfinished. It leaves future researchers up-in-the-air on the questions being posed. Although a considerable pain, I have finally received a response from Sig Sauer that mostly answers my questions. And those answers are not what I had hoped for. Here are my questions and the responses from Sig.

Email: Me to Sig on 6/18/20-
1) Does Sig make a replacement gas piston assembly for the Sig MCX Rattler in 5.56? My gas piston assembly is totally different design than those replacement assemblies on your website?
2) I wish to replace the OEM flash hider. I do NOT want to use a suppressor. Just a different flash hider. The OEM flash hider appears to be pinned.
< Is the OEM flash hider pinned and also welded or braised onto the Rattler 5.56 barrel?
< Is the barrel threaded? If so, what thread & direction?
< If the barrel is not threaded, what is the barrel exterior diameter under the OEM flash hider?
3) It seems that from looking at the assembly, the gas system does not function from a hole in the lands & grooved portion of the barrel. Rather functions from a smaller diameter space located between the barrel crown and innermost portion of the flash hider? So, would removing the OEM flash hider and installing a different flash hider affect the gas operation?
4) I do not want to screw up the firearm & will not change the flash hider if there would be issues. I wish to know what those issues would be before I decide a course of action?

Response Email: Sig to Me on 6/24/20-
1) We have not built a (gas) kit for these yet, and we only have parts for warranty. Nothing for retail sale yet. You have a limited production item. Marketing is working on getting these out, but is delayed due to the virus.
2) It is pinned and welded. Yes, a standard ½ X 28 thread.
3) Most likely but not in a dramatic way.
4) We do not recommend removal of the flash hider currently installed by the factory. It’s a $600 mistake (Cost of a new 5.56 barrel system) to correct if things go wrong.

So, not all answers I liked, but better than no answers at all. During phone calls to Sig before the email response, they did say that the 5.56 Rattler is NOT designed for use with a suppressor. I am sure that is why the pinned & welded barrel.

My reasoning for these questions in the first place is because as anyone who has shot a Rattler knows, that barrel is very — very short! I had hoped that by replacing the OEM flash suppressor/hider with something like a Noveske KX5 to lessen both concussion & the chances of blowing your fingers off!

Having said all that, now that I have shot it some & placed a Magpul M-Lok Hand Stop Kit on the bottom rail, I feel more confident that I will retain all my fingers.

I may yet have the OEM flash hider removed and try a replacement. Would be gambling. Especially with the funky gas port setup……….

I have attached a drawing of how to me, the muzzle end of the 5.56 Rattler barrel appears to be designed. Drawing is not to scale. Just provided to give an understanding how the muzzle end of the Rattler system works. Strangest thing I have ever seen.......
Image


Well, for some reason I cannot get the system to see my linked image. So here is the URL: http://brucevarner.com/Drawing1.jpg
Thanks!
 
#7 ·
Good summary [mention]btvarner [/mention]— thanks for sharing!

I’ve taken to researching a clamp-on thread adapter to sit atop the factory break. Email out to Witt Machine regarding their model and whether it can be chopped down for the 3/4” overhang we have to work with and still function appropriately. Would be REAL NICE to put a simple blast shield/redirect or to stretch that fireball out a few inches.

https://www.wittmachine.net/custom-clamp-on-threaded-adapter.html
 
#12 ·
Don’t have a photo readily available, but took a look at mine last night and it appears the muzzle device is either welded to or a component of the gas block. In any case, it’ll take a bit of work to remove and thread without damaging the block itself. My two cents of course, sans experience.


Sent from my iPhone using Tapatalk
 
#25 ·
Rexorcist, the flash hider IS pinned & welded/brazed. You will break it if you continue. I have a letter from Sig confirming this! Plus! Assuming your weapon is 5.56 NATO version, you will be getting into a real problem if you try & change the flash hider. The 5.56 version is gassed different than the 300 BO version. This is why they say the 5.56 version cannot be suppressed. The gas system is different between the two! Any replacement flash hider would need to match exactly the size & placement of the OEM gas system for the MCX to function for a second & subsequent shots. The MCX 5.56 version gas system is in/at the flash hider...............

Could it be done? Probably, but is it worth the effort, considering the minimal improvement you would receive would be only a slight better noise reduction. Could you modify a suppressor to function? Maybe. But don't you think that Sig would have done that as an option for the military if it was reasonably doable? The problem is in the gas system used in the 5.56 version.

There is advice elsewhere on how to remove pinned & brazed flash hiders from barrels But you are opening up a can of worms. Not to mention that YOU instantly become a felon, when you remove the hider................
 
#27 ·
Steve Shannon: You are correct. My mistake. I confused discussions I was having about legalities on a "rifle" that removing the flash hider caused the barrel to be under the legal length for that other rifle. I also did not read far enough back. My bad. He still needs to understand the gas system issues with doing this............ I don't think that just replacing the flash hider is going to work without additional modifications. I hope he succeeds!!!!

DansSIGs: Have you actually removed the flash hider on an MCX in 5.56????? Just wondering.