I figured I’d give everyone a heads up. I recently picked up a H&R 158 Topper in 410. The price was really right. The gun was really dirty, the barrel had some rust but the receiver was in good shape. Except for the fact that I don’t think it has been cleaned in 40 years! (The gun has a manufactured date of 1967). Barrel I planned on re- blueing but the receiver just really needed a good cleaning. The gun oil looks more like shellac than oil! Well I did what I’ve done a thousand times with multiple guns. I have a Lyman ultrasonic cleaner that I fill with simple green and run it for a couple cycles. I have used this combination on multiple guns from Makarov’s, Ruger’s, Smith & Wessons, etc! Never a problem! Well not this time! I ran the receiver through 3 cycles ( 12 minutes) and low and behold it completely removed all the color case hardened finish! The receiver looks like I bead blasted it! Not really a big deal as this is an inexpensive single shot shotgun. I just blued the receiver. I sure am glad it wasn’t some high dollar case hardened antique Winchester receiver! Never had anything like this happen before. No idea why it happened. I’ve used simple green on everything! Anyway just figured I’d give y’all a heads up to be careful what ya use simple green on!