SIG M5 Spear Deep Dive: Is This a Good US Army Rifle?

Published 2022-06-03

Cool Forgotten Weapons merch!…

00:00 - Introduction
00:39 - TLDW
01:18 - NGSW history
04:11 - 6.8x51 / .277 SIG Fury cartridge
09:14 - Suppressor
12:53 - Rifle features and disassembly
23:42 - How it handles 80k psi
28:44 - Conclusions and rollout plans

The NGSW (Next Generation Squad Weapon) program began in 2017 to find a replacement for the M4, M249, and 5.56mm cartridge. It came to a conclusion in April 2022 with the formal acceptance of the SIG M5 rifle, M250 machine gun, Vortex M157 optic, and the 6.8x51mm cartridge. SIG released a handful of civilian semiauto M5 / Spear rifles and thanks to Illumin Arms I have one to examine.

The rifle (Spear is its commercial designation; M5 is the military one) is an evolution of the SIG MCX, which is in turn an evolution of the AR-15 and AR-18 systems. The MCX move the recoil spring assembly into the top of the upper receiver, allowing the use of a folding stock. It also has very easily swapped barrels and a suite of fully ambidextrous controls. Scaled up to AR-10 size and chambered for 6.8x51mm, the MCX became the Spear.

That new cartridge (commercial designated .277 SIG Fury) is designed to produce high muzzle velocities out of short barrel (the M5 has a 13 inch barrel).It does this by boosting the operating pressure up to an eye-watering 80,000psi, which required the development of hybrid case using a stainless steel case head. This allows the case to handle those pressures safely. The currently available commercial ammunition is loaded to lower pressure, however. Much of the military and civilian use of this rifle will be done with downloaded training ammunition, which uses a conventional all-brass case.

Both the M5 and M250 were ordered by the Army with suppressors on every weapon, a significant advancement in Army policy. The can is another SIG development, entirely made using additive manufacturing and designed specifically to prevent gas blowback into shooters' faces (which is succeeds at wonderfully).

Overall, I believe the M5 / Spear is an excellent rifle - soft shooting, reliable, and very accurate. However, that does not mean it is the right rifle for the Army. Will its ability to defeat modern body armor prove worth the tradeoff in extra soldier combat load weight and reduced ammunition capacity? Only time will tell...

Forgotten Weapons
6281 N. Oracle 36270
Tucson, AZ 85740

All Comments (21)
  • @wargriffin5
    US Army: "We've chosen a new service rifle for the future of modern combat."

    Ian: "Today on Forgotten Weapons..."
  • @kylecole7068
    Worth considering that we developed this weapon in anticipation of meeting Russian body armor, to later discover that Russians have never met Russian body armor.
  • They pushed that lightweight ammunition thing for nearly 20 years and in the end it didn't even matter. Imagine how frustrating that must have been for the competitors developing the polymer and ceaseless ammo systems for all that time. Looking at you Textron.
  • My favorite feature is the burned off finger prints on the suppressor. That's a great addition.
  • @JohnnyConroy
    As a 76 year old machine gunner with hindsight I LOVE this gun! A year as an Infantry Instructor at the Infantry School Weapons Committee, Machine gun Sub-committee and later a gunner in Nam with the M60, which I always loved. Others came and went, but I always wanted the 60. NOW I would like this gun... Christmas is coming up.
  • Next service rifle will have three charging handles, so there is absolutely no confusion.
  • @burtdanams4426
    This gun is seriously so beautiful. When you break it down and see how it all comes together under that shiny exterior, it just enhances my sense of awe
  • As a former infantryman, I would be concerned about the added weight, but I am also glad to see an anti-armor (body armor) capability. I do not like seeing the saw replaced with a mag-fed weapon though.
  • I believe the plan is to initially only field 20,000 rifles to gather long term maintenance and feedback data, and then produce an A1 and produce the rest in that model
  • @JKHYT
    I'm not a gun guy, I don't even own one. But your videos are so informative and thorough that I am captivated anyway. Great work.
  • @madmaxd1
    I love technological advances. This configuration definitely shows substantial improvements but I hope that they'll be able handle the huge undertaking of adopting new platforms with a new cartridge.
    In the past we've seen failures in platform adoption and also adoption of new cartridge individually by itself.
  • @CircaSriYak
    We’re all glossing over arguably the most shocking part of the rifle; no bayonet lug.
  • @Pyracantic
    It's the only dude I trust for weapon reviews and that is saying very little of how great this man is
  • @QuantumFerret
    Would love to see a video on True Velocity/Beretta’s NGSW submission. That was a much more interesting rifle, to me.
  • Suddenly the armies holding onto 7.62 rifles don't look so dumb any more. I know that their older guns with a big round don't equate to a brand new round and a rifle developed around it but it definitely seems like bigger rounds are coming back into fashion as more versatile.
  • Ian, I'd love to see a follow-up on this weapon updating us on any new developments/flaws. I've recently been hearing that the guns are having problems with jamming.
  • @johndaltrocanto
    Personally i find it at least somewhat suspicious that sig won both two huge army contracts, especially when they’re both so close to one another
  • @jbarbeau92
    It is disappointing that basically anyone we see shooting it and commenting on how soft shooting it is, isn’t shooting the full pressure ammunition
  • @jdjk7
    Hearing Ian make a comparison to a "gym bro who skips leg day every day" made me laugh a lot more than really made sense.