public service announcement: Sig MCX Gen 3 announced

[Corse]

I’m seeing how the guns are going to hold up to an additional 20k psi.

[MadAngler1]

Supposedly at 4 dollars a pop.

This is what I have seen for True Velocity hybrid case rounds. $3-4 a round.

Can someone tell me how the Sig MCX Spear in .277 Fury is superior to an updated SCAR-H with a NRCH in 7.62 NATO or a HK 417 with a lightweight chrome lined barrel or a DD/LMT AR-10 variant? Consider:

1. Barrel life
2. Cost of ammo for training
3. Bolt life, extractor life, small parts life
4. Life of system when running suppressed long term (stresses go up not down)

I think the original 6.8 SPC/6.5 Grendel push made sense. This .277 Fury/6.8x51 hybrid cartridge will only make sense to me when the above bullet points are at parity with current AR-10 platforms in terms of costs.

We are in a financial crisis. We need to stick to the basics.

[Corse]

This is what I have seen for True Velocity hybrid case rounds. $3-4 a round.

Can someone tell me how the Sig MCX Spear in .277 Fury is superior to an updated SCAR-H with a NRCH in 7.62 NATO or a HK 417 with a lightweight chrome lined barrel or a DD/LMT AR-10 variant? Consider:

1. Barrel life
2. Cost of ammo for training
3. Bolt life, extractor life, small parts life
4. Life of system when running suppressed long term (stresses go up not down)

I think the original 6.8 SPC/6.5 Grendel push made sense. This .277 Fury/6.8x51 hybrid cartridge will only make sense to me when the above bullet points are at parity with current AR-10 platforms in terms of costs.

We are in a financial crisis. We need to stick to the basics.

What optic would survive on a SCAR firing an 80k psi round? Would the SCAR survive?

[MadAngler1]

What optic would survive on a SCAR firing an 80k psi round? Would the SCAR survive?

I’m comparing known 7.62 NATO platforms to the 6.8 MCX Spear looking at total costs, parts life, service life etc.

I am not talking about rechambering a SCAR or AR-10 to fire 6.8x51.

[Labayu]

I’m comparing known 7.62 NATO platforms to the 6.8 MCX Spear looking at total costs, parts life, service life etc.

I am not talking about rechambering a SCAR or AR-10 to fire 6.8x51.

But you could totally rechamber a SCAR to run this caliber. It's got more bolt mass and a larger piston/gas block than the SPEAR right out of the box

SCARs are already overengineered to the point that they have 200k Rec/BCG lifespans with standard pressure 7.62x51. SCAR has a heavier bolt group but is still a lighter gun than the SPEAR with both running 13" barrels. Ditch the SCAR's 2004 quad rails and mill some M-LOK slots and be done with it.


I spent the big money on Swiss SIG 55x variants 20-30yrs ago and then more recently tried my luck with US SIG version and was sorely disappointed with their MIM parts, inconsistent heat treatment, out of spec assemblies and got the worst support from an arms manufacturer I've ever experienced. I don't think I'll ever trust a US made SIG no matter how many video game kids and SF fanboys get nocturnal emissions over it.

[MadAngler1]

What optic would survive on a SCAR firing an 80k psi round? Would the SCAR survive?

That wasn’t my point. I was just pointing out that there are other platforms that fire the 6.5 Creedmoor or 7.62 NATO round already in existence. I express concerns and doubts related to durability, longevity and costs of the .277 Fury Sig MCX Spear platform against other alternatives.

The new SCAR NRCH has a lighter bolt carrier, and supposedly a decreased impulse on the shooter’s shoulder and optics. Your concerns are valid, but I would suspect it could be worked out with further development and testing of the SCAR platform. A hydraulic buffer like B&T’s would really turn the SCAR into an even smoother shooting rifle (and I find mine to be quite smooth to begin with).

[MadAngler1]

But you could totally rechamber a SCAR to run this caliber. It's got more bolt mass and a larger piston/gas block than the SPEAR right out of the box

SCARs are already overengineered to the point that they have 200k Rec/BCG lifespans with standard pressure 7.62x51. SCAR has a heavier bolt group but is still a lighter gun than the SPEAR with both running 13" barrels. Ditch the SCAR's 2004 quad rails and mill some M-LOK slots and be done with it.


I spent the big money on Swiss SIG 55x variants 20-30yrs ago and then more recently tried my luck with US SIG version and was sorely disappointed with their MIM parts, inconsistent heat treatment, out of spec assemblies and got the worst support from an arms manufacturer I've ever experienced. I don't think I'll ever trust a US made SIG no matter how many video game kids and SF fanboys get nocturnal emissions over it.

Agree with your point about a SCAR chambered in .277 Fury. FN screwed the pooch though on their Mk20 rifles by not using an appropriately sized firing pin and firing pin channel on the 6.5 Creedmoor guns. Overall, the platform is well suited for higher pressure ammo assuming FN can improve the static buffer or install a hydraulic buffer.

I would also argue that 6.5 Creedmoor and 7.62 NATO with better designed bullets may provide adequate performance (not superior) to .277 Fury at a lower cost. Again, it bugs me that we are given zero data points regarding barrel life, wear on bolts and extractors from shooting a supposedly 80k+ psi round. 6.5 Creedmoor is a great round with far better commercial support than .277 Fury and other 6 mm cartridges, but we know very well that those good bolt gun barrels have a shorter barrel life compared to .308. Food for thought if the intent is to field what is essentially a modern battle rifle en masse to front line troops. We are facing a fiscal/budget crisis on the federal level. Now is not the time to field an unproven caliber. Hopefully my concerns don’t become issues that affect our troops.

I agree with you that I don’t trust anything Sig USA at this point because of their track record, especially with the MCX platform. Again, I would like to see how the .277 Fury Sig Spear would compare to AR-10 offerings (DD, kac, LMT), HK 417 and NRCH SCAR 17 chambered in 7.62 NATO or 6.5 Creedmoor. Such a test would be to see things like barrel life, bolt life, shootability, weight, ease of use, durability and all around performance. I venture to predict that portions of my hypotheses would be true. Namely, you could get most of the benefits of current AR-10 platforms in either 7.62 NATO or 6.5 Creedmoor compared to the MCX in .277 Fury at a lower cost.

Now the other issue is the wisdom of replacing the M4/M16 with the Sig MCX Spear. I would love to hear opinions from SOF, Marines and Army guys on this. Almost everyone I’ve met who served the past 20-30 years always emphasize the need to make platforms lighter, not heavier. Rarely did they ever complain to me about lethality of 5.56 NATO, especially if Mk262 was used.

[MadAngler1]

https://www.defense.gov/Multimedia/V...VideoPlayer581

Video from Pentagon answering questions about the two platforms. Nothing was asked about barrel life. To me, I think this was more about the new “light machine gun” and the fire control system that will be made by Vortex.

Let’s keep our fingers crossed and see what happens.

[1168]

Now the other issue is the wisdom of replacing the M4/M16 with the Sig MCX Spear. I would love to hear opinions from SOF, Marines and Army guys on this. Almost everyone I’ve met who served the past 20-30 years always emphasize the need to make platforms lighter, not heavier. Rarely did they ever complain to me about lethality of 5.56 NATO, especially if Mk262 was used.

A longish read:
https://taskernetwork.com/2022/04/24/layman-liason-xm5/
Skip down near the end to see SGM Pressburg’s opinion. My own opinion is very close to his, and I also have experience to put behind my opinion on the subject.

[VIP3R 237]

A longish read:
https://taskernetwork.com/2022/04/24/layman-liason-xm5/
Skip down near the end to see SGM Pressburg’s opinion. My own opinion is very close to his, and I also have experience to put behind my opinion on the subject.

Fantastic article that made me appreciate the need for something new with the overmatch argument.