[Allen Humphrey]

I’ve seen this discussion numerous times on this site and others and the .308Win always seems to get the nod. Nearly every discussion revolves around the efficiency of the .308Win cartridge and reduced recoil. Those are not difficult to understand or believe. What surprises me is that nobody discusses the chamber, or more specifically the throat area.

Nearly ever modern cartridge chamber (including 308Win) follows the same configuration.
1. A short straight section of parallel freebore just slightly bigger than caliber groove size followed by...
2. A tapered lead section between 1 and 2 degrees to the caliber dimension

The 30-06 chamber follows the much older design pattern of having no parallel freebore and instead uses a tapered throat from the case neck down to the caliber dimension. This makes me think the 30-06 has maybe been held back by this throat design in service rifle type matches. Thoughts?

 

[Allen Humphrey]

I think the fact that many competitive shooters re-barreling their M1s to .308 speaks volumes

Art- I fully agree on this. Even if the “mechanical” potential accuracy between the two was identical, I think the reduced recoil and economics (less powder to buy per shot) would cause the 308 to be the logical choice.



What got me thinking about this topic was my 308 Garand that is all NM tricked out, including a heavy Krieger barrel. Given that heavy Garand barrels are nearly extinct, could I get a few more thousand rounds of peak performance by reaming out to a match 30-06 chamber and running a ported gas plug? The chamber that Random Guy posted was what I was looking at.

 

[Allen Humphrey]

Lysander,
Thanks for posting that information. Didn’t realize the M1 had that chamber. Did that design go back to the inception of the Garand, or did it come later?

 

[Allen Humphrey]

Frank- thanks for the thoughtful response. I think your comments/experience align with my belief about a good chamber bringing excellent accuracy to 30-06. The chamber you describe sounds like a good one (30-06HVT). That would be fun to try out in a M1903 USMC sniper clone too. I have not put a new 30-06 barrel on a Garand or 1903 in a while, but those used the SAAMI reamer. They shoot well for what they are, but next time it will be something better like the HVT. I also think my rechambering plan might have merit when the 308 throat is smoked....unless of course you start making some M1 Garand heavies..