Ruger GP100 bore

[Ghost101]

I slugged the bore on my GP100 last night an found it to be 5 grooves instead of 6. How do I measure the bore size? Seems I have read about a V-block or something along those lines .

Ghost101

[huntrick64]

Slug it as usual, then you take some brass shim stock that is thin enough to bend around boolit but rigid enough to not collapse between the ridges left from the rifles grooves. Mic that and then subtract the two thicknesses of the shim stick. .002 shim stock works pretty good just cut the shim stock width to be the height of the bearing surfaces of the bullet.

[Pepe Ray]

"V"-block guages are available from Ken (45Nut). For 5 L&G bbls only.
Pepe Ray

[Ghost101]

I will give the shim stock a try. Sounds great an thank you Huntrick. Peep Ray thanks for the V-Block info. Life is once again good.

Ghost101

[fecmech]

If you carefully rotate the bullet you can catch the edge of opposite rifling grooves on 5 groove bullets and get good readings with your mic. You will just be going off of one groove and just coming on to another, give it a try. I have done it on both S&W's and Rugers.

[Ghost101]

Thank you fecmeck, I will do that, this evening. Glad that I have a holder for my mic . Now I'll have to just figure out a way to rig a magnifier, lol .


Ghost101