Numskull -- my plug has brass also. I was surprised to see the 1/4" lead. Again, the secret is in the lip! I have 10 or 20 that I made that were junk. I tried everything to get the lip right and finally used a dremel with a flapper sanding wheel to shape it to where it works well.
It is a good plug in the ditch when the current is just right. You can feel it wiggling like mad. Casts like a rocket also.
Thanks for the x-ray - very helpful.
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