6mm SAW: What Should Have Been
Speaking of cartridges that were ahead of their time...
The 6x45 seems as if it would be a nearly ideal answer to the issues of 5.56x45 range and 7.62x51 weight.
That is interesting that they cut an M16A1 receiver in half, and elongated it to fit the 6mm SAW COAL. I did not know that. (from Johnny Carson) At 22.6lbs, the XM235 is too heavy, but it is interesting that it appears to be a bullpup with a rear box feed mechanism as described in the text. It also looks more SOPMOD ready than any other design I've seen so far. I wonder how the dual op-rod system works.
One thing I'll say about sheet metal military weapons, especially ones fired on full auto all the time, is that I have yet to see a stamped metal receiver that holds up to high-volume, whether it be the M60, AK, or SAW. All 3 of those designs see wear that creates tolerance stacks over the life of the receiver, until the system becomes a jam-o-matic.
In contrast, the MAG58/M240 is built as solid as a brick out house, and east live rounds all day long, year after year like it's fun. It has an extremely sturdy receiver, that mates exactly with the feed tray cover, forming a tight connection where there is not really any room for the system to operate outside of the reciprocating components' range of movement. It is truly a well-built system, but too heavy as a result.