7:54
On Mon, 17 Apr 2017 15:24:41 -0700 (PDT), Tim
wrote:
- show quoted text -
The Brits made a 22,000 lb penetrator to break the sub pens on the
French coast too. It was basically a gun barrel, stuffed with Torpex
and a sharp cone welded in the nose. It used a tail fuze with a time
delay around a quarter to half a second. They also had a rocket
assisted bomb that came in a bit faster.
They didn't really know how well they worked until after the war and
they got a look inside the pens.
.....

Yeah, I'd say they both had the same idea producing the same effect[s]