I think my head is going to explode............(updated, sort of, post 32)

[jmoore]

The usual criterion for barrel-stock freedom is being able to slide a postcard around everywhere without it binding. I don't see any need for 2mm clearance all round - or have I misunderstood something?

Yes. Misunderstood the addition of a midlength ported gas system hung by easily servicable, but not accuracy enhancing, means to a lightweight barrel connected to an even more easily disassembled action that is barely mated to flexible stock. About as not like a bolt action rifle as is possible whilst still remaining fairly "traditional" in role and contruction.

The Garand's gas system, being far further forward, has less opportunity to disrupt things in a dynamic manner whilst the bullet is still in the barrel. It also has much more action support in the stock due to it's longer and thicker legs than the M14. Both have very light action bodies which receive firing recoil impact, plus bolt rearward and forward impacts during the loading cycle. Even a well glass-bedded, double lugged M14 action's heel will flex upwards over 0.004-0.005" off the stock when the bolt hits!

There's more! Off axis flexing due to the assymetrical nature of the op rod, mid band centering, op rod to gas piston positioning rotationally, as well as longitudinally, gas piston to gas cylinder fit, spline tightness, Non uniform stock to action fits amongst and even within the various commercial action manufacturers, damping effects of various barrel lengths, weights and attachments- and that's just things off the top of my head.

These rifles can shoot well, but they can also be quite the nightmare. Personally, I think it's worth the trouble. Too bad it's far too late for a third generation with all the lessons learned over the past fifty years incorporated into a new military platform.