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Posted: 12/31/2016 2:04:20 AM EDT
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I have an Omega 9K suppressor on the way and plan on chopping the barrel on the MPX to the recommended 4.5". Right now, I'm not sure which mounting method would be better... 3-lug or Direct Thread. Is 3-lug absolutely necessary?
If I go the 3-lug route, I would also like 1/2x28 thread at the end of the barrel (just like you would see on the end of a MP5 and has a thread protector) so I can switch between using the 3-lug and direct thread mounting methods. How do I do this? Would I need to get my barrel cut shorter than 4.5" to account for a 3-lug? 
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Go forth and read:
Octane is in, I want to suppress my MPX If you are chopping the barrel, you get to pick the threads.... 1/2x28 is most widely used, and gives most mount options. As for threaded 3-lug, in my mind, thats more moving parts to come loose that you dont need. There is a reason that particular thing is not widely used. If you need to take the can off a lot, or use it on many hosts, then 3-lug, otherwise direct thread. |
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I can get it threaded for 1/2x28 now and add a 3-lug adapter later, correct? My main concern is that direct thread is less secure and could come loose. Is there a way to thread on a suppressor tightly? Many use a layer or so of Teflon tape on the barrel threads if you are concerned about it backing off. And yes, you can send off the barrel to be cut and threaded 1/2x28 and direct thread the suppressor. Then if you decided you want to switch it to 3lug you can get a 3lug mount for the barrel and rockset that on. |
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Many use a layer or so of Teflon tape on the barrel threads if you are concerned about it backing off. And yes, you can send off the barrel to be cut and threaded 1/2x28 and direct thread the suppressor. Then if you decided you want to switch it to 3lug you can get a 3lug mount for the barrel and rockset that on. Thank you for the clarification. So, all the pictures I'm seeing of the MPX with a 3-lug... That was screwed on to the threads and rockset on? Or are the 3-lugs an actual part of the barrel itself? |
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I just went through this with my MPX, and went direct thread mainly due to the cost of a 3 lug setup..Eventually, I will do 3 lug, but not for many, many months.
If you have the funds for a 3 lug setup I'd just go ahead and do that. With direct thread, it will work loose. I notice that between 25 and 50 rounds I need to tighten up the suppressor a little bit. Right now I am experimenting with blue loctite, mainly because thats what i had on hand...couldn't find the teflon tape and didn't have rocksett. Went through about 50 rounds a little while ago and the suppressor did not show any signs of loosening. I imagine if it gets really heated up, the loctite will work its way loose, but its unlikely ill shoot enough at one time for that to happen. Have fun... :) |
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Thank you for the clarification. So, all the pictures I'm seeing of the MPX with a 3-lug... That was screwed on to the threads and rockset on? Or are the 3-lugs an actual part of the barrel itself? Correct. Those are all adapters that are threaded onto the MPX barrels. They are not an actual part of the barrel like you see with an MP5 or B&T APC/P26 |
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That barrel shown has the lugs and threads directly machined onto the barrel. To get what you want on an MPX barrel, what you would need is a 3-Lug adapter that is threaded all the way through with the tip cut down to allow the barrel threads to be exposed when the adapter is shouldered onto the barrel. I don't know of any 3-Lug adapters (TROS, Griffen, HKparts, Gemtech, etc) that are short.
All my 9mm Carbine and SBR barrels are all 3-Lug including my MPX which hosts a Omega 9K with both the Silencerco and Rugged 3-Lug mounts. All my 3-Lug mounts lock up tight with some being much tighter due to higher spring tension in the mounts. I have never had any issue with the 3-Lug. |
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That barrel shown has the lugs and threads directly machined onto the barrel. To get what you want on an MPX barrel, what you would need is a 3-Lug adapter that is threaded all the way through with the tip cut down to allow the barrel threads to be exposed when the adapter is shouldered onto the barrel. I don't know of any 3-Lug adapters (TROS, Griffen, HKparts, Gemtech, etc) that are short. All my 9mm Carbine and SBR barrels are all 3-Lug including my MPX which hosts a Omega 9K with both the Silencerco and Rugged 3-Lug mounts. All my 3-Lug mounts lock up tight with some being much tighter due to higher spring tension in the mounts. I have never had any issue with the 3-Lug. Good to know. So, if I request my barrel to be cut to 4.5" and then install a 3-lug adapter, how much length is added? I'm wondering if I should request the barrel to be cut slightly shorter so that after the 3-lug adapter is installed I come out to 4.5". |
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That barrel shown has the lugs and threads directly machined onto the barrel. To get what you want on an MPX barrel, what you would need is a 3-Lug adapter that is threaded all the way through with the tip cut down to allow the barrel threads to be exposed when the adapter is shouldered onto the barrel. I don't know of any 3-Lug adapters (TROS, Griffen, HKparts, Gemtech, etc) that are short. All my 9mm Carbine and SBR barrels are all 3-Lug including my MPX which hosts a Omega 9K with both the Silencerco and Rugged 3-Lug mounts. All my 3-Lug mounts lock up tight with some being much tighter due to higher spring tension in the mounts. I have never had any issue with the 3-Lug. Forgot to ask... Why would you use the Rugged 3-lug mount when the Omega 9K comes with its own 3-lug in the box? |
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Omega 9k does not come with a 3-lug mount, but Silencerco will sell you one. Its huge. Thats why people would use a Griffin or a Rugged 3-lug mount, its shorter than factory.
In ALL cases a mount will thread into the suppressor and something will thread on the barrel. So you are talking about 2 sets of threads, no matter what method you want. Silco Factory available mount: 
Griffin: 
Rugged: 
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Omega 9k does not come with a 3-lug mount, but Silencerco will sell you one. Its huge. Thats why people would use a Griffin or a Rugged 3-lug mount, its shorter than factory. In ALL cases a mount will thread into the suppressor and something will thread on the barrel. So you are talking about 2 sets of threads, no matter what method you want. Silco Factory available mount: http://modernwarriors.com/wp-content/uploads/2016/03/SilencerCo-3-Lug-Mount-1.jpg Griffin: https://cdn3.volusion.com/zwlmq.eyhrp/v/vspfiles/photos/REVQDK-2.jpg? Rugged: http://www.silencershop.com/media/catalog/product/cache/1/thumbnail/480x/17f82f742ffe127f42dca9de82fb58b1/r/u/rugged_obsidian_3-lug_front__1200x800.jpg Thanks for the explanation. What brand 3-lug adapter do you personally recommend. Looks like there are some options. Preferably one with threads at the end of it. |
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Thanks for the explanation. What brand 3-lug adapter do you personally recommend. Looks like there are some options. Preferably one with threads at the end of it. I personally have not seen any 3lug adapters that are also threaded at the end. I guess in theory someone could thread one for you if there is enough meat and a way to ensure they stay concentric. As far as adapters people have had great luck with Tros, HKParts and Griffin Armament. |
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What he said:
TROS, HK-Parts and Griffin are the big 3lug adapter manufacturers. None of them, or anyone I know of sells an off the shelf threaded one. I believe that arrangement is called a Navy 3-lug adapter. As seen on MP5-N guns. Since they are hard to find now, you can assume there is not the demand. The MP5 barrel in your image, the 3-lug is cut into the barrel, and the end threaded, like an average barrel. MPX does not have meat for that, so not an option. Here is your average TROS adapter (most all look the same) 
The process you would engage in, get a good machinist, I have had good luck with Morgan at http://class3machining.com/ . They will cut and thread your barrel, the threads are cut Extra long, like 1.5". If using a normal adapter (as above), they would cut the nose off the adapter. The lugged part of the adapter then threads on-- like a collar, and where that nose would have been remains bare barrel threads. Then fit a proper sized thread protector, as shown in your original picture. Needless to say the length of threads has to be just right. You could not do this with factory threads, as all the other adapters are meant for. A quick google shows one potential source for an adapter/protector combo: http://www.investmentgradefirearms.com/igf-us-made-products-navigation-page/mp5-3-lug-adapters/ 
Even with that, you will need your machinist to cut extra long threads. |
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Absolutely no contest. Go with the 3-lug. A modern 3-lug suppressor mount requires very little service and stays installed rock solid. The latter cannot be said for a thread-on can, which absolutely will loosen with use.
The threads on the MP5-N barrel are due to the fact that the suppressor 3-lug mount designs of that era (late 80s/early 90s) were not of the same design/quality as the options today. A direct thread can was preferable. Today this is simply not the case. I have a SWR qd3k that is around 15 years old and has somewhere between 7-10,000 rounds (all fullauto) through it. It has never loosened, never become bound/stuck. In fact it never gave me any trouble until I recently noticed that the first blast baffle is totally filled with carbon and the remaining baffles have so much crud it is likely kissing the projectiles as they pass. |
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As said, if you are going to use the can on a pistol, and so need to often remove the 3-lug mount, you sort of loose the advantages. If you are not, and so can rock-set the mount on the barrel and torque the mount in the can, you will be good with 3-lug.
Again, there will always be 2 points of threading with a 9k... can mount and barrel. whatever you put on the barrel can be semi-permanent. How permanent you make the mount on the can--- that depends on how often you want to change it! |
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The shortest way to mount an Omega 9k is with the Harvester direct thread mount. When it comes to 3 lug, there are at least 3 brands which will fit with varying length. The Silencerco factory mount is the longest. All that info is covered in the other thread. Is the Harvester direct thread mount (AC633) compatible with the Omega 9K? The only Omega 9K direct thread mount I see on SilencerCo's website is the AC149. How much shorter is direct thread versus using the SilencerCo 3-lug adapter? I read somewhere else on the Interwebs that using the Griffin 3-lug mount with their Omega 9K/MPX resulted in POI shift (not to mention would not be supported by SilencerCo). Lastly, anybody have pictures of their MPX shortened to 4.5" with either direct-thread or 3-lug mount for comparison purposes? |
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In Lead We Trust is making a 4.5" threaded/tri-lug barrel for the MPX for $275, but you'll have to use the gas block from the factory barrel. Sig has a Part number (CALX-MPX-4B-9-G2) for the 4.5" caliber exchange kit, Lanbo has it priced at $458
https://www.inleadwetrust.com/collections/mpx-parts/products/tri-lug-4-5-barrel-for-sig-mpx I've got one on order. My current setup is MPX-P that has been SBR'd and I have a Rugged Obsidian suppressor with AC1526 (Silencerco Octane) fixed barrel mount. I don't like this setup because the MPX barrel is LH-threaded and the suppressor is RH-threaded. It's difficult keeping everything finger-tight at the range. So now I'll need to buy fixed barrel spacer for I can use piston the suppressor was shipped with. I plan eventually on getting a tri-lug mount though. |
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Wow that setup from ILWT is pretty nice. My plan was to ship out my barrel have it chopped threaded etc and then rocksetn on a 3lug. But with the price of chopping and adding the 3lug it seems better to go with this setup. Cheaper and its solid one piece. That barrel is well over double the cost of getting a barrel threaded and buying 3 lug adaptor. If it came with a gas block for that price i'd be interested in having a reasonably quick barrel length conversion but in honesty i'd never use the longer barrel and with no gas block i'd really never bother switching back to the original barrel. But if some people feel having a threaded devise is an issue then this would be an option. |
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In Lead We Trust is making a 4.5" threaded/tri-lug barrel for the MPX for $275, but you'll have to use the gas block from the factory barrel. Sig has a Part number (CALX-MPX-4B-9-G2) for the 4.5" caliber exchange kit, Lanbo has it priced at $458 https://www.inleadwetrust.com/collections/mpx-parts/products/tri-lug-4-5-barrel-for-sig-mpx I've got one on order. My current setup is MPX-P that has been SBR'd and I have a Rugged Obsidian suppressor with AC1526 (Silencerco Octane) fixed barrel mount. I don't like this setup because the MPX barrel is LH-threaded and the suppressor is RH-threaded. It's difficult keeping everything finger-tight at the range. So now I'll need to buy fixed barrel spacer for I can use piston the suppressor was shipped with. I plan eventually on getting a tri-lug mount though. I really want this barrel. BUT...I want a complete barrel assembly. Anyone know if Sig sells the MPX Gas Block? |
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I really want this barrel. BUT...I want a complete barrel assembly. Anyone know if Sig sells the MPX Gas Block? Seems like Sig will be getting the caliber exchange kit to distributor's soon which includes the barrel and gas block, they have been popping up multiple places. I went with ILWT since I probably would only use 4.5" ILWT barrel https://lanbosarmory.com/index.php?main_page=product_info&cPath=118&products_id=36826 http://grabagun.com/sig-sauer-sauer-calx-mpx-8b-9-g2-cal-x.html |
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That barrel is well over double the cost of getting a barrel threaded and buying 3 lug adaptor. If it came with a gas block for that price i'd be interested in having a reasonably quick barrel length conversion but in honesty i'd never use the longer barrel and with no gas block i'd really never bother switching back to the original barrel. But if some people feel having a threaded devise is an issue then this would be an option. well pricing wise its a little higher i suppose.. but i think the overall issue works... one of the pros is that you can retain your factory barrel if you wanted to switch back to it for any reason. i also like it because i dont have to rocksett on the 3lug adapter it would be a nice solid setup. i think its worth it to have an extra barrel for a little more than normal chopping/ordering a 3lug price BUT i think i would wanna hear from some people that used the ILWT setup. |
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I expect they'll sell you one. When they ship it is a whole other story. Quoted:
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I really want this barrel. BUT...I want a complete barrel assembly. Anyone know if Sig sells the MPX Gas Block? I expect they'll sell you one. When they ship it is a whole other story. Sig is not able to sell the gas block separately...I just got a reply on my inquiry. |
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