Does anyone know the S&W factory design specifications and tolerance for bore diameter in the .357/.38 and .44?
What is the design bullet engagement in the rifleing for a lead bullet versus a jacketed bullet?
Hornady lists the bullet diameter for .357/.38 as .357" and for the .44 as .430"
I have noticed that my hard cast lead bullets from our local producer are .358" and .431".
The Hornady HP-XTPs in 158 and 300 grains measure out at .357 and .430.
These measurements indicate to me that the lead bullets engage the rifleing by .0005" and the XTP's do not engage the rifleing.
Why have the lead bullets engage the grooves and not the jacketed? I would think the copper is soft enough to do so. Maybe it is necessary for one but not the other. I see the lead bullet as holding back pressure leakage better, but also having more friction loss in the barrel.
The .357 and .430 bullets don't fit into the barrels of my 686 and 629, so the barrel diameter is obviously less, but I can't measure it accurately without a plug gauge. I guess this goes back to my first question. What is the factory shooting for on bore diameter and how much tolerance is allowed in manufacture?
Just curious as to how all this works together. I am that kind of person, unfortunately
Thanks