I tend to think it has something to do with the safety pushrod. I mentioned earlier that I thought it could have something to do with a means of deactivating the safety. Toby Barclay also mentioned the possibility of this being a pin hole for a safety pushrod retainer/guidepin, and that makes sense to me. But I can't imagine why it would not be a blind hole if that was the case. I'd think if it was inadvertently drilled clear through, the maker would have simply welded it closed and tried again, rather than leave a glaring mistake on the topstrap. Again, I could be 100% wrong, and have not seen every shotgun's innards to say for sure. Do you know what make it is?
