Impact Impressions Using Squib Rods

[Hinnerk]

The recent issue of The Fouling Shot contained a description by C.E. "Ed" Harris of making an impact impression using a Brownell's Squib Rod screwed into a cleaning rod and repeatedly dropped down the barrel of a rifle upon a dead soft lead slug until it starts to ring. Anyone else ever tried it that way (rather than using a long rod and a hammer)?

[wmitty]

I’ve used a piece of 1/4” brazing rod in a .30 cal barrel to expand the lead. The rod will bounce once the lead has compressed/expanded.