Longbow, I was a big fan of the Brenneke slugs ... and part of it is family history. My grandfather would hunt boars with the Brenneke around 40 years ago.
I remember, he allowed me to take one of those cartridges apart ... around 40 years ago ... as an educational experiment ... and according to my recollection ... what is loaded in the Rio Royal Brenneke is exactly what I found 40 years ago in that shell ... a Brenneke slug with a felt wad ... some plastic/rubber washers ... and all screwed together with a normal screw.
And the Rio projectile ... is an original Brenneke ....
Attachment 207570
Attachment 207571
Today, I don't hunt with the Brenneke any more .... my tests have lead me to other type of slugs.
1.) For accuracy the Federal TruBall seems to be the most accurate for me ... and that is what I am using now for deer hunting. I haven't found anything that is more accurate ...
2.) And the Challenger (Gualandi) slug was the clear winner of my penetration test ... and that is what I am carrying nowadays for bears ... and just in case. The Challenger is not accurate (or at least it was not as accurate for me) ... but the Challenger has shown the deepest penetration ...
The Brenneke is not a bad slug .... I believe it has proven itself over many many years ... but my tests have shown me that today there are better options out there ... for accuracy and for penetration. And the Challenger and the TruBall are much more accessible here in Canada ... Brennekes are so hard to find north of the 49th parallel ....
I have never shot the Brenneke Classics ... but I would assume that the projectile is identical to what Rio loaded in their shells ...
Voila, hope this helps ...
Faustus
p.s.: I still have a lot of Rio Brennekes in storage here .... and which I would be willing to sell ... if you are interested.