Since 2020 the Covid-19 era it’s been all downhill so with that said, bought my 1st AR-15 platform a Sig M400 Tread and from then on I was hooked. Now I‘ve got somewhere between 15 and 20 AR15’s with a few AR10’s built by me and they’re just inter-changeable. If I break or damage my 300 blackout just take off what’s broken and mix and match with another upper or lower, how easy is that? Very freakin easy. 🤣🤪😝

 

I'm just going to touch on the MCX vs. DI gun. The rest of the **** stuff is just fantasy. So maybe let that drive your decision as it isn't really grounded in how things would be or even how bad they'd be. I've worked in areas of total societal breakdown as well as conflict zones so I have first-hand experience and all without having a weapon.

I have the MCX Spear LT in 300 blackout so it has a barrel that's almost twice as long as the Rattler. I think the higher performance of supers over subs is worth having a 3.5" longer barrel. IMO. I'd have no problem hunting out to 200 yards with a 110 or 125 grain supersonic, something like the Barnes Tac-TX projectile.

Vs. a DI gun, a well-built DI gun with quality parts is going to shoot a long time without malfunctions. The piston guns still get bolts really dirty, especially with subs. It's also possible to build a much lighter gun with a DI setup vs. the Sig. I had a 10.5" (as well as an 8.5" barrel) DI 300 blackout that was sub-5 pounds, nothing super exotic, where the LT is at least half a pound heavier. Feels like more. Doesn't sound like much but there's more weight out front on the Sig and the difference in feel between the two was pretty dramatic. The DI gun's weight was further back and better balanced. Most of the components were "normal" except for the buffer tube, BCG and hand guard which were all light weight. If I'd taken it a bit further, I could have gotten it down to 4 pounds naked.

In terms of felt recoil, the DI gun, hands down, is softer shooting with supers. Subs are about equal.

I don't notice less gas to the face with the Sig but I also use a flow-through suppressor (Huxwrx). The bolt still gets nasty. The rest of the BCG does remain cleaner but the bolt and barrel extension get just as dirty as a DI.

Where I think the Sig shines is that it's fairly bomb-proof. It just eats everything I throw at it without any FTF's whatsoever no matter the ammo I load up. In fact, I did a test with the problematic Hornady 190 grain sub-x rounds. I loaded an entire magazine with various headspace and bullet seating depths (all within spec, just different) and ran through the mag as quick as I could. Zero malfunctions, feed, cycle or eject. I trust it 100% with supers and subs of various brands and bullet weights.

The Sig worked out of the box although I did add the Arisaka hand guard brace thingy and switched over to a Geissele SSA trigger which is better than the Sig trigger (but still highly over hyped). The piston system is very robust but no idea on how long it'll function before needing cleaning or a rebuild. It cycles everything and admittedly, it's a bit over-gassed with supers. But again, it cycles every ammo I've ever thrown its way which is at least a dozen different brands, bullet weights, etc...

With a DI gun, you'll have to clean more often but any solvent will work and you could lube with motor oil. If you went with something like an RCA BCG, their coatings would necessitate less lubrication. Climate will obviously have an impact on all of that.

Accuracy wise, I think it's a toss-up with an edge to the DI gun. The Sig has a fast barrel twist rate which really necessitates solid projectiles for supers. It's not as much an issue in the Rattler as the bullet velocity is going to be considerably slower than with a 9" barrel. You'll never exceed the bullet's rpm limit. With the DI, you can use jacketed bullets which are easier to develop an accurate load with and can even go with plated subs for cheaper plinking rounds. Solids are very unforgiving in the reloading department plus they're ******* expensive in comparison.

If society ever truly broke down to the levels you're envisioning, and you actually manage to last more than three months, let alone a year, you'll want a bolt gun. Five years down the road, an auto loader will have likely failed already unless it's used very sparingly. Spare parts may be non-existent for whatever reason. In reality, it'll be whatever gun/ammo you come across while wandering, trying to survive and not the one you currently have in your gun safe.

All that said, out of all my rifles, the suppressed Sig is next to me when I go to sleep at night.

 

I have a Colt M4 DI and a MCX Patrol short stroke piston. When I go shooting I always grab the Sig. I cannot remember the last time I shot the Colt. I don’t really know why but the Sig just feels better to me. I really like the Piston design. There is no comparison to cleanliness after a day at the range. The Piston gun is way cleaner.

As for your decision on the Rattler. I bought mine about a year ago in 300 blk and it quickly became my favorite gun. I suppressed it with a Nomad 30 and I could shoot it all day long. The .300 blk suppressed is awesome. I haven’t done it yet but I’ve seen videos of it being accurate out to 200 yards which amazed me. The Rattler is perfectly sized for home defense a backpack or carrying in the truck. To me the Rattler is the perfect gun. I don’t think you would be disappointed if you got one. Here’s mine.

 

I also use a flow-through suppressor (Huxwrx)

I’ve got three and love them.

 

Dang! Three Rattlers? That is AWESOME!

 

Dang! Three Rattlers? That is AWESOME!

I wish brother, three Huxwrk silencer. 🤣🤣🤣

 

You have too much money. 😂

 

My go-to is a suppressed PWS upper over a homebrew receiver. A little more commonality with the DI AR platform than the MCX, but the whole gas system and bolt carrier is proprietary (I expect you could substitute a standard bolt if necessary though). Heavier than a DI gun (it's a long-stroke piston), but it's a better suppressor host.

I haven't had anything on it break, but I do expect that the piston is one of the more likely parts to fail under heavy use; it's pretty long, and while it feels sturdy, it is a 2-part piston and not that much thicker than a standard gas tube.

 

It’s a short stroke piston system according to Sig. The lower is completely compatible with Standard AR parts.

 

you may also want to consider comg dissent and Mike foxtrot. Both have no buffer tube. Dissent has more caliber and barrel options at attractive prices and mount to standard AR lower just like mcx.

my mcx is the first Gen. It is reliable but at a full length. Love it still but any type of **** I will resort to a pdw and probably lighter than a rattler. Go with a 9mm pdw and a side arm in same caliber unless you plan to engage at 100yd+ in a battle situation.

 

Is the arisaka zero retention device truly necessary? I have a magpul mbuis on the end, and never noticed a huge change.

you may also want to consider comg dissent and Mike foxtrot. Both have no buffer tube. Dissent has more caliber and barrel options at attractive prices and mount to standard AR lower just like mcx.

PSA Jakl is another option. Im building one in a month or so.

 

Thanks so much for all the input so far guys.... now here's a technical question:

Since, if I really do leave the AR platform behind for the MCX, common sense and my tendency to over-plan for contingencies dictates that I will need to buy a LOT of spare parts. Easily $1200 worth of spare parts to really feel secure in having a 30,000rd+ firearm. Here's something I"m confused about:

Obviously the MCX Bolt Carrier is proprietary... but is the BOLT? I have seen Bolts supposedly for the MCX Virtus, Rattler and all the "outgoing generation" of MCX models that looked definitely proprietary. I've seen Bolts for the new SPEAR and SPEAR LT that look like regular old AR Bolts. Is there a difference between the older MCX generations BOLT and the new SPEAR and SPEAR LT? Will regular old Milspec AR bolts work in either? Both?

I know the CARRIER for the RATTLER, VIRTUS etc is very different from the new SPEAR and SPEAR LT is very different.... and that's frustrating as hell, but that's SIG all over lol!

 

Good question. I'm curious to know the answer too.

 

Nobody?

 

The best way to buy spare parts IMO for MCXs is to to buy another MCX; its been less expensive than buying new barrels, carriers, uppers and lowers. There is a life time warranty for the entire new rifle.

If you buy the MCX stock adapter from SIG, you can build your own hybrid lowers from stripped AR lowers.

The only major spares I have for the MCXs I have are a complete carriage assembly for 5.56/300 and a hybrid lower. I bought the spring assembly for $200 on sale years ago, now they cost $350 plus tax.

Bill

PS: If I were getting into the MCX today from scratch, I'd go Spear LT 110%. B

 

My theory is if it super breaks, Now i get ab LT, If it breaks certain parts, they get upgraded to LT parts.

 

My theory is if it super breaks, Now i get ab LT, If it breaks certain parts, they get upgraded to LT parts.

Used MCXs in good shape are ok because the bolt carriage assembly of the LT and trigger related parts from the LT are all backward compatible. Things like extractors for 5.56 are probably the same across all generation; the one that will be different is 7.62x39R.

Bill

 

Test it out!

 

Testing MCXs is very dangerous to one's financial health! They are hard to let loose of.

Bill

 

I’ll take an AR platform over the MCX all day everyday in a rifle style or rifle ammo weapon.
I have way more options on an AR platform and accuracy is as good for less money. Also Mil Spec means no crazy changes that makes one part not compatible with the other.

 

I suspect, if you get a Galil Ace, you'll never need spare parts.
Worrying about anarchy is mostly a function of too much TV. Sure, there will be unusual outbreaks of violence like some of the ANTIFA, and Jan 6 insurrection, but home and family defense needs would be short-lived, and be handled with a combat load-out of 240 rds 77 gr 5.56, 3 mags of your favorite combat pistol ammo, and a box of 12 gauge you're comfortable with.
Stockpiling ammo and lots of black rifles -- yeah, I do it too but no fantasies of me against everyone else.
In my real world, the threat last night was a coyote 40 meters fromu the chicken coop. My go-to was a Tavor 5.56 w/ 1-4x scope. Of course, by the time I got it, Coyote had disappeared, Still, as we say here, Coyote waits....
Bottom Line: Trying to imagine the scenario where your MCX wears out in some 5,000 round anarchic firefight, so you get on your mobile, call Sig CS, give them the SN of your MCX and they overnight the parts to you.
Anarchy takes an intermission?

 

I suspect, if you get a Galil Ace, you'll never need spare parts.
Worrying about anarchy is mostly a function of too much TV. Sure, there will be unusual outbreaks of violence like some of the ANTIFA, and Jan 6 insurrection, but home and family defense needs would be short-lived, and be handled with a combat load-out of 240 rds 77 gr 5.56, 3 mags of your favorite combat pistol ammo, and a box of 12 gauge you're comfortable with.
Stockpiling ammo and lots of black rifles -- yeah, I do it too but no fantasies of me against everyone else.
In my real world, the threat last night was a coyote 40 meters fromu the chicken coop. My go-to was a Tavor 5.56 w/ 1-4x scope. Of course, by the time I got it, Coyote had disappeared, Still, as we say here, Coyote waits....
Bottom Line: Trying to imagine the scenario where your MCX wears out in some 5,000 round anarchic firefight, so you get on your mobile, call Sig CS, give them the SN of your MCX and they overnight the parts to you.
Anarchy takes an intermission?

On the other hand, an MCX would be cool.

 

I have never owned a DI AR15. My first one was home-built with a Superlative Arms piston kit. I loved it so much it was recently replaced with a PWS upper on a Radian lower. It runs suppressed well and I have never noticed any gas blow-back into my face. Outside of the PWS having a long-stroke piston, the MCX is a better platform because of the internal buffer system and quick-change barrel/handguards. I just picked up a JAKL which is awesome in 556 format but the barrel twist for 300-BO is not ideal for subs. That is why my next rifle will an MCX tacops.

 

I suspect, if you get a Galil Ace, you'll never need spare parts.
Worrying about anarchy is mostly a function of too much TV. Sure, there will be unusual outbreaks of violence like some of the ANTIFA, and Jan 6 insurrection, but home and family defense needs would be short-lived, and be handled with a combat load-out of 240 rds 77 gr 5.56, 3 mags of your favorite combat pistol ammo, and a box of 12 gauge you're comfortable with.
Stockpiling ammo and lots of black rifles -- yeah, I do it too but no fantasies of me against everyone else.
In my real world, the threat last night was a coyote 40 meters fromu the chicken coop. My go-to was a Tavor 5.56 w/ 1-4x scope. Of course, by the time I got it, Coyote had disappeared, Still, as we say here, Coyote waits....
Bottom Line: Trying to imagine the scenario where your MCX wears out in some 5,000 round anarchic firefight, so you get on your mobile, call Sig CS, give them the SN of your MCX and they overnight the parts to you.
Anarchy takes an intermission?

Anyone who talks like this definitely didn't live in Baltimore in 2015 when a couple thousand good citizens decided to burn, loot, smash, B&E and worse while city leadership told the police to STAND DOWN for a few days.

I did.

 

How many rounds did you fire? Was it a residential area?

 

The biggest problem and benefit with Sig is the same thing, their constant changes. On the one hand their frequent changes/updates/new stuff is nice and they market it well. The downside is you can almost consider Sig guns non-upgradeable. By this I mean there's at least 5 revisions of the MCX that are not backwards compatible in barrels, bolts, carriers, triggers, pistons/operating rods etc. and it's only what 7 years old, and if you can get parts to upgrade, the cost is so high you might as well just buy another gun. Now you can say the benefit of that is it frees Sig up from being restricted into only backwards compatible updates, and that's true. The downside is, those updates, should you want them, probably require buying an entire new gun. Even if you could buy parts from Sig, their prices are RIDICULOUS.

Worse yet is Sig's customer service most of the time doesn't know the pedigree of the changes/parts or what is compatible. I just went many rounds with Sig customer service on an old 2015 very very early MCX barrel to see if it would work on my Legacy MCX (it won't) I had to take a lot of pictures and make 3rd grade level drawings to get them to finally understand the issue. Had the same problem with the MPX's, often Sig's customer service sends out wrong generation parts, if they even have parts, and they make you return the whole gun for what should be insignificant parts replacements.

If I put any significant weight on being able to update/upgrade or get spare parts down the road with low hassle, I would avoid Sig's proprietary designs, or buy a spare gun up front, which means you're paying ridiculous prices twice. Meanwhile with just about any other AR platform, 5 years from now I'll bet you could easily replace every part in it, with something else quickly and easily and be back up and running, or updated/upgraded without hassle.

 

The biggest problem and benefit with Sig is the same thing, their constant changes. On the one hand their frequent changes/updates/new stuff is nice and they market it well. The downside is you can almost consider Sig guns non-upgradeable. By this I mean there's at least 5 revisions of the MCX that are not backwards compatible in barrels, bolts, carriers, triggers, pistons/operating rods etc. and it's only what 7 years old, and if you can get parts to upgrade, the cost is so high you might as well just buy another gun. Now you can say the benefit of that is it frees Sig up from being restricted into only backwards compatible updates, and that's true. The downside is, those updates, should you want them, probably require buying an entire new gun. Even if you could buy parts from Sig, their prices are RIDICULOUS.

Worse yet is Sig's customer service most of the time doesn't know the pedigree of the changes/parts or what is compatible. I just went many rounds with Sig customer service on an old 2015 very very early MCX barrel to see if it would work on my Legacy MCX (it won't) I had to take a lot of pictures and make 3rd grade level drawings to get them to finally understand the issue. Had the same problem with the MPX's, often Sig's customer service sends out wrong generation parts, if they even have parts, and they make you return the whole gun for what should be insignificant parts replacements.

If I put any significant weight on being able to update/upgrade or get spare parts down the road with low hassle, I would avoid Sig's proprietary designs, or buy a spare gun up front, which means you're paying ridiculous prices twice. Meanwhile with just about any other AR platform, 5 years from now I'll bet you could easily replace every part in it, with something else quickly and easily and be back up and running, or updated/upgraded without hassle.

I too have a very very early MCX. I'm curious about the barrel differences. The only differences that I've noticed from my other legacy MCX are all in the lower. I've replaced the flat recoil pad with the newer recoil pad that works better with the newer BCG.

What'is different about the barrel?

Bill

 

So there were some very early MCX's in 2015, from what I understand they were sold through Cabelas, maybe other places as kits. They only are compatible with the pre-recall bolt/carrier group, this is because each barrel in the kit came with it's own silver operating rod, and it had to be installed on the bolt/carrier when the barrel/caliber was changed. Those operating rods are not compatible with post-recall bolt/carriers. Another telling feature of these is they had a self-adjusting gas block instead of the 2 position version.

As such the post-recall MCX's, even other early legacies their operating rod will not engage with these barrels (too short) and you can't simply swap the piston rods because they are different diameters/lengths and head designs. I have 3-4 legacy MCX barrels/lengths and none of them could be swapped to provide the right combination.

MCX Piston Assembly Question.

Do you recall any of the legacy MCX barrels coming with this piston assembly? I bought this barrel for my Gen 2 (non-Virtus, but post-recall legacy parts) MCX and it is not providing enough gas to drive the bolt carrier back to eject the spent cartridge and feed the next round. It doesn't appear...

www.sigtalk.com

When I talked to Sig about the issues I was having, they really could not understand the problem, and evidently had no knowledge of these early versions. They kept getting hung up thinking I was trying to put a Virtus barrel on a Legacy and were fixated on if I had a tapered bolt or not. It took quite a few diagrams/photos etc. to get them to understand. My hope was that Sig had a piston rod/gas setup that could swap in and work with the post-recall carrier or they would replace the barrel because as it is now it can only be used on pre-recall bolt/carriers, and I didn't want to run a pre-recall setup, you'd think with a recall Sig also would not want people trying to run pre-recall setups. Sig was not interested in that and only said that if I wanted to I could send my gun in with the barrel and they would see if they could make it work, but it would likely cost significantly more than just buying a new barrel/bolt. The whole reason I took a chance on this barrel was that the stock 16" barrel on my MCX shoots very poor, especially with lighter 223 rounds as so many have run into with the MCX's. Like 6" at 50yds poor, but Sig felt that was fine since it did better with heavier rounds and blamed it on 1:7 twist barrel, even though I have other 1:7 barrels from JP etc. and they have no issues with 55/62gr rounds. Heavier match bullets were 2-3 MOA at 100, meanwhile a JP barrel runs them close to MOA. It's honestly left quite a bad taste in my mouth because to me any 5.56 non-precision AR, should run 55/62gr ammo with reasonable accuracy, it's a cop out to say you need to run 70gr match ammo to do better than 6" at 100yds.

 

Thanks for the reply. I had forgotten the Cabellas version of the MCX.

Bill

 

As mentioned Sig changes parts way too fast. The reason is they bring guns that aren't ready to market. They don't care, we pay for it.

I own a rattler but A mil spec AR is best option IMO, thats why I have a few of them.

 

Get a Galil for the oy vey factor.

 

Get a Galil for the oy vey factor.

I've tried a number of different "AK-Related" rifles and pistols over the years and I just can't get a feel for them. What can I say? I just plain old don't dig em.

Although..... I will admit to being attracted from time to time.... like after watching THIS:

https://www.youtube.com/watch?v=ayGwuyfgUhk

(...... man, talk about recoil control! Sheesh..... and no, it's not a select-fire, he's just doing that.... with his finger.)

 

Ya know sometimes with threads like this, I will often leave them alone for long periods of time and then come back. Generally speaking one of three things will have happened in my absence:

1. It just dies right away
2. It degenerates into heated, obscenity-laced and often downright hateful arguments over the proper torque to apply to a 30mm mount or some such equally trivial thing.
3. A consensus (if there is one) on the issue that is of most concern to most people will organically manifest itself from the number and frequency of posts related to that issue.... often in striking contrast to what people come right out and say is the issue they're most concerned with.

Luckily, we have a #3 here, or at least a half a one.... and it's clear the issue that most people would consider a roadblock to replacing one's AR assortment to an all MCX assortment is a TIE between parts cost & availability and frequent factory redesigns which make backward-compatibility at best an unknown.

Right now I own a Geissele Super Duty 11.5" in 5.56 and a Sig Rattler in .300blk. If I'm gonna be perfectly honest (and some of y'all are gonna make sure I regret it, watch). I don't really want BOTH an MCX and an AR. I want both calibers but in a common platform. My reasons are my reasons and they're difficult to justify, so I won't even try. Nevertheless, I need to decide whether to sell the Rattler and get .300blk AR, or sell the AR and get a Sig MCX SPEAR LT.

I'll say straight up that I prefer shooting the MCX. It's shorter, all the weight is either at or behind my support hand (left hand) and the recoil impulse is different in a way I find more manageable and even pleasant. I certainly don't miss that heavy spring THWAK-TWANG'ing directly under my ear and jaw. Despite lacking certain "hi-end" and ostensibly "hard use" appointments such as a chrome-lined bolt carrier and barrel, most people seem to say that the Sig stuff is going to be the tougher unit.... who knows if that's true, it seems counterintuitive to me but I will say the MCX stuff I've owned and used definitely seems more tank-like than any AR I've had experience with, at the expense of weight, of course. My Rattler gives me the impression I could toss it down a long flight of concrete steps and it will still be in perfect order... I would NEVER do this with a DD or Geissele.

Obviously, not all these MCX benefits would carry over to a longer-barreled 5.56 Spear LT; the weight would be the first thing I'd get sick of, after getting over the pain of dropping another thousand dollars to upgrade from my Super Duty to the Spear LT. And then come the parts considerations discussed above... but here's the thing;

With the military adoption of the Spear and Spear LT, and shortly to be literally MILLIONS and MILLIONS of these things out there in the world, does it not seem likely that both Sig and, moreover, the aftermarket, will respond in much the same way as with the P320 ...... and just a few years from now you'll be able to choose between dozens of readily available complete bolt carriers and piston/barrel assemblies and stripped lowers from different companies... some even being an improvement over the factory part?

This is not to say the MCX is ever really going to replace the AR platform in the commercial market, or at least not for decades, but from a plain business & economics standpoint, would it not seem in the best interest of many, many companies (and many more NEW companies still to come) to begin offering MCX parts and upgrades just as soon as they can possibly do so?

If any of that is true, then really WEIGHT and short-term cost are the only things holding up a decision in favor of the MCX.... and long-term costs would soon balance out and even be in the MCX's favor if greater/longer reliability versus AR's turns out to be a fact and not simply marketing....

Your thoughts?