What do people recommend for cleaning the bore of PCP and Break Barrel rifles?

If it is dirty the gun scrubber works well, after cleaning be sure to pull a dry patch and follow up with an oily patch to protect your barrel. Going forward consider lubing your pellets which will make barrel cleaning much easier down the road. For springers my choice is a beeswax furniture polish as a pellet lube. Wont cause any harm to anything on your gun, all natural, smells good, wont buildup, has improved accuracy on every rifle I have used it on. 
 
Is use Simple Green cleaner. Works great won't hurt anything. .Ballistol is mineral oil based and not as good as Simple Green. Ballistol is great for wiping down the gun, good for metal,rubber,and wood. For bad barrels you can use nylon or brass brush. Don't use a brass brush on vintage Crosman barrels with brass barrels. Steel is ok. 

Tom Gaylord polishes some barrels with brass brush and polishing compound. Tom is a noted airgun writer if you are not familiar with him.
 
Elh0102, do you think using Hoppes bore cleaner solvent is a good idea in a airgun? I know it works great in firearms, but seeing it was for specifically firearms, I was unsure of using it in airguns.

I wouldn't recommend it, although I don't know that it presents any risk. My question would be its compatibility with O rings. I know the other products cause no problems. The only fouling in an air rifle barrel is light leading, and it just doesn't take much to remove it. This may be changing as we see ever-increasing velocities in the high power market.

I should add, I've had a few otherwise very good shooting barrels, that were prone to frequent lead fouling, probably due to slightly sloppy machine work, usually around the chamber leade or choke. Although it's only lead, such surfaces can be a chore to clean. I've usually gotten them clean with a nylon or bronze brush and a good scrubbing.
 
I use patchworm and ballistol. Hoppes is not a good cleaner for airguns. It hurts seals. Simple green is OK too but not my favorite. It won't hurt anything though. Patch worm works really well. If your barrel is super leaded a brass or nylon brush is fine but don't use the cheap ones with a steel base. You can also use a string with a loop at the end to pull patches through. Just make sure its tight against the bore.
 
run some dry patches occasionally through a pellet barrel, scrubbing it with chemicals just ruins accuracy generally .. a slug barrel may lead up though depending, you may have to scrub those just like a regular gun .. but pellet barrels i say no leave it alone before you screw it up .. my 25 is 10 years old and it shoots better now than it ever has and never been scrubbed .. just dry patched once a tin or so ... a springer is a whole other ballgame lol, you may have to 'compound' the barrel to smooth it out depending on what cheeze level of springer you got lol .. after its where you want it though .. dry patch only ...
 
DON'T use a solvent. You want a certain amount of "seasoning" (leading the barrel). That's part of what the break-in period is about. Use a pull-through type or bore snake (without the wire brushes). Always run a final dry patch through to make sure it's clean & then a LIGHTLY oiled patch to preserve metal. Ballistol works great but so does a lot of other stuff already mentioned. Don't over think it. It ain't "Rocket Surgery" (hybrid of Rocket science & Brain surgery).

NOTE: You can make your own pull-through using weed whacker line & a small round single hole copper crimp on the end. I've been doing it for years. 
16415890662591865297104230649103.1641589115.jpg

 
I believe it's true that most air rifle barrels shoot better with some lead and graphite in the barrel. The break in process does that, but it also fire laps the barrel. Most production barrels are cleaned and lubed in some manner after machining, but a true lapping process is generally a custom maker feature. Since making and properly using a lead lapping tool is beyond the capability of most of us, the initial pellets through the barrel is a sort of mild lapping, which helps finish the lands and grooves, removing some of the tiny burrs that remain from machining. If the barrel is cut or button rifled, the condition of the tooling and quality of the operator means a lot. Some are great and need little break in, others are so bad that the lapping provided by shooting pellets will never fix it. Those make great tomato stakes.