The first tag was referring to an unfired shell length , the 2nd, was to a fired shell length. what we call todays shells. go measure an unfired shell it will be shorter than 2 3/4 "

Bruce,Your model 12 shot the Remingtons because their 16 dove and quail loads actually measure 21/4" unfired and 21/2" fired. They are 21/2" shells even though the box says 23/4". I have shot them in damascus 16 gauge guns for years.

The Remington 16 Game Loads with black-colored hulls typically measure 2.611-15" (2-5/8 inch) when fired. Furthermore in reference to early Model 12's their 6-point crimp somewhat contracts on firing and will usually clear the front of the ejection opening. On the other hand some other shells such as blue-color Fiocchis have full 2-3/4" long hulls and crimps that fully expand. The latter and other similar shells can hang up and cause no end of headaches in Model 12/16-gauge pump guns.

I just measured the shells again to be sure. Unfired is 21/4" and fired is 21/2". I have seen these fired in short chambered model 12s and A5s. I am sure there are manufacturing tolerances that might cause hang ups. I am just reporting what I have seen.

Here's a random/once fired 16-gauge Rem Game load hull from my box of empties. Caliper reads 2.615" or a nominal 2-5/8". Note how the crimp slightly contracts which also helps to clear the ejection opening in M12/16-gauge receivers. Both as written here earlier.