Your not going to find 1 set answer to your question. Some manufacturers state in the manuals not to dry fire, others don't address it. 99% of the time it won't cause a problem, even in those guns where it is not recommended. That 1% that it does can be expensive, especially if it is someone elses gun. Snap caps are not expensive. You could pick up snap cap in the most popular calibers (.380/9mm/.40 S&W and .45 ACP) and put them in your glove box in a zip lock bag.