6mm Grendel Group Design Project

[stanc]

Solid reasoning, Stan, can't fault it. But none of us knows conclusively if the change was due to technical merits or politics or hidebound thinking. All of which, to me, are distinct possibilities.

I agree, John. Those are all possibilities. Some years ago I tried to find out for sure, and asked Frank Hackley (Frankford Arsenal's last commander) about it. Unfortunately, even he did not know the reason they decided to go with a 20-degree shoulder, since it happened long before his time there.

However, I have to give them the benefit of the doubt. The developers clearly were progressive in their early thinking on shoulder angle, because they did just as you advocate and opted for 30 degrees instead of a more conservative angle. Plus, there is other evidence to support the idea that the shoulder angle changed as a result of reliability testing -- neck length also increased, a year or two before the change in shoulder angle.

There is good reason to be somewhat conservative in military cartridge design. Soldiers lives depend upon reliable operation of their weapons. Had I designed 6.5 Grendel, I would've just scaled down the 7x43 British, keeping the 20-degree shoulder.

Or, per the thread topic, scale down the 6.25x43 British to take your idealized 6mm projectile, possibly increasing shoulder angle to 23 degrees.

_ 7x43 British _ 6.25x43 British _ 5.56x45 NATO _

You know the sordid history of small arms development in this country as well as I.

Yeah, I'm somewhat familiar with the subject, having written a book about the development of US Army small arms and ammo. However, unlike many people, I don't view the history as sordid.