lost accuracy after barrel polishing

What all did you do to regain accuracy I just got an avenger and right out of the box it was shooting GREAT I own several guns but this is first air gun so I pulled the barrel off and cleaned it now it won't shoot to save my life and I've put over 6 to 700 pellets through it since cleaning and I used a bore snake to clean and my barrel and it never had a crown I have tried polishing it lightly with jeweler's rouge maybe 10 total strokes with rouge and I have 375 through it since the polish no change 
 
I rebuilt 2 rifles for a guy that would shoot 50 in the morning and 50 in the evening and measured and documented all. He was a little concerned that the ammo over years had degraded. He used a pull through after every session. When i pulled the barrel and inspected it, the crown had NO RIFLING for about 4 mm. He had worn it completely away by using a pull through. Keep in mind he had documented 104,000 rounds through it, but the point is there for less shots. Weedeater string will likely speed that up dramatically. I'm fortunate that the rifles we shoot most have good breech access or easily removable barrels for cleaning. I really don't like cleaning from the muzzle in any way unless absolutely necessary at that moment.

Polishing from the muzzle would be a HUGE no no.

I'm probably paranoid but air rifle barrels are soft compared to pb barrels. Pellets are unlikely to EVER wear out a barrel but abrasives of any kind need to be used carefully. I prefer to hit what I aim at.

Bob
 
I have used heavy mono fishing line for many years as a pull thru for my airgun barrels. Never recomend using a metal rod even with protectors. You big bore guys would be an exception as the bore is large enough for a good protector. For those instances where the breech cannot be easily accessed, simply double over the fishing line and slip it thru a drinking straw for those having moderators to get it into the bore, push until it comes out the breech. Slip another fishing line thru that loop along with your patches and now you can pull back and forth from muzzle to breech and do a thorough cleaning!! You never have to worry about damage to crown or breech. 

I also use beeswax spray as a lube for my pellets, leaves a dry slightly waxy coat on the pellet, is self cleaning in the barrel, meaning that therevis no buildup and a patch sprayed with beeswax will clean and disolve any residue left in the barrel. Just a couple pulls with a beeswax coated patch and barrel is clean. Also a natural rust protector and no nasty odor.