This is truly one of the darkest days for US small arms , True Velocity’s polymer case was a huge step forward , innovative but not aggressive ,can be used on other munitions , less powder with same power, overall controllable ,and they just ditched it
Not really. First the cartridge design is still being looked at for use in other weapons .50 BMG by the marines and .338 Norma for socom. So it’s not the end of the polymer cased ammo for TV.
Next the 6.8x51mm TVCM was designed for the RM277 Bullpup. To get its pressure and velocity it had to have a full length 19-24” barrel. To keep that in the Army’s length requirements demanded the Bullpup design. Now Bullpups aren’t terrible but aren’t great either. They pay for what they are. To get maximum barrel length in as small possible they often trade off ergonomics. The army wants not just to be able to shoot the rifle but have the full use of the rifle. The XM5 has similar length and ergonomics to the M4 which is probably the most ergonomic battle rifle on the market. Plus the folding stock means it’s actually able to be shorter than M4 useful for a mech army.
Farther I would argue that TV whom has no real experience as a small arms manufacturer blew all its limited experience in making the rifle but phoned in the automatic weapon. Which is ironic as it seems likely that the operating system was derived from the formerly GDLS now Lonestar future weapons (part of True velocity) LMMG. Although interesting the mechanism behind the RM277 and LMMG was a bit of a Rube Goldberg machine. You have a short stroke piston attached to a long recoil action. This complicated maintenance and would likely comprise reliability.
Where the LMMG used a belt feed the RM277 went with a 20 round box magazine. This comprise did the same thing the British did with L86A1 and Norinco did with QBB95. They took their Bullpup rifle slapped a bipod on it and a longer barrel. As an automatic weapon it trades off a lot especially since the army was already trading off 10 rounds per magazine to get this.
Sig brought a proper LMG to the party. Where some may try and argue controllably this far Sig’s offerings seem to have that. As if they were otherwise then they wouldn’t have passed field trials.
Father although TV has demonstrated rechambering its ammo into M240 and M134 their is no actual evidence that the same cannot happen with their ammo. If anything I suspect TV was trying to prove that they could to try and make up for the short comings of their IAR.
Finally their is manufacturing base. TV via Lone Star Future weapons might as well be a couple guys in a garage. Now yes that’s how Microsoft was launched but only with substantial existing business investment. Frankly to meet a near future weapons program they don’t have it. Sig does.
Sig probably also got a huge bonus point set because they control everything on the product via their licensing. TV had to team and negotiate cuts for the suppressor manufacture and partner with Beretta for manufacturing assistance. Meaning that if the team can’t meet army demand, they have to negotiate to expand production beyond the initial builders. Sig by having it all in house allows the army the ability to take the licensing if Sig can’t meet demand and offer additional contracts to other vendors. IE if sig couldn’t match demand in time of war the DOD could go to say FN and have them make additional batches. That was a major aspect that lead to Sig’s M17/M18 wins.