Sig MCX Spear vs. MCX Spear LT

[PNorris]

The SPEAR has been commercially available for over a year now: https://www.sigsauer.com/spear.html. They sold a limited edition kit in .277 Fury as a factory SBR and with a can during a first run: https://www.sigsauer.com/blog/now-sh...cx-spear-rifle

As a large frame system, why would they ever offer it in 5.56×45mm? There's the hope that it'll be available for 7.62×51mm and 6.5 CM, but small frame calibers seem like it'd be extremely niche and probably institutional only (like the retrofit kits for the SCAR 17).

I saw that. Just curious why they did not update the system the 5.56 uses. Also, I searched for the Spear online and only found the LT. Let me correct that. I just found the spear, however, 7k . . ouch!

[1168]

I have been trying to find information on the web, as it appears that the Operating systems are very different. The MCX Spear appears to use an AK style long stroke piston design, whereas the LT appears to use an AR 18 type system. Only the LT appears on Sig's website. I prefer the AK style system and I was curious if this going to offered to the public. If so, I wonder if only with their new hyped up cartridge and not the 5.56.

(SNIP)

Thoughts or anyone with knowledge?

They are both short-stroke; neither operate like an AK.

I don’t think the large-frame gun will be offered in 5.56.

[constructor]

PNorris,
Here is your first post quoted-"I have been trying to find information on the web, as it appears that the Operating systems are very different. The MCX Spear appears to use an AK style long stroke piston design, whereas the LT appears to use an AR 18 type system. Only the LT appears on Sig's website. I prefer the AK style system and I was curious if this going to offered to the public.

The Sig Spear does still not have a AK type long stroke operating system. BOTH the Spear and Spear LT have short stroke operating systems. Maybe you should have said I like the one with the single big spring and rod.

[PNorris]

I was fooled by the bolt carrier group of the MCX Spear, as it almost appears that the piston is attached to the bolt carrier group like an AK, or even like the PWS bolt carrier group. (aka long stroke piston) There obviously must be a small piston in the housing on the barrel that strikes that long rod. (like the MCK Spear LT) I would call it an op-rod for lack of a better term. Since I could not see any detailed photos I thought that the rod was the piston and that it sealed inside of that housing without a piston being in there. I stand corrected. Still, I remain curious since this is the newer design why they simply did not make a smaller variant for the MCX Spear LT. Most likely cost I assume.