mkl
Member
I just came across a couple of hole diameter gauges at my local surplus store that measures hole diameter to a thousandth of an inch. I gave $7.50 for a pair that measures from 0.100" through 0.350".
They seem to measure bore diameter just fine. My Winchester 30-30 has a bore diameter of 0.304; my Marlin 30-30 (with micro-groove rifling) measures 0.306; my Mosin-Nagant measures 0.308. Now, since all of these diameters are land-to-land diameters measured at the crown, what the heck can I use them for? I want to determine appropriate bullet diameter for my Mosin, but somehow I don't think adding 0.004 to the land (bore) diameter will work. [Winchester bore = 0.304, bullet = 0.308, hence bore + 0.004 equals grove diameter equals best fit bullet.] (Sigh), yes I know "slug the bore!"
Anyone think of a reloading use for these really neat gauges?
For the courious, here's the URL for the patent (I really have too much time on my hands)
http://patimg2.uspto.gov/.piw?docid...1=2786277.PN.%26OS=PN/2786277%26RS=PN/2786277
They seem to measure bore diameter just fine. My Winchester 30-30 has a bore diameter of 0.304; my Marlin 30-30 (with micro-groove rifling) measures 0.306; my Mosin-Nagant measures 0.308. Now, since all of these diameters are land-to-land diameters measured at the crown, what the heck can I use them for? I want to determine appropriate bullet diameter for my Mosin, but somehow I don't think adding 0.004 to the land (bore) diameter will work. [Winchester bore = 0.304, bullet = 0.308, hence bore + 0.004 equals grove diameter equals best fit bullet.] (Sigh), yes I know "slug the bore!"
Anyone think of a reloading use for these really neat gauges?
For the courious, here's the URL for the patent (I really have too much time on my hands)
http://patimg2.uspto.gov/.piw?docid...1=2786277.PN.%26OS=PN/2786277%26RS=PN/2786277
