The Remington 90-t is a 12 gauge, single shot, break open, trap shotgun
Value of any firearm is based on the current condition of that particular firearm.
Dimensionally similar, but they are not exactly the same. A firearm with a 5.56x45 chamber can accommodate the .223 Remington cartridge, but a firearm with a .223 Remington chamber cannot accommodate the 5.56x45 cartridge.
A shotgun is a firearm. A revolver is a firearm. A pistol is a firearm. A rifle is a firearm. If you want even more specific -- A Remington 1187 is a firearm (shotgun). A Smith and Wesson 686 is a firearm (revolver). A Sig Sauer P226 is a firearm (pistol). A Colt 6920 is a firearm (rifle).
.223 Remington can be cycled in a 5.56x45 rifle; 5.56x45 should not be cycled in a .223 Remington firearm.
I don't see dbl in Remington, if you mean the dbl in general when when referring to a Remington firearm that's double as in double barrel shotgun, derringer, etc.
Remington never made a model 84 anything, unless that's a typewriter or firetruck or something other then a firearm.
That is too vague to answer. It depends on exactly which variation it is and what kind of condition it is in.
Not without endangering yourself and anyone else in the area. Stay with ammunition designed for the firearm you are shooting.
That is a statement, not a question. WikiAnswers is for questions. Please ask a question.
Google Remington scoremaster model 511. Several websites have information on this .22 firearm.
The best place to get information on the Remington 870 tactical rifle is on the Remington website. Another place to check is firearm forum where any questions or information can be shared through peers.