Reliabilty
Most problems are due to feeding and extraction.
So I and others concern ourselves with Chambers, and Extraction.
Shotguns:
Plastic hulls leave a dry, gritty, residue that builds up in chambers. Add the poorer quality of shell bases not being made of brass we see of more recent manufacture, instead of inferior metals , inferior to cheap beer cans even, further adding being out of spec...
Shotshell has to feed into chamber - everytime, Shotshell upon firing, has to extract everytime, no matter the action type.
Paper hull shotshells with the wax coating - did NOT leave a dry gritty coating as do the plastic...some plastic is worse than others as well.
Firearms in General :
It has been said too many folks spend too much time cleaning what is not important, and NOT cleaning what is.
One may have the most pristine bore, trigger group, the stock clean, waxed, protected, if equipped with attachements, these are clean, fresh batteries in any lights or optical sights.
If the shell does not go into the chamber, then extract, then respeat - else:
Here lies _____ Firearm did not work, but the bore was immaculate
It is suggested one shoot a minimum numbers of rounds of EACH Carry/ Duty ammo and in Magazines and Speedloaders.
While doing so one is to inspect and take note of what that particular weapon with those ammo choices with those particular mags/ speedloaders leaves behind in regard to residue, debris, and lubrication needs. What is required to keep that gun reliable.
Serious situations:
Bad breath distance...
Plastic fouling near the muzzle/ screw in choke not going to mean a darn thing, chamber dirty, extraction dirty is.
Revolvers- residue under the extractor, cylinder bind, and /or not being able to open cylinder quickly to eject spent shells and get a speedloader to reload, a lot more serious that the finish being perfect and the stocks being clean.
Semis - Dry clean mags, chamber clean, extraction working, will keep you alive moreso than the fact you cleaned the residue out of the front strap checkering, the firing residue is clean from exterior of slide near muzzle, and there is no nelphs in the torx grip screws.
Gun gotta run with ammo everytime. Chamber, extraction are what I concern myself with.
One can take tips HSMITH , Dave, myself have shared to make this easier and faster, or one can spent lots of time , spend lots of money for fancy tools and such. That is up to you.
Does the darn gun chamber and extract, does the gun run?