I've posted this here many times before, but for new folks who may have one of these guns, or are thinking about buying one, and want to know how to check them in a store for correct throats, I'll post this again-

The older Pinned guns with the N prefix had oversized throats and were not the best shooters. Some with a N prefix did have the correct throats, but they are the exception to the rule, as most will be .455"-.458" in diameter. Any 25-5 with the ABC 1234 serial system will have the correct throats in it and should be a great shooter (as long as it has been taken care of, of course)

To check the throats, take a jacketed bullet (use a jacketed bullet and not lead, since lead is normally lubed and sticky in of its own nature anyway, which can give a false impression that they are fitting correctly) with you (Hornady 300 gr XTP's work best because they are longer and are .452" in diameter) and drop it into the chamber from the rear. If it falls right on through, the throats are too large ( normally .455" or bigger) to give very good accuracy with standard .45 Colt bullets running .451"- .452".

If it hangs up briefly in the throat, then falls on out, you are looking at throats that will be in the area of .453"- .454", and will work with some of the larger bullets out like the factory Win, and Rem swaged lead bullets.
If it hangs up in the throat, but can be pushed on through using a pencil or pen, and using only finger pressure to do so, you have a gun that will potentially be very accurate and what you are looking for in a shooter.

If you get one that has large throats, the Winchester and Remington swaged lead bullets that they sell at places like Cabela's will usually improve their accuracy with standard loads by quite a bit since they run .456" and .455" respectively, and have hollow bases to help the bullets obturate and fill the throats which in turn help align them with the bore before entering the forcing cone.