Hoppe's #9 solvent
As you can probably imagine, as a result of serving as a police armorer, I have considerable first hand experience (40+ years worth) with the use of Hoppe's #9, both as a user and a witness.
First of all, the Hoppe's web site does confirm that the #9 solvent contains ammonia, so there is no dispute about that. Whether or not it qualifies as one of the "harsh chemicals" as S&W puts it in the manual, that is to be avoided is personal choice. Most dedicated #9 users are adamant about the fact that in their experience, the product has caused no harm to their firearms in terms of finish or otherwise. I think this is because most people are using the product according to the label directions, which state that residue and excess solvent should be wiped off of the metal surfaces after cleaning has been completed.
Although I have used Hoppe's products over the years, including the #9 solvent, I've never used any product containing ammoniated solvents on nickel because the ammonia can damage the nickel finish, (reason below) and because there are so many other products that do not contain ammonia that work just as well, if not better.
In terms of eyewitness accounts as to damage....during my work as one of my local department's armorers, I saw many examples of damage from the ammonia ingredients in this product, on both S&W and Colt nickel plated revolvers. The damage usually manifested itself by causing the areas affected on the surface of the gun to turn "cloudy", and have a dull appearance. Sometimes the damage could be mitigated by careful polishing, sometimes not, depending on the severity of the damage. This dulling, or cloudiness damage of the finish did not ocurr quickly (exception below), but was caused by years of misuse of the product. I have no first hand knowledge of Hoppe's #9 harming bluing.
My other experience is still quite painful, even though it happened more than 30 years ago to one of my fellow officers, and a member of our pistol team. In an attempt to clean the cylinder of his beautiful nickel model 27, the officer in question placed the cylinder assembly down into a wide mouth Mason jar containing enough of the #9 to cover the cylinder portion with the liquid. The assembly was left in the Hoppe's overnight. The next day, when he removed the assembly from the jar, the cylinder came out, but the plating that was formerly on the cylinder was left in pieces inside the jar.
The damage was remedied by sending the gun back to S&W for re-finishing. Obviously, this is an unusual circumstance, and was clearly contrary to the manufacturer's directions printed right on the bottle, but an important lesson was taught nontheless.
This post is not meant as an indictment of this particular product per se, but as a warning to use Hoppe's #9, and all gun cleaning/maintenance products according the label directions.
