What is the frame size of the Merkel?
Is it used for calibres up to .500?

Yes - the 470 and 500 have the same Rim
diameter - or very close. It's the barrels that
have to be different.

Re Scoping a 375 Merkel - mine is scoped and is used
for more than DG hunting - it is very accurate out to
125 yards which is all I have tried.

375 Doubles are not only used for DG hunting - they
are perfect for deer as well.

500 Nitro