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5.56 MCX Virtus Barrel Cutting

17K views 20 replies 10 participants last post by  kyjd75 
#1 ·
Hello all.
Has anyone had their 5.56 MCX Virtus 16" barrel rifle cut down to 10-12 inches? If so, did the rifle still function properly without modifying the gas system? For those that haven't done it, would you expect any issues to arise? I am thinking that if the gas block assembly is the same exact part on the mcx patrol and mcx factory sbr and the position of the gas block relative to the action are the same on both rifles, it should work, but I have been unable to verify either of those.
Any pictures are appreciated.
 
#4 ·
The MCX is gas operated. A shorter barrel, after being cut by your gunsmith, will not be under warranty if it does not operate well with your ammo. A SIG barrel will have SIG's engineering expertise in the gas port--for whatever its worth.

A shorter barrel on the OP's rifle will require a tax stamp for civilian use.

Personally, I would want a SIG barrel on my 300 BLK pistol. I would have confidence in a SIG 5.56 barrel and would like to get on the next time they are on sale.

Bill
 
#5 ·
Hi Bill. I have a registered SBR lower and also a pistol lower I can put the cut down upper on...I was mainly concerned about whether or not the gun would cycle after being cut down. I know some people cut down their gen 1 mcx rifles without any problems but I haven't found anything regarding the Virtus. I'm assuming you meant that the MCX is gas piston operated, not gas impingement..
 
#9 ·
That was definitely a thought, but if the ONLY difference between the factory 16" and factory sbr is the length of the barrel, I can convert my gun and only be out of pocket $65. If I go the other route, I'll have to spend at least $500 for a barrel exchange kit and sell mine for hopefully $300, if that.. I'd be out at $500 up front and maybe recover some later. I will spend the $500 if necessary, but if cutting my barrel will work fine, it seems to be the best option?
 
#10 ·
That was definitely a thought, but if the ONLY difference between the factory 16" and factory sbr is the length of the barrel, I can convert my gun and only be out of pocket $65. If I go the other route, I'll have to spend at least $500 for a barrel exchange kit and sell mine for hopefully $300, if that.. I'd be out at $500 up front and maybe recover some later. I will spend the $500 if necessary, but if cutting my barrel will work fine, it seems to be the best option?
You should be able to get a barrel for just a little over $400. If you sell your used barrel for say $300, you’re not out that much and you have a brand new un cut barrel. That is what I would do.
 
#15 ·
I had the MCX Virtus 16" barrel cut down to 11.5", measured from the bolt face. I mention 11.5" measured from the bolt face because if you look at the factory MCX SBR (which is advertised to have an 11.5" barrel"), the handguard is even with the muzzle brake. After having mine cut, I noticed that the barrel sticks out past the handguard about an inch. After looking at the factory sbr photo again, I noticed that there is definitely more space between the gas block and muzzle on my gun than on the factory sbr on sig's website. I'm not sure how sig measured the barrel on the factory sbr to come to 11.5" but I would say without a doubt it is more like 10.5". The ATF measures barrels from the bolt face, by sticking a rod down the barrel with the action closed, pinching off the rod, and then measuring the rod. We followed the same procedure when cutting my gun down, and that is how it came out to be about an inch longer than the factory gun.

So far, I have used XM193 and Hornady Black 75gr bthp without any problems on both gas settings, suppressed and unsuppressed. I chose those loads to get something on both ends of the spectrum.

Let me know if you have any other questions.
 
#17 ·
For anyone interested, I had this exact discussion with a Sig rep a few weeks ago, inasmuch as I was trying to acquire a 14.5" barrel. He told me none were available but that I could buy a 16 and have it cut to 14.5. He said that the gas ports were the same size on all of the 16, 14.5 and 11.5 barrels for the MCX Virtus. He offered to backorder me a 16" barrel conversion kit at 20% off. After more friendly discussion, he agreed to let me backorder an entire 16" MCX Virtus at 20% off, which I have done. When it arrives, I plan to send it to John Thomas at Retro Arms Works to have the barrel cut to 14.5. This will give me a "complete" family of 11.5, 14.5 and 16 inch barrel rifles.
 
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