US Military choice of .300 WinMag over .338 Lapua

[Tony Williams]

Only one article that I have read suggests that other factors come into play. In this article (from the same site you referenced) one shooter expressed his thoughts that a long case neck could reduce barrel wear.

That was one of the reasons for selecting the Norma round given by the GD team at the 2012 presentation in Seattle, but it was subsequently dismissed by Lapua. In fact, if you compare the two rounds side-by-side, there is very little difference in the neck length.

[bwaites]

I like both cartridges, and I like the fact that the Norma will go into shorter actions. One of my concerns with that is that simply shoving it into an action designed for a smaller and lighter cartridge might not be really safe.

I suspect that even the actions typically used by the longer Lapua are borderline safe, simply because there isn't enough metal around the cartridge. I'm no metallurgist or engineer, but it seems to me that more steel is better when you start talking about the case diameters of these cartridges.

Maybe LRRPF can chime in on hoop stresses of a 1-1.25 inch diameter action stressed by these cartridges?

[nincomp]

Had General Dynamics actually performed barrel wear tests or just guessed?

[nincomp]

I like both cartridges, and I like the fact that the Norma will go into shorter actions. One of my concerns with that is that simply shoving it into an action designed for a smaller and lighter cartridge might not be really safe.

I suspect that even the actions typically used by the longer Lapua are borderline safe, simply because there isn't enough metal around the cartridge. I'm no metallurgist or engineer, but it seems to me that more steel is better when you start talking about the case diameters of these cartridges.

What is the COAL typically used for the .338 NM and for the .338 LM? I have seen two: 3.600 and 3.681".

I hope that LRRPF will let us know how much duct tape should be used to provide the necessary margin of safety.

I noticed that there is also general concern about lug strength. Now we will need JB Weld suggestions.

[cory]

I like both cartridges, and I like the fact that the Norma will go into shorter actions. One of my concerns with that is that simply shoving it into an action designed for a smaller and lighter cartridge might not be really safe.

I suspect that even the actions typically used by the longer Lapua are borderline safe, simply because there isn't enough metal around the cartridge. I'm no metallurgist or engineer, but it seems to me that more steel is better when you start talking about the case diameters of these cartridges.

Maybe LRRPF can chime in on hoop stresses of a 1-1.25 inch diameter action stressed by these cartridges?

It's a pretty simple calculation.



σ(hoop) = p d / 2 t

where

σ(hoop) = hoop stress (MPa, psi)

p = internal pressure in the tube or cylinder (MPa, psi)

d = internal diameter of tube or cylinder (mm, in)

t = tube or cylinder wall thickness (mm, in) (outer diameter minus inner diameter)

Ideally you want sigma to be less than half of the yield stress of the material used.

[nincomp]

Maybe LRRPF can chime in on hoop stresses of a 1-1.25 inch diameter action stressed by these cartridges?

It seems that 1.12" is not enough when a cleaning rod is left in the barrel.

http://bulletin.accurateshooter.com/2014/02/cleaning-rod-in-barrel-causes-catastrophic-338-lm-kaboom/

[LRRPF52]

http://lassengunsmithing.com/html/CylinderStress.htm