A Brief Overview of the Evolution of the Sig Spear M7 - "M7 PIE" AUSA2025 Coverage

Heval
Oct 16
4 min read

While historical Soviet and Rusfed content is Safar's specialty, I recently had the pleasure of attending AUSA2025 to check out a sliver of the future. That includes the new M7 PIE (Product Improvement Effort). But first, how about we start at the beginning of the Sig Spear's journey. Then, we will take a look at the M7 PIE with hands-on photos.

Most of the following will be thanks to Soldiersystems:

MCX-MR - 2015

The Spear's first iteration was in 2015 as the MCX-MR (Medium-Range). This was Sig Sauer's submission to the Compact Semi-Automatic Sniper System (CSASS), and was a 7.62x51 gun with obvious inspirations from the regular intermediate caliber MCX line. While most of the Sig Spear was already there, especially internals, numerous geometry changes are noticeable in about everything, and features were omitted, such as the ambi bolt release.

The handguard remained key-mod and still resembled the smaller MCX's handguards. The layout of a long barrel and the adjustable stock was, of course, to match the Squad DMR requirements of the CSASS program. HK's HK417 would ultimately end up beating it in the program and was adopted as the M110A1.

Proto-Spear AUSA 18

At AUSA 18, during the warm-up of the Next Generation Squad Weapon program, SIG showed an example of the MCX-MR in a more "battle-rifle"-esque configuration with a regular MCX stock, shorter barrel, and still key-mod handguard.

Sig Spear - 2019

In 2019, the Spear would become much closer to what we see today, with a now M-LOK handguard and ambidextrous bolt release.

XM-5/XM-7 - early 2020s

13.5" XM7 with the NGSW program XM157 "smart" optic. Image credit: US Army

The most seen version of the rifle during testing and selection in the NGSW program featured more changes to the handguard, a steel insert for the brass deflector, and an AR-style Magpul stock. It would receive the XM5 designation to succeed the M4 designation. However, it was changed to "XM7" later on in order not to be conflated with one of Colt's offerings, sold under "M5" as the product name.

XM7/M7 2023-onwards

XM7 with the included canted backup iron sights. Where the forward assist was in the forging can still be seen on this example. Note also the handguard's new profile. Image credit: US Army

XM7 with an upper using an updated forging, with no traces of the forward assist left. Image credit: US Army

After SIG's selection, the rifle would be further tweaked with the omission of the forward assist. They are generally not needed on AR-10-esque rifles because of the increased weight of the bolt carrier group. The handguard also saw another update to improve its rigidity. Sometime after this, the designation would become simply "M7" as SIG has, at the time of writing, now delivered 30,000 rifles to the Army.

M7 PIE and M7 Rattler PIE - AUSA2025 Hands-On

10" M7 "Rattler" PIE carbine. Photo by author.

One of the biggest and most serious detractions, especially in the Trent report, of the NGSW program and the selected SIG Spear was and is its weight. Sig has responded to that concern with the "Product Improvement Effort" or "M7 Enhanced" versions. Firstly, it's now offered in 11.3" and 10" configurations at 7.6 lbs and 7.3 lbs respectively, compared to the previous 13.5" M7 at 8.4 lbs. Those weights are without attachments and unloaded.

A shorter and lighter suppressor was also developed. It now includes a heat guard to prevent it from burning clothes and reduce its thermal signature. The heat shield is a metal sintered part connected to the body of the suppressor by numerous small supports at the ends. I believe it will perform much better than the reportedly poor-performing heat guard they included with the MCX SURG.

I personally found the rifles, again without attachments, to be decently balanced in hand. Many other small changes were made to find weight savings, including shortening of the oprod, the side-charging handle, plus the brass deflector now being polymer, geometry changes of the upper, removal of the folding mechanism of the stock, and slight changes to the barrel profile; photos below.

It's yet to be seen how much these PIE versions of the M7 will be delivered to US troops, as the order and procurement are already going strong for the previous variant. This also doesn't resolve all of the concerns about the M7, however, such as its lower capacity and considerable recoil impulse, i.e., its ability to output fire superiority, alongside worries about the XM157 optic's reliability.