If there was a mag ban that limited magazines to 10 rounds, would current smaller caliber users switch to a larger caliber? Why or why not?
This question was on the minds of a lot of folks when the fed law and CA's state law was introduced (CA still has their law in effect).
The upshot of it was that some folks thought "yes", and some "folks thought "no" ... and now many years later, the 9mm is still a highly popular caliber in CA.
Now, in my case, I was a cop when those laws were enacted, so it didn't affect me regarding being able to buy, own and use hi-cap magazines. Current CA law allows me to keep my older ones as retired LE, as well.
I own nine .45's, five .40's and six 9's, the majority of which were bought after the fed & state bans had gone into effect. As much as I'm a longtime .45 owner/shooter (and carried a couple of issued ones), I much prefer the smaller & lighter 9's when it comes to retirement CCW nowadays.
So, I guess it didn't - doesn't - matter ...
to me.
FWIW, here in CA there was an attempt last year, which narrowly failed, to make the 'grand fathered' pre-ban hi-cap magazines illegal. (Yes, this would've also removed the retired LE exemption.) There's possibly going to be another attempt next year (ballot measure, if it gets enough votes). There have also been 3 cities who have passed their own city ordinances against the pre-ban mags, too (one of which doesn't contain an exemption for retired LE).
Having seen the hand-writing on the wall, last year I placed an order for quite a few 10-rd mags for my one hi-cap gun, just in case the 12-rd mags become illegal for me to continue to own.
When it comes right down to it, since I started in LE work carrying 6-shot revolvers on & off-duty, and a 7+1 Colt Commander off-duty, I consider most pistols that hold more than 7 or 8 rounds in the magazine to be "hi-cap" pistols.
Even back in the days when the double stack S&W M59 was seeing LE use, and the Browning HP was popular for off-duty, the single stack M39 was still seeing a lot of LE use. I knew quite a few guys who could've carried the M59's, but chose to carry the M39's.
Guess it's a matter of perspective.