Home Forums Hunting & Shooting Ask The Gunwriters Where can I find .285 cal. bullets?

When Mauser developed the 7x57, they established the minimum groove diameter as 0.2854 with a max of about 0.289. This was long before CIP or SAAMI existed. The three Oberndorf Model 98s I have had in 7x57 each had groove diameters of 0.2854”. One from 1908, two from 1935. The VZ 24s I have had in 7x57 had groove diameters of 0.287. A new 19” FN replacement barrel has grooves of .289+. Why the US settled on .284 is a mystery to me. Woodleigh has cataloged 160 and 175 grain bullets of .287 diameter, advertising them for the .280 Ross. Which makes me think Ross either used Mauser barrels or maybe rechambered a Mauser 7mm rifle for his development work. As others have stated here, the Nosler partitions do well when fired in rifles with the European bore dimensions, as do older “cup and core” bullets as made by Speer or Sierra which you can find sometimes at gun shows. Once while searching on the net for the diameter of 7mm bullets I found a reference citing an order from Brazil for a bazillion 7x57 cartridges, loaded with 162 gr boat tail bullets to a velocity of 2660 fps and with a diameter of 0.286”.