A 38 Special should be a 357 Special.
A 32-20 should be a 312-20.
A 44 Mag should be a 429 Mag.
The list is long.
Why? And since when has naming cartridges become an exact science. I am talking about working with math and which system is easier to use, especially when precision is considered.
In metric a 38 special could be called the 9mm special, a 44 magnum would be called the 10.896mm magnum. In every instance there is at least one extra number and the fuggin mm! The 32-20 would be the 7.924mm - 20! There is absolutely no basis for calling the metric system better than SAE.