WD40 displaces water. Black powder fouling is very water soluble. WD40 is to make sure there is no water left. Once in a while use a brush on revolver and shotgun with some bore cleaner. Never saw a need after shooting patched round balls in my rifle. Just water and WD40. Before I load one I clean the bore with a little rubbing alcohol.

Regular firearms get clp. After a few hundred rounds I use sweets 7.62 to remove copper. Have to be careful with sweets. If you dont get it all cleaned off after you remove the copper from your bore it will corrode your firearm. I remove the stock bolt and trigger assembly to use sweets. Less stuff to remove solvent from.

JB bore paste will remove lead. Dont want to use it very often either. Best to only use either of those products when your you groups start to open up.

At least thats what I think.

^ right, the WD in WD 40 stands for water displacement. WD 40 is not water based, it is a petroleum based product developed for the rocket or plane industries I believe back in the 50’s or 60’s.

The Specialist WD-40 I mentioned was not developed in the 50s.

A group tman gun oil test would certainly be interesting.

you should also never clean your rifle from muzzle to chamber as you run the risk of damaging the rifling

Interesting to read through the comments above. I am not a competition shoot, rather a hobbyist / hunter and have been in the fall/spring goods industry for about 25 years. During that time, I've worked with 100's of manufactures of ammo, firearms, and various cleaners. I deal with Military, LEO, competition shooters and so on. Personally, I shoot about 200-500 rounds a month. Years past much more than that. Here is what I learned from the industry about cleaning the bore:
1. Three different considerations - Black Powder, smokeless shooting lead or jacketed bullets, and smokeless shooting monolithic copper (Barnes TSX,...)

Black powder - use products specific to black powder and clean after each use.

All Others - Do NOT clean until the rifle shows signs of fouling and your POI is drifting off

No need for any solvents with modern smokeless powders. Windex changed its formulation a couple years ago and has less alcohol/ ammonia than previously, but is still good to use. Any widow cleaner that evaporates quickly is good. That will remove the residue and carbon. A couple passes with a brush will remove the lead residue. A very light application of a quality CLP will prevent rust if its going to sit. Your goal is NOT to remove all the lead that has filled the many minor imperfections in your bore. Most rifles if broken in properly will achieve improved accuracy after 50-100 rounds. That is because the lead has filled the voids left from the tooling process. Often people that "over clean" notice that their rifle shoots better after 5 or so rounds after cleaning

Copper monolithic bullets - if your POI is slightly drifting off, first just clean with window cleaner and test. If and ONLY if you have copper fouling that has impacted your accuracy, then proceed to perform a copper de-fouling . I've had great success with DCR-10 and wipe-out. I have a cheap browning A-bolt in 270win that has maybe 600 or so copper rounds through it. Never been cleaned yet and is a tack driver out at 700+ meters. My 270WSM needed to have the copper removed at about 500 rounds. It varies but its more harmful to over clean.

Best advise I read so far is this:

Over cleaning is a real affliction. Some folks just love to tinker. Buffalo Bill and Billy Dixon used what they had and just kept piling them up. And Jim Bridger surely didn’t unload and clean his Hawken every night.

Having worked in the firearms industry for 32 years, and seeing guns coming in for "repair" because the owner used WD40 on the fire control and it was gummed to the point it no longer functioned I would not recommend.

You can use whatever you'd like, just passing along.

You can probably leave a gun loaded with black powder forever. I have left one loaded for several months. Shot fine. Its the fouling that rusts them. Substitutes are a different story. Guys like Bridger cleaned their guns after shooting them. With water.

P.S. Rubbing alcohol takes WD40 right off. I only use it in black powder guns after cleaning the fouling with water. Dry everything and use gun oil probably just as good. WD40 never gummed up mine. I also dont use it on modern firearms.

Not cleaning wont work well here.
They go outside and there is weather.

I didn't check before I said WD40 was water based, so sorry about that. I have been around a machine shop with water based spray mist for the machines and assumed WD 40 was the same because years ago I had it freeze up in a semi-auto shotgun. So, I guess that is why it worked for a starting fluid in a 2 stroke. But, in my opinion it sucks for a lube or protectant on a firearm that is out in the weather.