[dtroy229]

If I had 2 guns (same make and model) that used the same make and model of bullets, would they produce different results when each was fired? Is there a way to tell which bullet was fired from which gun?

[KISS]

They each should have a different wear pattern in the barrel. That induces a different wear pattern on each bullet. Now if they were both new guns, it might be tough, but might still be possible.

You may have to fire another bullet and compare them.

Same deal with a typewriter, the number of times each letter was hit changes the wear pattern on the heads.

[WVHiflyer]

While identical firearms would supposedly have the same rifling (spiral features in the barrel to improve accuracy), minute differences cause by the manufacturing process would probably enable an expert to tell them apart. The more times a weapon is fired, the greater the differences become.