Getting accurate measurements

OK I decided to try getting new measurements on my Pedersoli Sharps Buffalo 45-70. I used my dial calipers on a Cerrosafe chamber cast last time and it gave me a diameter of .458. I took this as my bore diameter which was probably incorrect. I probably measured from a land to groove and got the .458 reading. [smilie=b: Anyways decided I need to measure the muzzle exit so in looking at what I had that might work I dropped a .454 255 pistol bullet into the muzzle and it wouldn't fit.:confused: So I got my mold out dropped some pure lead in it and made a slug. Drove the slug about 2" down and then back out. Had nice clean defined rifle grooves. I measured the grooves and got .452. Does that sound correct? Have the Pedersoli barrels been known to be choked down? Now trying to figure out what size slicks to try out with PP is spinning again. OMG why did I decide to chase the rabbit? :brokenima

Slug with pure lead. I slug 2-3" ahead of chamber then back out this gives breech end dia. Then 2-3" in from muzzle this gives th e muzzle end. then one thru the barrel, this shows the tightest spot in the barrel.
Count lands or grooves 3 5 7 takes a different approach to measure.
if even and 180* across then a standard micrometer can be used maybe. :-P You may need a set of blade or point mics to get in the bottom of the grooves. Calipers will give an idea but arnt as accurate.

Another to get bore dia is a set of pin gages. Or play with paper thicknesses on your bullet until one fits just right. For this you dont need actual wrapping paper just different thicknesses. when you think your close at he breech end wrap one the same and push thr the bore and see if it has marks down it..

Without going into a long explanation, Pedersoli make their barrels with progressive depth rifling. The bore is 0.452"/0.458" and 0.450"/0.458" at the muzzle so that as the projectile travels down the barrel the rifling gets deeper.

https://www.youtube.com/watch?v=eOo-muzMRp0

https://www.youtube.com/watch?v=TOLzOSaBW2s

Quote:

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Originally Posted by Bad *** Wallace

Without going into a long explanation, Pedersoli make their barrels with progressive depth rifling. The bore is 0.452"/0.458" and 0.450"/0.458" at the muzzle so that as the projectile travels down the barrel the rifling gets deeper.

https://www.youtube.com/watch?v=eOo-muzMRp0

https://www.youtube.com/watch?v=TOLzOSaBW2s

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Now my measurements make sense to me. Thank you and the videos were interesting also. My bore is not even close to the mirror shine as in the last video. It still shoots better than me though.

Put a couple hundred PP rounds down it then look at it, it will shine right up.