Since reading the Range Report thread in which the topic cam up about oversize chambers, I decided to do some digging into my .204 brass . I noticed that factory hornady brass , is hardly noticable compared to my winchester brass . So I broke out the calipers and measured :Winny new brass case head is .3725, fired hornady .374 ,directly under the rim is new winny .3695 , fired winny .370 , fired hornady .372 . The largest point in the bulge : fired hornady .376 , fired winny .377 . cartridge dimension for this area is supposed to be .3764 . Seems like my brass is actually undersize , with winny being the worse . Does anyone have any new hornady or remington brass they can measure ?? It definately seems the hornady is closer to spec , and probably all around better brass , but I can buy it as loaded ammo almost as cheap as brass !! The other post was about .243 and considering its been around forever , I doubt its the brass but you never know .