06-10-2012, 05:47 AM
I think that to have one cartridge in two versions, differing only in the length of the bullet protrusion and the chamber pressure, would be confusing. We don't want to get into a 6.8mm Rem situation, with two different chambers!
If we're no longer limited to 5.56mm action lengths, then IMO it's better to produce a slightly different case, extending it a bit to make sure that it can still deliver the required performance from 20 inch barrels when loaded with lead-free bullets (especially the even longer tracer versions). That might also mean that it needn't be loaded to maximum pressure to start with, which is no bad thing.
Edit to add: a little extra capacity would also make it easier in due course to produce a polymer cased (with metal base) version, since these tend to have thicker walls. These cases are improving all the time, and offer big weight savings - important for the military.
If we're no longer limited to 5.56mm action lengths, then IMO it's better to produce a slightly different case, extending it a bit to make sure that it can still deliver the required performance from 20 inch barrels when loaded with lead-free bullets (especially the even longer tracer versions). That might also mean that it needn't be loaded to maximum pressure to start with, which is no bad thing.
Edit to add: a little extra capacity would also make it easier in due course to produce a polymer cased (with metal base) version, since these tend to have thicker walls. These cases are improving all the time, and offer big weight savings - important for the military.