.308 vs .309 in .308win

[B2Busy]

SAAMI specifies that the .308 win bullet dia should be .309. and .308 clearly is the groove diameter.
Why does the industry clearly prefer .308 dia bullets contrary to the SAAMI spec of .309?
I found that by using a .308 Lee resizing die on 3.10 Dia bullets pulled from 7.62x39 rounds I get a .309 dia bullet. Don't know why and don't really care. But I am just wondering if there is a reason that the most expert bullet makers in the world; Hornady, Barnes, Sierra and others all make the bullets in .308 dia when the SAAMI spec is for a .309 bullet down a .308 hole. did they find that SAAMI is wrong?
There must be less barrell wear and sufficcient seal.
I have found that I can obtain .310 dia 123 gr bullets and wonder if using that process would have any advantage over 308 bullets.
would that just wear out the barrell sooner?

[J-cat]

I thnk .309" is max. The range is .306" to .309".

[B2Busy]

I thnk .309" is max. The range is .306" to .309".

THe Saami Specification is .309 +- .003, so .308 is clearly outside if the spec.

[J-cat]

It's .309" minus .003"

[jumbopanda]

SAAMI specs don't always dictate actual manufacturing practices in the gun industry. For example, Glock cuts the chambers in their barrels larger than max SAAMI spec.

SAAMI bullet size specs are pretty odd. They allow for a 0.003" tolerance in every caliber I've bothered to look up their specs for, but no bullet manufacturer is going to allow that kind of variation in their products.

[J-cat]

Not in their 9mm barrels.

[thenodnarb]

I pulled a round of M2 Ball from 1944 apart and the bullet diameter was .307 FWIW

[3RDGEARGRNDRR]

I agree. All the ammo manufacturers dont know what they are doing.
0.309+/- 0.003. Cool
Im running .312 in my m1a

[B2Busy]

THe Saami Specification is .309 +- .003, so .308 is clearly outside if the spec.

double checking Saami drawings and my math, I agree that the spec IS .306 to .309.
So I guess that the .308 makes more sense due to it matching the grove dia. thanks to all contributors.

[bohoki]

i thought the 309 is round or soft tip for tube fed safety