Is the USA changing to all metric?

[John From Detroit]

John,
It appears you might be confusing metric with decimal.

Metric is based on powers of 10 Same as Decimal but the advantage of metric is that it IS based on 10. like the above cm. ("c" For cent) dm (Dime) M (Dollar) KM $1,000.00

 

[TheBar]

Could it be you who is confused?

"The US uses metric in money (100 cents), photography (35 mm film, 50 mm lens), medicine (1 cc of drug), nutrition labels (grams of fat), bottles of soft drink (liter), and volume displacement in engines (liters)."

Info. from here.


-Don- Reno, NV

And ammunition going back over 100 years. The US "calibers" since the 1800's were related to the popular European metric sizes. 9MM needs no explanation. But our 38 caliber is not .38 diameter, it is .357 corresponding to the 9MM diameter. Which is why 357 magnum ammo is interchangeable with 38 Special. And many 38 revolvers now can fire 9MM also. The 30 to 32 calibers are not .30 inches they all range around .312-.315 diameter corresponding to the European ,762-.765 bullets etc.

 

[Larry N.]

The US "calibers" since the 1800's were related to the popular European metric sizes. 9MM needs no explanation.

But my 30 year old .50 caliber Hawken rifle is, indeed, precisely a half inch. We fire a .490" round ball with a 0.10" patch. Measure with a micrometer (except at the edge of the muzzle hole on some rifles) gives 0.50" too.

So it's not exclusively based on metric, even the modern .44 cal and such.

Still, your point is well taken.

 

[Wasillaguy]

We fire a .490" round ball with a 0.10"

You mean 0.01" patch?
Even then, your patch wraps more than 180 degrees around the ball, so cross section would be 0.01 + 0.49 + 0.01 for a total diameter if 0.51.
Compresses to 0.50 when pressed into the barrel.
In reality, patch will often fold or "pleat" on itself somewhat in wrapping around the ball, so actual diameter is probably more like 0.53 before being compressed into the barrel.

 

[Larry N.]

You mean 0.01" patch?

Oops -- you caught my typo- thanks. It's a nice, more complete description of what happens. That compression, of course, keeps the gases behind the ball, providing best propulsion, until it exits the barrel. Sometimes I'll pick the "range daisies*" though I can't always find them all, even when I look. But I've seen some interesting displays made with them.

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*For those who've not seen them, the patches don't go very far down range, usually less than 50 ft, and the black stuff on them (from the barrel) can look a little like a flower pattern. Since the patches are usually yellow...