Doubly-so if it's a several pound metal ball...
You don't want to hit anything in an aircraft, ever.
https://warbirdsnews.com/warbird-restorations/caf-bell-p-63f...
But, I would not be surprised it was tried, particularly with WWII era machines. There's very little actual benefit to having one on any aircraft, even CAS aircraft. A modernly restored version meant for airshows and racing probably would have replaced it for something more modern and lighter weight.
There's no particular reason for wikipedia to mention it because it was a very common feature in this era. It would be like mentioning that it had self-sealing fuel tanks. It was also a feature that could be present or not between different models, and could even be retrofitted to a plane once it was in service.
Regarding the wreck-finder below: he likely does know exactly what it was because he likely started by looking up the crash report (and based on his claimed date, it's probably s/n, 44-2031)
This is exactly what a typical armored windscreen looked like in this era (e.g. https://ww2aircraft.net/forum/threads/armored-windscreen-for...)
The P-63 did (example picture [0]), like many others that were designed to attack bombers and/or ground targets.
Regardless, modernly speaking, very few (if any) aircraft have bullet proof windshields. They are impractical for a number of reasons, including weight, size, thickness (distortion of picture), and efficacy. If a pilot is within small-arms distance they generally are already in trouble...
