Gwinny da Pooh, I have found problems with cheapie berdan corrosive ammo prior to 1955(especially .303 Br) and some current Russian target ammo for the TOZ 36/49 pistol. Even some .22 RF can give problems, but it can be very accurate indeed.
I have found SWEETS 7.62(ammonia based solvent) and Hoppes No9 good, but the best is hot soapy water funnelled down the barrel ! It is cheap/effective to get rid of the hygroscopic salts and dries easily -then you remove the metal fouling with the usual solvent. Brill !
Many WW2 abnd WW2 rifle barrels were ruined by lack of field cleaning with consequent loss of accuracy, feeding problems and heavy felt recoil.The mercuric priming also can weaken brass for reloading purposes too, so care is needed.
The wiser Russians and Chinese lined their barrels with hard chrome - resulting in less fouling and far less clearing, even with their corrosive ammo. The famous SKS S/A 7.62X39mm carbine and Moisant-Nagant B/A rifle 7.62X56mm [R =rimmed] are but two I have used with this feature.
Neat eh ?