doublegunshop.com - home Forums General Discussion German & Austrian Sporting Guns @ doublegunshop.com O/U - Bockbüchsflinte Rifle Caliber Question

I suggest someone make a chamber cast to determine the nominal cartridge for this rifle. The 6,3 is proper for the 6.5x52R(25-35), but the absence of a case length is troubling as is groove diameter determined by slugging the barrel (0.261"). Depending on barrel markings alone sometimes causes confusion between 6.5x52R(25-35Winchester) and 6.5x58R. Most 6.5x58R rifles take a bullet smaller than the normal 6.5 bullet diameter of 0.264" but larger than the normal 25 caliber diameter of 0.257". My own takes a 0.260" bullet but many (maybe more) take a 0.261" bullet, neither of which are commercially available, so some handloaders are advised to use 0.257" bullets. Other handloaders resize 0.264"(6.5mm) bullets to the diameter required by their rifle. To make the confusion even worse, 6.5x58R is mostly loaded in 30-30 head size cases, which includes 25-35Winchester. I resize original length 38-55 cases and modify the rims to fit (which removes the headstamp). If a prior owner modified the rim recess to accept American rims, it is easy to see how a 6.5x58R rifle could come with ammo loaded in cases with 25-35 headstamps and 0.257" bullets. The 6,5x52R is a necked case and the 6.5x58R is a straight tapered case. A chamber cast will show the nominal caliber. Also, a factory loaded 25-35 will not chamber in a 6.5x58R, but a 6.5x58R cartridge loaded in a(shorter) 25-35 case with a 0.257" bullet will likely chamber in a 6.5x52R rifle (and if fired would fireform back to a necked case). To quote the King of Siam, "is a puzzlement".
Mike