The best way to tell is to simply look at the gun. Modern 37's have their caliber listed on the barrel. I have heard of some 37's having the +p marking, but I own one that does not.
Next, I would advise you that using +P ammo in most airweights is a bad idea! The 37 I have will handle them fine, but it causes more issues upon ejecting spent cartridges etc. The idea is that the long term repercussions are too stiff to use +p on a consistent basis. If you are going to use a good +p round to carry on a daily basis, then that might be fine, but I would NOT go to the range and practice with that type of ammo!
Stick with a good 38 round! the +P doesn't create all that big a difference, if you make a good shot!
100-450 USD
45 years old
69-70
Someone modified it.
100-500 USD
$20
Made in 1953. Model Numbers did not come into use unitl @ 1957. Sounds like you have a Chief Special Airweight. Later numbered as a Model 37.
Informaiton not available in the public domain.
100-450 USD
50-475 usd
Up unitl @ 1957 model numbers were not used. Check inside the frame near the crane, it has a model number, it will be there.
You need to find a gunsmith or firearms instructor