Will the Sig MPX run an RDIAS?

Machineguntony · June 13, 2015, 12:56 AM

Does anyone know if the Sig MPX pistol or SBR will run in full auto with an RDIAS?

I can't find any forum threads online regarding this issue. Does anyone know of a discussion, or has had personal experience running the MPX with an RDIAS?

I hope that Sig doesn't neuter the bolt, as I imagine the bolt would be of a proprietary design, or perhaps different from a standard 9mm AR bolt. I am going to the new Bass Pro Shop tomorrow and check out the internals, if Bass Pro has the gun in stock.

It would be so awesome if the gun could run with a RDIAS.

5.56RifleGuy · June 13, 2015, 09:54 AM

It may, but since its not an ar 15 you could not do it legally.

People tried doing this with fnc sears in scar rifles. They will work, but the ATF said you cant do it.

Willie Lowman · June 14, 2015, 09:14 AM

The painful truth ^^^

dakota.potts · June 14, 2015, 11:49 AM

What's the parts interchangeability between the two? With your resources, Tony, could you maybe not have the MPX built onto an AR receiver?

Sharkbite · June 14, 2015, 12:05 PM

Me not being familiar with MG rules very deeply, can someone explain why this is not legal?

With a registered sear, that is designed to be moved to different hosts, why am i limited to AR platforms?

Willie Lowman · June 14, 2015, 12:17 PM

Sharkbite, the great guys over at ATF tech branch dicided that sears can only be used in what they call "legacy" guns. That means an HK sear or trigger pack can only be used in a HK 91, 93, 94, or a clone of one of the guns from that pattern. (The 23E thankfully is included in the HK legacy)

AR-15 RDIAS can only be used in a AR-15 lower.

The FNC sears can only be used in an FNC because those stone blind idiots... I mean, great guys, said that the SCAR is not from the FNC legacy and so the FNC sear can't go in a SCAR.

Long story short, it's because the ATF said so.

Sharkbite · June 14, 2015, 07:04 PM

Ahhhh....

Well that makes perfect sense. Thanks for the info

James K · June 14, 2015, 10:53 PM

FWIW, we have the great FDR to thank for the NFA; and it was only by the hard work of a few Representatives and Senators, with a little help from the few thousand NRA members, that we didn't have the NFA extended to all firearms and ammunition, complete with registration and transfer taxes. (The original administration bill put $1000 on a MG, $200 on a handgun, $100 on a rifle and $20 on a shotgun, plus $5 tax on every centerfire cartridge. This at a time when a working man might make less than $5 a day, if he were lucky enough to have a job at all.)

Jim

Skans · June 15, 2015, 01:26 PM

It wouldn't work anyway. The MPX has a folding stock which tells me that it uses a much different bolt carrier than an AR. The Bolt Carrier won't be designed to work with a DIAS. Everything internally is going to be off-spec for a DIAS and I doubt the fire control parts are the same as the M16.

RCT · June 19, 2015, 07:53 PM

I took a quick look at the internals at Shot Show and some of the parts look to be simple AR stuff.

They however employed a rotating bolt and there is a 'shelf' that blocks proper full-auto function. Some work would have to be done in order to get it to fire full-auto.

I should have an MPX in my hands on Tue. I can take a better look then.

RCT · August 20, 2015, 11:30 AM

I looked inside an MPX and it does have a metal shelf blocking the use of full-auto parts. However, it appears to have a standard AR-15 fire control group (trigger, sears and such).

June 13, 2015, 12:56 AM	#1
Machineguntony Senior Member Join Date: June 22, 2013 Posts: 1,277	Will the Sig MPX run an RDIAS? Does anyone know if the Sig MPX pistol or SBR will run in full auto with an RDIAS? I can't find any forum threads online regarding this issue. Does anyone know of a discussion, or has had personal experience running the MPX with an RDIAS? I hope that Sig doesn't neuter the bolt, as I imagine the bolt would be of a proprietary design, or perhaps different from a standard 9mm AR bolt. I am going to the new Bass Pro Shop tomorrow and check out the internals, if Bass Pro has the gun in stock. It would be so awesome if the gun could run with a RDIAS. __________________ Sent from Motorola DynaTac 8000x

June 13, 2015, 09:54 AM	#2
5.56RifleGuy Senior Member Join Date: May 9, 2010 Location: USA Posts: 1,212	It may, but since its not an ar 15 you could not do it legally. People tried doing this with fnc sears in scar rifles. They will work, but the ATF said you cant do it. __________________ Sic Semper Tyrannosaurus

June 14, 2015, 09:14 AM	#3
Willie Lowman Senior Member Join Date: March 5, 2009 Location: Uh-Hi-O Posts: 3,006	The painful truth ^^^ __________________ "9mm has a very long history of being a pointy little bullet moving quickly" --Sevens

June 14, 2015, 11:49 AM	#4
dakota.potts Senior Member Join Date: February 25, 2013 Location: Keystone Heights, Florida Posts: 3,084	What's the parts interchangeability between the two? With your resources, Tony, could you maybe not have the MPX built onto an AR receiver? __________________ Certified Gunsmith (On Hiatus) Certified Armorer - H&K and Glock Among Others You can find my writings at my website, pottsprecision.com.

June 14, 2015, 12:17 PM	#6
Willie Lowman Senior Member Join Date: March 5, 2009 Location: Uh-Hi-O Posts: 3,006	Sharkbite, the great guys over at ATF tech branch dicided that sears can only be used in what they call "legacy" guns. That means an HK sear or trigger pack can only be used in a HK 91, 93, 94, or a clone of one of the guns from that pattern. (The 23E thankfully is included in the HK legacy) AR-15 RDIAS can only be used in a AR-15 lower. The FNC sears can only be used in an FNC because those stone blind idiots... I mean, great guys, said that the SCAR is not from the FNC legacy and so the FNC sear can't go in a SCAR. Long story short, it's because the ATF said so. __________________ "9mm has a very long history of being a pointy little bullet moving quickly" --Sevens

June 14, 2015, 12:05 PM	#5
Sharkbite Senior Member Join Date: November 4, 2013 Location: Western slope of Colorado Posts: 3,679	Me not being familiar with MG rules very deeply, can someone explain why this is not legal? With a registered sear, that is designed to be moved to different hosts, why am i limited to AR platforms?

June 14, 2015, 07:04 PM	#7
Sharkbite Senior Member Join Date: November 4, 2013 Location: Western slope of Colorado Posts: 3,679	Ahhhh.... Well that makes perfect sense. Thanks for the info

June 14, 2015, 10:53 PM	#8
James K Member In Memoriam Join Date: March 17, 1999 Posts: 24,383	FWIW, we have the great FDR to thank for the NFA; and it was only by the hard work of a few Representatives and Senators, with a little help from the few thousand NRA members, that we didn't have the NFA extended to all firearms and ammunition, complete with registration and transfer taxes. (The original administration bill put $1000 on a MG, $200 on a handgun, $100 on a rifle and $20 on a shotgun, plus $5 tax on every centerfire cartridge. This at a time when a working man might make less than $5 a day, if he were lucky enough to have a job at all.) Jim

June 15, 2015, 01:26 PM	#9
Skans Senior Member Join Date: November 20, 2008 Posts: 11,132	It wouldn't work anyway. The MPX has a folding stock which tells me that it uses a much different bolt carrier than an AR. The Bolt Carrier won't be designed to work with a DIAS. Everything internally is going to be off-spec for a DIAS and I doubt the fire control parts are the same as the M16.

June 19, 2015, 07:53 PM	#10
RCT Junior Member Join Date: June 19, 2015 Location: Michigan Posts: 10	I took a quick look at the internals at Shot Show and some of the parts look to be simple AR stuff. They however employed a rotating bolt and there is a 'shelf' that blocks proper full-auto function. Some work would have to be done in order to get it to fire full-auto. I should have an MPX in my hands on Tue. I can take a better look then. __________________ FFL w/ SOT Check out our extensive online firearm and shooting sports store here: https://www.redcircletactical.com/

August 20, 2015, 11:30 AM	#11
RCT Junior Member Join Date: June 19, 2015 Location: Michigan Posts: 10	I looked inside an MPX and it does have a metal shelf blocking the use of full-auto parts. However, it appears to have a standard AR-15 fire control group (trigger, sears and such). __________________ FFL w/ SOT Check out our extensive online firearm and shooting sports store here: https://www.redcircletactical.com/