First, you must not have a firearm of a specific caliber.
Go to the store and buy several boxes of ammunition of the new caliber.
Wait several days, and you will recognize that something is wrong. There is a very mysterious feeling you have to experience to believe.
You are fully justified in resolving the problem. This technique works!
I bought some .223 Remington a few months ago, and now have a Bushmaster AR-15.
If you have the slightest doubt about my technique, try it at least once. You will be happy you did.
Bill