I think I have memtioned this to Porwath in the past but if you guys want to take a scientific approach you could run a test I have run in the past. It takes all the guess work out when the goal is to find what product disolves copper the best.
First for me I see no reason what so ever to use cheimicals that produce extremely nouxious gases and odors such as ammonia. Back 25-30 yrs ago you had to and it worked and still does well but had to be careful with ventilation and time left in bore and flushing/neutralizing all product from bore. Butch's Boreshine, Sweets 7.62, and hombrews ruled the day. These days there are choices that will not hurt the bore if left in and are not goig to damage your lungs and sinus and eye tissue.
So here the test I did. I choose to use a rather expensive medium as they were pure copper and very consistent weight.
I used .270 gs customs bullets weighed them to make sure they were with 0.01 grain. Then i setup shot glasses.
I picked up or had sent to me a smaple of every barrel copper solvent produce I could get.
Put solvent in each glass enough to completely submerge the bullet then dropped in the bullet and started the clock. Checked 30 min, then 1 hr then every hour for 4 hours. Then allowed them to sit to 8 hoirs checked again at the 16 hour point and finally 24 hrs. I think I allowed it to go a bit further but collected my offical data @ 24 hr.
Each time I removed them from the solvents I wiped them down throughly and rinsed in distilled water dried and weighed. Also took pictures to show changes in surface as the camme outut a and aafteer drried ppost weighing.
I think people would fine results of similar testing to be of interest and worth while. You could possibly use a piece of copper wire stripped from electrical insulation. Say 8 g. I choose the bullet even with the cost becuase it gave surface area equal to a bore for solvents to work and meausable rsults would be easy as well as the visual effects could easily be captured witha cammera. One I wanted to use was Barnes bullet as they are made ouut of guilding metal vs pure copperr just to see the difference in effect. It would aattack. The coppper which would then cause other metals to release from the bullet body. Stilll thought it would be innterestinng but nnever did it.
I can tell you those with super high ammonia worked well but everyone knows that and the reasons for not using it if there are equal or superior products without those drawbacks,
Honestly, where I tested 10-12 products IIRC; based on what is popular here, you could do 2-4 products. You could do Sweets (for an ammonia based produce), Bore Tech CU+2, and KG 12 Big Bore. For those intrested you could also add in wipeout and wipeout + accelator. But for those foam ones you have to add it and let it setttle to liquid which does not take too long so the copper will be submerged.
The reasons for the long soak times are so we can easily see the changes. In a bore we are dealing with minute amounts with lots of surface area to total mass and even dislodging it to allow it to be pushed to witha patch can be enough although not ideal. Point being its upscaled to give easily readabe results in amounts we can relate to.
You can easily use a good quailty powder scale that has a accuracy to 0.1 but helpful if rsolution is 0.01.
I had used a very $$$ lab scale tha could go to 0.002 grain or more correctly 0.150 miligrams accuracy with a resolution of 0.001 mg. Picked it up from UVA science lab, for pennys on the dollar, when they were getting new equipment in to replace it. Royal PITA to setup for it to work to that level. Needs very clean electricity, no EMI (no florescent or any electric motorrs running), concrete table for no vibrations, no moving air currents, and it has a hood over the scale. Like I said PITA. It was easier to just drop a zeros worth so it could be reproduced.