Long story short:

4 complete Colt 6920s had the LE lowers sold to collectors, lowers were replaced with SOLGW and one Geissele lower, all with A5 kits, stock springs and A5-2 buffers.

Several malfunctions observed, all incomplete fail to feeds when charged with the handle or from an open bolt using the bolt release.

These rifles, mags, ammo, and lube have all been extensively vetted with the carbine/H2 Colt lowers and reliable for years, there is no issue with the uppers. There is no issue with the lowers, they have inspected and everything is as it should be.

Sprinco springs won’t be considered as corrosion has been an issue in the past with those (saltwater/air environment).

Tubbs flatwire springs are about all I’m considering at the moment because they’re stainless and I like the idea of more coils (why I liked the A5 too).