Take a some ferric chloride and stick a cleaned and de-varnished ten penny nail in it. Watch it start etching straight away and dissolve. You think one iron compound wouldn't bother to attack, but apparently the chlorine likes to be shared. And any little splatter of ferric chloride on iron or steel that is left to dry in an even remotely humid environment results a few weeks, if not days (depending on the humidity) later in a big knotty deep rust barnacle, heavily pitting the steel underneath. Definitely no go.
I'd guess the ammonium persulphate has a good chance of doing the same thing, but don't know from personal experience. The last time I was etching my own circuit boards was about thirty years ago, and then we had replaced ferric chloride with a mixture of dilute solutions of sulfuric acid and hydrogen peroxide. The peroxide cause rapid buble formation that kept scrubbing the copper so you didn't get the underetched zones that ferric chloride can leave.
The name, Hoppe's No. 9 came from the fact it had 9 ingredients originally. Last time I looked at the MSDS, it was down to 5. So, more than just the nitrobenzene (something archers once used to speed up development of callouses on their string fingers) were removed from it. I read the original formula somewhere once, with all 9 original ingredients included. I've forgotten where, but it seems to me there was a mercuric compound, as well, probably for amalgamating lead fouling.
The Hoppe's Elite is water soluble and safe. If you want something that is easy to get hold of that works about as well as the current #9, make up some Ed's Red. Automatic transmission fluid, deodorized K1 kerosene, mineral spirits, and acetone all in equal portions. The ATF and acetone alone is also a good penetrating oil. Your best bet it dribble a little down the bore while it is still warm at the range, plug the ends and head home. Getting the carbon while it's still soft makes it come out much more easily.
Finally, talk your gun store owner into importing some Boretech Eliminator, a genuinely superior general purpose cleaner. I also squirt it down the bore at the range and plug the ends with neoprene stoppers for the ride home. Gun is pretty much clean after I get there and wet patch it to clear out the bulk of the crud and to check for any remaining copper. I let that sit for ten and run a dry patch. No brushing, no muss, no fuss.
I'd guess the ammonium persulphate has a good chance of doing the same thing, but don't know from personal experience. The last time I was etching my own circuit boards was about thirty years ago, and then we had replaced ferric chloride with a mixture of dilute solutions of sulfuric acid and hydrogen peroxide. The peroxide cause rapid buble formation that kept scrubbing the copper so you didn't get the underetched zones that ferric chloride can leave.
The name, Hoppe's No. 9 came from the fact it had 9 ingredients originally. Last time I looked at the MSDS, it was down to 5. So, more than just the nitrobenzene (something archers once used to speed up development of callouses on their string fingers) were removed from it. I read the original formula somewhere once, with all 9 original ingredients included. I've forgotten where, but it seems to me there was a mercuric compound, as well, probably for amalgamating lead fouling.
The Hoppe's Elite is water soluble and safe. If you want something that is easy to get hold of that works about as well as the current #9, make up some Ed's Red. Automatic transmission fluid, deodorized K1 kerosene, mineral spirits, and acetone all in equal portions. The ATF and acetone alone is also a good penetrating oil. Your best bet it dribble a little down the bore while it is still warm at the range, plug the ends and head home. Getting the carbon while it's still soft makes it come out much more easily.
Finally, talk your gun store owner into importing some Boretech Eliminator, a genuinely superior general purpose cleaner. I also squirt it down the bore at the range and plug the ends with neoprene stoppers for the ride home. Gun is pretty much clean after I get there and wet patch it to clear out the bulk of the crud and to check for any remaining copper. I let that sit for ten and run a dry patch. No brushing, no muss, no fuss.