Hello, All!

I am curious about the history of how the bullet weights for 9mm and other calibers were established. Why 124, instead of 125? (Yes, I know there are some 125s out there.) Why 147, instead of 145 or 150? 38 spls are usually 148 or 158. Why not 150 or 160?

Like I said, I'm just curious how those became the standards. Anyone know the history?

Thanks!

GB.

If you did the conversion to metric units of measure (grams) you would probably find nice, round numbers for the bullet weights.

I think the 115 is a western innovation, but 124 is approx. 8 grams and 147 is approx 9.5

64.798 grains = 1 milligram.

Doing the conversion gives you:

115 grains = 7.45 grams or approximately 7.4 grams
124 grains = 8.034 grams or approximately 8 grams
148 grains = 9.59 grams or approximately 9.5 grams
158 grains =10.238 grams or approximately 10.24 grams

I am reasonably sure that these odd bullet weight numbers were standardized in accordance with european metric conventions, and then converted to the US avoidupois units of measure.

You will find similar weight conventions on all european calibers, where bullet weight is expressed in grams.

You can also ask yourself why not 130 gr. in 9mm? 38 Super comes in 130 gr bullets, .355 diameter same as 9mm.

The 115 gr and 124 gr weights are historic legacies. 9mm ammo specs in europe frequently established a required weight range, energy minimum and pressure maximum and left the details up to the ammo companies. As previously noted, those weights were in grams and the resulting English system weights derived from those. Cartidges of the World (book) or Wikipedia will probably tell you more than you want to know, with Wiki being a wee bit suspect. You also have to recall that 102 years ago, the selection of available powders was limited and this affected the weights of bullets that could reasonably be used at acceptable pressures.

The 147 gr load is the result of much more recent work to develop sub-sonic rounds for use in suppressed submachine guns for special operations work. Figure the 1970-1980 time frame. I believe it's also adapted to pistol operation as some of the original stuff was unacceptably anemic in handguns.

As noted earlier, books have been written on this subject. Check your local library or bookstore.

Wouldn't 7.45 round to 7.5
and
9.59 round to 9.6 ??

__________________
Occam's Razor