On Wed, 21 Aug 2019 00:17:30 -0700 (PDT), Chalo
wrote:

John B. Slocomb wrote:

Nope. The "NAS" number has changed but the same old bolt is still
available. A NAS 147-53 is now called a MS25007-40

The AN- Army Navy specification series started in the early 1940s
NAS-
National Aerospace Standards, started
in 1941
MS- Military standard started around
the 1950s

That conveniently ignores the fact that a 1/4"-28 screw isn't an M6x1.0 screw. There is no metric "internal wrenching bolt" so there's no such bolt on a recently manufactured bicycle (even a pretend bicycle like a Huffy).

Well, it wouldn't be would it. It would be an M6.34 x 0.907 bolt/screw
:-)

I think that you may be correct, there doesn't seem to be a "metric
internal wrenching bolt" but there is a "metric socket head screw"
https://en.wikipedia.org/wiki/ISO_metric_screw_thread
And of course, the "socket head" description would indicate to most
mechanics that it was "internal wrenching".
--

Cheers,

John B.