14 gauge shotgun shells have not been commercially available in the US since the 1920's and there probably hasn't been a gun chambered for them made since WWI. If you want to give a little more information - like all the writing and symbols found on the gun, I can probably tell you a bit more.
http://www.histandard.info/PDF/Sears%20Shotguns.pdf
Oh, dude, that's like asking me to calculate the square root of a watermelon. A shotgun stamped Cracker Jack Southern Arms Company dated Aug 14, 1900, with a 14-gauge stamp is technically a 12-gauge shotgun. The 14-gauge stamp was a common practice back then to indicate the bore size, but it's actually a 12-gauge shotgun. So, like, it's worth whatever someone is willing to pay for a vintage shotgun that's a bit confused about its own gauge.
Very late in the 1800's
Assuming this is a firearms question- the 14 gauge shotgun is very rare today. The bore diameter is smaller than a 12 g, larger than a 16g, and runs ABOUT 0.695 inches. That converts to about 17.65mm. If you are seeking to convert wire gauge, or sheet metal gauge to mm, please repost with that information.
50-100 USD
50-100 or so
The value of a London Fine Damascus 14 gauge double barrel shotgun marked JT Sang Ford depend on its condition. This gun in excellent condition is valued between 225.00 and 320.00 as of 2014.
if it's 14-gauge then it's 14-gauge.
There were a very few 14 g Mdl 59s made by Winchester. It is an extremely rare gun.
You should use a taper. You can probably find these at a piercing studio. It is important to first stretch it to a 16 gauge, and then to a 14 gauge about a month later to prevent tearing.
I am not sure on the price because i am also looking for a price for i have a full box of FMC 14 gauge shells #7.5 shot. If interested e-mail @ jjbct@hotmail.com
You can find 14 gauge needles for sale at medical supply stores, online retailers, and some pharmacies. Many tattoo and piercing studios also carry 14 gauge needles for body modifications.