With all due respect to Bruce Buck and his Junior Technoid magic slide rule ring, I disagree. His answer overstates the results by a factor of 2. In a pair of 28" barrels the bore is length , less chamber and forcing cone, less choke and choke cone, @ 24.5 inches.Using metric units @ 25.4mm/"-2.54cm/" and a cylinder volume formulae of R2 x pi x L I come up with
a.As recvd .729"dia = 18.52mm, r=9.26mm r sqd=85.74mm2 x 3.142=
269.4mm2 or 2.69 cm2 x length 62.23cm Volume #1=167.40 cm3
b After .010" overbore to .739"/18.77mm r=9.3853 sqd =88.08x pi 3,142 =276.76 mm2 or 2.77cm2 x l 62.23cm =172.37cm3 for volume #2
Vol 2 - Vol 1 = 4.97cm3. Steel has an sg of 7.35 gms/cm3 for 36.53 gms. Grams/ oz = 28.35 or 1.3 ounces per tube lighter.
Aditional 2" for 30"bbls = a further reduction of 1/10oz/tube
slightly less for choke and cone opening additional .010".
Of further note I dont see many European Game guns with .030" thick walls let alone the .040" he quotes as common.
Proceed with caution and do not expect major weight loss!!
Regards to all from a Non PhD
