A cartridge for a shotgun. Typically loaded with multiple lead balls (shot).
It is a shell for a shotgun that has less power than a standard shotshell, and produces less recoil, or "kick".
you will have to do a web search on 44 shotshell ammunition.
shotshell
A shotshell.
Using the wrong shotshell in the wrong shotgun.
No. It's could cause damage.
the species you will be hunting
Modern production Citori 525s are offered in 2 3/4 and 3 inch chambers. Shotshell pressure is governed by SAAMI which states 11,500 psi for all 12 gauges except 3 1/2 magnum rounds.
It might fit, but why would you want to do that. It has no gun powder and won't fire.
#11 cap originally but there are conversions for them to use larger 209 shotshell primers to ignit pellets better.
By 870 I assume you mean the Model 870 shotgun? If so, there would be no purpose for that type of conversion. Shotshell primers are of the 209 size. The 209 "conversion" is done with muzzle loaders. The idea is to replace the muzzle loader nipple (that holds the cap) with a conversion unit that uses the 209 shotshell primer to get more positive ignition of the black powder.
No. However, if you are a "prohibited person" it is illegal for you to possess 209 shotshell primers. Percussion caps are OK, 209 primers are not.