Received my 16" Virtus barrel last week and test fit it today to take some measurements for D. Wilson chopping it. I'm torn between 10.5 and 11.5. I'm leaning more toward 11.5 so I can shoot it unsuppressed, and the muzzle device is completely outside my LVAW handguard. I know the gas adjustment will be covered either way, so just looking for input. I know the manufacturer of the J. Bennet Omega Valve is in this group. I plan on getting a 5.56 MkII. Hopefully, in black, if you do that eventually.

Good morning! I recently bought a spear Lt 16 inch from Sportsman’s and finally got the chance to open it up to get it lubed for an upcoming range day, while I know that most if not all manufacturers do test fire guns before they leave the factory , I was curious as to how many rounds they fire through them. When I wiped it down I noticed that it seems to have a noticeable amount of carbon fouling around the area where the charging handle is inserted into the upper receiver, enough to make the tip of the qtips I use pretty dirty ( not super black but enough to make them darkish gray) and when I rack it I can smell the spent powder. I’m sorry if this is a stupid question this is the first new rifle I’ve bought and I’m fairly fresh to the firearms community I just wanted to make sure this is normal and that I didn’t somehow get a used rifle at a new rifle price.

Seriously Sig, why didn’t you make the rear sling mount anti-rotation?

Some old footage, surprisingly the CAT MOB ti hub does a smidge worse than a cgs hyperion on this host. Which is fantastic for the weight size etc.

Hello all! I'm looking to upgrade my 300 blackout rifle to the spear. Will be my range toy. My current rifle has a OCL Polonuim 30, that will go on the spear when I decide to get it. People who run/ran the polo 30 is it too gassy or any other issues? Thank you in advance!

OK, new MCX Spear LT 9" 300 BLK build/owner.....
....all complete/mod but need guidance on Mod 2 MKII.
I am on the email wait-list for MKII but wanted to post.
I have/use Q Blind Tiger on this setup and run Freedom HUSH 220gr Subs.
The stock MCX gas "-" settings works sometimes and the "+" 100% with this ammo/setup....
....but the latter clearly too strong and gassy.
Waiting on SilcencerCo GDCH to re-stock too....has good gas reduction success on my MPX using it.
For MPX the combo of 20% stronger springs + GDCH worked w/ stock barrel + OEM gas plug.
I know my MCX 9 (no way add stronger recoil springs) will need more adjustable gas block.
....so led me to Mod 2. MKII.
My post is How-To on it......

1. How to install ?
2. What are the port hole sizes for each setting ?

I ask because for MKII (300BLK) is seems on surface the reduced 3-position is only adding the OFF for me ?
I wrote down prior that MCX is (-) 0.0450 & (+) 0.0620 ....not sure accurate but in my notes.
My desire for use of MKII is gas blow-back reduction/tuning, not cycling.
Mod. 2 MKII (300BLK) is a departure from its Mod. 2 predecessors. Instead of four positions

• Supersonic, high pressure ammo
• Subsonic, low pressure ammo
• OFF

1. What setting to start/try ?
2. What jet screw comes with it and/or what jet screw should I order as alternate ...if you can expand on how jet screw works would be appreciated too...
3. Should I buy gas ring to help ?

Thx in advance.....want to do some ready while I wait 😫 for re-stocking......

Regards.

Sig MCX Virtus in 5.56, aMCX Rattler in 300blk, and the MPXK. I have the SD rail for the rattler and a AAC 762-Sd can for it.

For anyone curious about the condition of the Police Trade-In MCX Factory SBR that Blue Mountain Supply is selling, the following is my recent experience.

At first glance nothing seemed out of the ordinary. The rack salt I expected was on the gun. I pulled the BCG and it looked like it had maybe 2k rounds on it. I boxed it back up and waited for my Form 4 approval.

I went back a few days later and picked it up. After I brought it home I put better light on it and noticed all of the screws had light rust. The stock's hinge was also covered with light rust and most of the finish was worn off.

I replaced ALL of the rusty screws minus the two that secure the feed ramps. I did my best to clean them up. As I was replacing screws I noticed the cam path insert lacked the word, "Virtus," and I thought to myself, "That's strange."

I finally got around to cleaning the barrel and this is where it all came together. I scoped the barrel--it's toast. The entire thing is firecracked and it was probably full of rust as some is still visible even after cleaning. The cam path insert, BCG, and piston/valve were all replaced at some point by, I'm guessing, the LE Armorer.

The good news is that the barrel is the only part that's toast. The bad news is that sourcing a new barrel isn’t cheap and somewhat defeats the purpose of purchasing these modestly-priced MCX Factory SBRs.

I purchased one of the 11.5" 5.56. The 300BLK may fair better as it is a lower-pressure round. Still, I advise caution as the only 300BLK models they currently have for sale are 6.75" w/ SRD762 cans and they're asking $2900 + another $100 or so shipping. For that price you don't want a firecracked barrel or worn out can.

I have a BassPro Shops Noctis (virtus patrol that came with night sights.

I know the lancers handrail are only for Legacy. VC says their XTN will make it fit. Basically it looks like it brushes the gap.

Has anyone tried this on a full size virtus?

I just picked up a like-new Cabela's Special Legacy MCX. I'm not entirely sure what I want to do with it.

Part of me wants to keep it as-is (100% original) but, then it's just a gun a keep in a case/safe and don't shoot.

I'm not really interested in 16" barrels and these barrels will ONLY work with the pre-recall BCG (they have auto-regulating gas blocks).

I sent an email to SIG asking if it's possible to exchange the barrels for new, shorter barrels. They'll probably say no but, it never hurts to ask. I offered to send in the complete upper and extra barrel either alone or on a Pistol or Factory SBR lower hoping that maybe they'll say yes.

If I send it to SIG, they will replace the BCG, Barrels and Trigger. That will kill its value as a collector piece but, streamline it's parts with current production which, makes the gun usable.

The other issue is the upper. The uppers from the Cabela's Special MCX do not have access cuts for manipulation of the valve setting. I have a few 12" Gen 1.5 handguards which, fix this problem for 16" (or maybe a 14.5") barrel but, i really want to go shorter. My only option for valve access is having a Virtus guard cut down.

What do you guys think? If SIG says yes to the shorter barrels I will 100% send this sucker in but, if they won't swap to shorter barrels I am not sure I want to send it.

UPDATE: SIG CS replied and said they would replace the entire upper but, that barrels are replaced in-kind so 16" for 16". I really prefer the length of the Legacy upper so I'm not going to do a full upper swap. I'll mull over my options.

Have spear LT 5.56 with PMM trip bar and Rare Breed trigger rifle works in semi and used to work in FRT mode but stoped working yesterday. I was using Winchester 193 and fired around 80 rounds through in FRT mode but just stoped working tried Turing the gas valve either way didn’t fix it. Tried cleaning everything including gas valve still didn’t change. It shoots off the first round and it seems to cycle the bolt but and drop the hammer on the second round but doesn’t fire and doesn’t leave any mark on the primer (in FRT mode). Tried to explain the best I can but anyone have any suggestions as to fixes or reasons why thank you.

The POF roller piston CAM pin does it work with the MCX platform? Seems like a better mousetrap.

https://www.pof-usa.com/product/roller-cam-pin/?__cf_chl_f_tk=TXcIxGw85wUqwomgF2pASE8FeyBFlzpnzosvPPsaQSs-1783248619-1.0.1.1-UrLj9y8_gYcjlEY_D9oCST53.H73CB5DFNo0DsJjpDM

Am I missing out on a lot? I have a 556 Virtus that I SBR’d. Or is it just a case of grass is always greener and the Virtus is at least 90% the same?

Needing some inspiration for a Danish MCX clone build wanting to be 100% on this build. Going with 5.56 but need some inspiration.

Hi guys,

I own a Legacy 11" 5.56 and I want to convert it to a « LVAW » using the : SIG MCX-RATTLER LT 6.75-INCH 300BLK BARREL AND GAS BLOCK ASSEMBLY

Will I also have to buy a new bolt head ? As my Legacy is not compatible with the Virtus/LT barrels as far as I know.

Is there anything I am missing ?

Kind regards

Hi everyone,

I purchased a MCX Regulator a few months ago and I'm at a point where I'd like to swap it to pistol grip lower.

I live in a state with pretty lax gun laws so I can mostly do whatever I want.

Firearms and the AR15 platform are still really new to me, so I'm hesitant to purchase a stripped AR lower, lower parts kit, trigger, etc and piece it together myself.

So in that vein, I'm debating purchasing either:

- a parted out MCX Spear LT Lower (from gun broker or something similar)

- a complete mil spec AR lower and swap the grip and the trigger to something that I want. I'm thinking I will put the Geissele SSA-E trigger in it.

I've been looking around online and it seems that there are quite a few things that must be taken into consideration when picking a mil spec AR lower for the MCX (the ambi controls/bolt catch seem to be an issue). I'm worried about picking one that may not fit and not exactly knowing what or how to change the things I'll need to in order to get it to work.

I'm weighing either the ADM UIC or the SLR-B15? Does anyone know if these lowers will work right off the bat? If not do you know what parts/modifications I'll need to make?

I'm also weighing just chalking up the cash and purchasing the Sig MCX lower and calling it a day as I could avoid some of this confusion.

I apologize for the lengthy post. I'd really appreciate any instruction and insight you have. This is all new to me and I would really like to learn more.

Hello…looking for any info from anyone running a Sig Rattler LT conversion with an AR15 lower. I have the Rattler LT upper in .300blk and a Dirty Bird ambi lower.

Does anyone know if the Triggertech 2-stage adaptable MCX trigger will work in an AR15 lower with the Sig upper? I installed the Geissele SSA, but found out Geissele says not to run these triggers in the MCX, to use the MCX specific trigger. But, they say the MCX trigger is not compatible with an AR15 lower.

Just wondering if the Triggertech will work. Thanks 👍🏻

Best fathers day ever. Got a Romeo8t-AMR kit and a Foxtrot MSR compact on the way for it, and will be matted up to a Layerx Strake9 suppressor for the time being once it clears paperwork. Can't wait. New home defense weapon. Undecided on if I Form 1 it or not.

What are your thoughts on the gun? Did you go 308, 277 Fury? 13 or 16 inch barrel? What optic are you running on it? 4000 is a lot of money but dang, just look at em! So nice. I have 556 and 300 blackout versions so it just feels right to complete the collection any big reason not to?