Anyone seen this before?

[u/TheJurgg]

Never seen this on a shotgun shell before today. Testing out a 30 round drum mag on a Canuck Recon 3 and about 8-9 shells out of 60 had this damage on it. Had a lot of double feeds and it looked like the extractor was catching the 2nd bottom round and is probably what did this.

[u/IfImBitchyImDrunk]

That's concerning... Personally I'd bring the firearm and some shells to a gunsmith.