Damfino. I'll take the buttplate off and have a look - the rifle handles like it has something of weight in the butt (though it balances very well) - still, I had not heard that any of the Merkels came with a recoil reducer. I'll let you know what I find.
mhb - Mike

Later:
Well, I carried out an investigation to find out what, if anything, lies beneath the Merkel's buttplate. What I found could be described as 'recoil reduction devices', in the strictest physical sense (added mass in the rifle reduces recoil velocity and thereby, felt recoil). The contents were:
1. A lead slug, possibly cast in-situ in the top of the stock, diameter 15mm, length unknown, but possibly up to 8" or so, with a gap between the rear end of the slug and the buttplate of about 3/4". As there was no obvious means of removal, and the slug seemed fixed in place firmly (a good idea, given the recoil of the rifle, I can't say more about it.
2. A steel slug, .750" in diameter, and 7 1/8" in length, just below centerline of the stock, and retained in place by an oval steel plate at the butt end, with a metal screw through the plate into the slug, and a wood screw above the slug through the plate into the stock - an arrangement obviously intended, again, to prevent shifting under recoil.
The forward end of the slug featured an encircling O-ring (to locate the slug in the hole), and a counterbore which provided clearance for an Allen-headed bolt visible in the bottom of the hole (stock bolt?).

So, there is nothing in there which could be described as a modern 'recoil reducer', but the extra weight is both necessary and welcome (in my opinion). I'm gonna have to get a good, accurate scale so I can weigh the rifle - I am VERY curious to know just how much it does weigh.
mhb - Mike