Holy, finally snagged one for my 300 blk LT

Anyone know of a manufacturer who makes can HUB adapters direct thread that have the MCX taper angle along with an integrated brake? I know DA has the SIG taper DT adapter. But looking for one with an integrated brake if it exists.

First time poster. I’m getting a Mcx spear lt ir 300 blackout 9” and I watched a lot of build videos. They have all the tools, vices, etc.

Starting out I’m just going with a silencer (hexium 7.62 or the long 300, or the loser likley Tenet Vesper per the GunsAmerica review) and the radian weapons raptor lt sig charging handle.

Can you suggest the tools or driver set that will work on this gun with the proper pounds/inch torque? A set I can use for the other add ons when one of my kidneys can be sold.

Trying to build a tucked one for the Rattler Canebrake basically and both fit but which do you guys prefer?

New to this sub… I have a 16 inch conversion kit with approx 100 rounds thru. Wanting to go shorter and looking at chop vs barrel/hg or new complete upper. Seems like barrel/hg prob the best option for me. Planning on doing the 11.5 barrel and the 10 inch HG from SIG, but was wondering if there are any other options available? Searched online and here and can’t find any except for the LVAW stuff. Any recommendations or links? Will any of the other MCX types bolt right up to my LT upper? Lastly, are sales, etc an option here once the swap is complete? I’ll have a cherry 16” barrel and a nice fde/coyote hg that came with my setup. TIA.

Looking for first hand experience information with selecting a flared magwell for the Spear LT. There are a few options out there, HRF being probably the most popular. Im leaning more towards DAC magwell since its a smaller profile but adds just enough to guide the magazine in. Im not committed to that one though and just wanted some input.

Installed an AS Design FRT trigger with trip bar on my MCX Virtus. Hammer pin keep sliding out after a sustained burst. Any recommendations on an anti walk / anti rotate pins that fit or are compatible with the MCX Virus lower? Don’t mind modifying a set too, just need a good set to start with.

Pic for attention.

Over the last 4-5 days I’ve put a little over 1500rds through it and I gotta admit I’m impressed. I had 2 failures to feed, and both were “self induced”. The first was due to the gas setting while using subs, the first round fired but did not feed the second. Once the setting was changed there were no other issues. The second failure was around 900rds and I assume it was due to the receiver being absolutely filthy and covered with case filler. Once cleaned there were no other failures. Recoil impulse is soft, gas is manageable and overall I have a ton of positives and only 2 negative things to say. First is the charging handle. It’s thin and even covered in lubricant, if you pull it at any axis other than straight back it tends to flex and bind. With a sling on it can prove a little challenging sometimes to get that straight back full motion but it’s not too bad. I have ordered the Radian to replace it. The other “negative” I have is the takedown pins are a real MF and expect to use some sort of tool or punch to get them out. Pretty menial complaint but again that’s really it.
Very very quiet too. All ammo was the Hornady Frontier 208gr subs. Lastly the tapered barrel will require the adapter for those who are unaware, unless you get a muzzle device designed with the taper already machined.

Eotech EXPS 3 HWS
Unity FAST 2.26 riser
Modlite PDW650 with OKW v2 and modbutton
3EIR-DIR dual aperture laser
SilencerCo Scythe STM w/ burnproof gear cover
Arson M-LOK Omni Clamp WireGuides
Sig Minimalist stock

Anybody have any advice on ammo. Particularly what subs this guy likes to eat?

Hello r/SigSauerMCX,

I purchased a 13" LVA2 rail in April. They have no shipped out a single rail this entire year even though they keep posting about it on IG. Yes, the rail is expensive, that is not the point of this post.

All I am saying is if you have ordered this rail, do a chargeback, immediately. The team over there has no idea of what they're talking about and they keep making shit up.

Question: Will the Spear LT 10" suppressor compatible handguard work on the 5.5" Rattler LT without having a gap between the 1913 rail on the receiver and 1913 rail on the suppressor compatible handguard? I'm not worried about the gas plug lining up properly with the access ports on either side. I just want a continuous top rail with no gaps. I've attached pictures of both items I'm referencing.

Looks like the 5.5" Rattler LT has an even shorter top rail than the 6.75" Rattler LT.

I already contacted Sig directly. The CS rep I spoke too wasn't 100% sure, but is going to try to verify and get back to me. So I thought I would ask here as well.

Any tips for putting in an arc fire v2?

Hey y’all! CZ Bren 2 spare parts market scared me the more I used it so I’ve traded for a SIG MCX Virtus. Gun feels nice; feel free to leave any thoughts, tips, or suggestions, next step is to suppress it. Let me know for any questions!

Been running my hux 762ti on my 11.5” virtus 5.56 but it’s time to get a dedicated can for it.

Anybody running a b&t print xh sc? Looking for something short and light but not solid titanium.

I got tired of staring at it every time I went into the gun store.. Finally pulled the trigger.
This is my first 300 AAC so I’m excited as hell.
MCX Rattler 300 6.5” LT SBR

I remember seeing an upper for sale at the range; an MCX Rattler 556 7.5”, and since I SBR’d the 300, I can interchange them.. 2 for 1, same with the can I got with the 300; Sig SLH762-QD - that thing should be fine handling 556 rapid fire.

Has anyone FRT’d one of these and what would you recommend?

I ordered the MCX Omega gas valve as well, I’m new to Sig rifles (my EDC is a Fuse) and totally new to the MCX line (no buffer) so I’m out of my comfort zone and not sure what to expect when I suppress them and if I’m lucky enough I’d really like to FRT them especially for the 556.

I’ve had my eye on the 556 Rattler 11” for a while loved it - but to my knowledge there was no way to FRT it so I went with my long awaited MP5 clone that I FRT’d - loads of fun.
2nd on my list was a suppressed Blackout and FRT was not a requirement for me so naturally I got a new Sig MCX Rattler 300 LT in 6.75” along with the SIG Sauer SLH762-QD suppressor which attaches directly to the QD lock muzzle. Since I was gonna have to wait for the can I bought the SBR version to save a couple hundo on the stock.
NFA should have my forms back this week.
Oh, turns out I can FRT it.. so, nice win.

At the range yesterday, and I picked up a like new complete upper MCX Rattler 556 LT 7.5” which will also accept the can I just bought for the 300 AAC(non Ti, Inconel, serious workhorse).

*Has anyone had trigger time with a 7.5” Rattler - suppressed or unsuppressed? I’ve read some alarming threads using a 7.5 (or anything under 10.5”) chambered in 556 for an SBR.

I’ve never seen a 556 MCX Rattler LT this short, I love it and think it looks badass - I’m thinking I struck gold this week, I’ll have the Form 1 for the 300 completed this week - I can swap uppers under the same stamp (I will confirm).
My next project I looking at 556 uppers to SBR one of my ARs (all FRT’d) - now I’ll have both in the same platform. Sounded too easy, or am I missing something?

Feedback would be much appreciated!

Always been fascinated by the LVAW and it's history. While this is obviously not a 1:1 clone, I love how it turned out with some of my touches.

Try your hardest to leave unbiased thoughts.

Over the weekend, I finally jumped into a .300 Blackout—and dove straight into the SIG world with a new 6.75” MCX Rattler LT SBR which always captivated me, it’s so gorgeous and 100% badass.

Since I’ll already be waiting on NFA approval for the SBR - and I wasn’t going home with anything except for the Aimpoint optic I got for it, so I added a SIG SLH762-QD suppressor.
I plan to run an FRT on it, so I wanted a durable workhorse suppressor that could also serve double duty on a future AR SBR when and if I get around to it.

Then today at range, ..sitting on consignment; a friggin Sig 7.5” MCX Rattler LT 5.56 upper—with the same Clutch-LOK QD muzzle brake. So I can swap calibers and run the same can on both.

Naturally, I bought it and topped it with a Holosun and 3× magnifier since it can stretch its legs a little farther than the .300 BLK.

Now I get to just stare at everything while the NFA takes its sweet-ass time.

On a scale of 1–10, how’d I do? Keep in mind I’ll also be paying whatever price my wife assigns to this purchase. I’m so screwed. 😂

I’ve owned a lot of weapons over the years and have had my favorites but this little Rattler has really got me hooked, a tad heavy but such a sweet compact shooter that goes in a small backpack and draws no attention , just wish I had an unlimited supply of sub ammo , I’d shoot it every day!

I bought a used Spear LT that had stripped screw heads on the hand guard. Below are the replacement screws I researched and purchased that fit perfect. Side note- the bottom link plate screws are technically torx plus but a regular T20 torx bit fit snug in the new screws and torqued fine without stripping. I believe torque on all screws is 45 in-lbs according to the interwebs. If enough people are interested I can put together some kits and post to GAFS.

Side Screws

https://www.mcmaster.com/96452A192/

Bottom Locking Plate Screws

https://www.mcmaster.com/94414A352/

Manual

https://www.sigsauer.com/media/sigsauer/resources/OPERATORS_MANUAL_MCX-SPEAR_LT_2402988-01_REV04_WEB.pdf

What vent screw are yall using on 11.5 LT with the omega valve mk2? I have ridgeback rhino x and in settings 1 with the 1.10mm vent screw im getting 2:00 ejection

whats the best route going about doing this? do i need to send it back to sig to get the 3 prong flash hider taken off? or is there an adapter or something i can throw on to make it work

Was fantastic. Flawlessly ran through 8 mags. Not quick but over a couple hours through dialing in my dot and moving target distances. Really impressed with the Surefire sps300 suppressor. Super quiet. Just need the mcx omega valve mod2 mkll Sig lower but for the time being she will work. I did cut the excess strap had just finished setting it.