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Prepping the big 300gr SMK???

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You want to measure the part of the bullet that is touching the bore bore right? Well, measuring closer to .338 than .330 is not doing that...


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No, not if the the material with minimal distortion has an insignificant frictional component.
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It probably makes no difference though, and I'd bet money it (method) gets lost in the noise...

JB


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Double Ditto - That is Before I read the remarks of <font color="red">uncleB</font>. I put him in the Kirby/GG camp where experience is 10,000 x more important than analysis.

BTW, did you [ QUOTE ]
call John Buhay and see what diameter he makes the holes in the bushings that Tubb sells as the BSC

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It's possible <font color="red">uncleB</font> is right about the superiority of the Tubbs tool but for the wrong reason (but I doubt it.)
 
FYI:

Just got off the phone with Buhay

As I said...

.338 comparator indexes at 0.330 diameter
.308 comp. indexes at .300 diam.
6mm comp. indexes at .256 diam.

"bearing surface" is measured at "Bore" diameter. Believe me now? Straight from the horses mouth.

so who had money ridin' on that one /ubbthreads/images/graemlins/smirk.gif
 
I don't know which would be better, having a tool that measures just the shank of the bullet or slightly below and above the shank as long as it measured that same spot everytime. Every bullet I've ever recovered intact only had rifling marks on the shank as it should be. But there obviously has been research done that led comparator makers to make inserts that measure shy of the shank or what Ub and I were calling the bearing surface.

Either way, when UB and I measured the same 100 bullets using the SP tool and the Tubbs, only about 3 bullets were disagreed upon as to their measurements. This is why I think the SP tool works plenty good! /ubbthreads/images/graemlins/smile.gif
 
Agreed...RE: consistant index point

I don't have the pins to measure my SP inserts, but they are supposed to be "bore" diam too... (.330, .300, .256)

JB
 
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