Looking for some measurements for 870 barrels

[Synchronizor]

I'm working on a video that focuses on barrel lengths, and one of the things I'm going to mention is that the barrel guide ring on 870s can be used as a reference, allowing barrel length to be measured without taking the gun apart or sticking anything down the bore. On standard 12ga 870 barrels, the front face of the guide ring is 11.75 inches (about 298 mm) from the closed breechface (or the back end of the barrel, not counting the barrel extension).


This has been the case for every standard 870 barrel I've measured, but I haven't had the chance to take apart & measure every version of the 870, and I can only be so accurate deriving measurements from online pictures (thanks to aptly-named barrel distortion). So, I wanted to see if any members here would be willing to measure their barrels and post their results. Data from any 870 would help confirm my findings, but I'm especially interested in numbers for less common 16ga, 28ga, & .410 870s, and models with non-standard magazines like the 870 MCS and Special Field.

I'd also be interested lengths of magazine tubes (as measured from the front face of the receiver), and barrel extensions (the bit that extends backward from the chamber, and fits into the receiver).