Nominal bore sizes

R

Rflshootr

Member
Does anyone have a list of nominal bore sizes of the various calibers? Or is there a standard formula to figure this such as groove diameter-.008 or such? I'm in the process of making various bushings for a piloted crown cutter.
 
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If you go to the Krieger Barrels website and click on calibers and barrels, the spreadsheet shows their specs including bore and groove diameter. Other makers use different sizes, sometimes as much as .002 on the bore diameter. To fit the pilot closely to a lot of different barrels may require a selection of bushings. PTG does have a list of nominal sizes, their website is under construction right now, but if you drop them an email, they will probably respond.

Scott
 
Groove diameters are held pretty close throughout the industry, since that is the criticle diameter. Bore sizes can vary as much as .0005 beteween barrels from the same manufacturer, sometimes from ther same lot. I have had .237 6MM kriegers have a bore diameter as small as .2366 and as large as .2374.

What material are you planning on using. A pilot must be hardenned so as to not allow small particles to impregnate that could damage the barrel.........jackie
 
Jackie, I hav some A-2 & some 4140 that is preheat treated to 43Rc. I think I'll try the 4140 1st & see how my HSS reamer cuts it. If it is too tough, then I'll have to go the A-2 route.
 
Butch it's a long story, but I have 2 hours every day at work to kill before I'm on the clock. So in short........yep I'm bored.
 
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