As SCLoyalist noted, your combination measurement of .526" in a .532" groove diameter shows at least .003" per side, TOO thin. A .495" ball and .022" = .539" will only give a .0035" compression in the grooves but will give a seal for any powder charge you will ever use.
The .010" undersized ball is not a good choice for deep, rounded bottom grooves.
Brother Taylor does better than quite well (hard to beat) using a .495" ball and .022" ticking or denim patch in his Rice .50 with rounded grooves.
As a matter of fact, we were out playing yesterday at the range, from 25yards and out to 100 yards. A fun day. I shot my .32 squirrel rifle, .58 Musketoon and my 14 bore rifle - Neither of us had to wipe the bores during the 4 hours of shooting. I did hav eto put down the .59 and .69 when the barrels got hot and heat mirage made the target's bullseye bouncy.
The rifles shot quite cleanly and when cleaned after getting home changed the water for each. The breeches were dunked into a 3 pound coffee can of water and flushed water into and out of the bores - single patch to clean, 3 to 4 patches to dry. copiously sprayed WD40 into the bores, blasted the excess WD40 out the nipple seats on the .58 and .69, as well as out the vent of the .32 then used that WD40 patch to wipe down the outside, then replaced the barrels in their stocks. Locks cleaned in water with toothbrush, then blown off with compressed air, then sprayed liberally with WD40, wiped and blew off the excess, then replaced in their stocks.
For the last targets we shot, Taylor put up a couple 2" round black bulleye's at 25 yards. I kept this offhand target for measuring, shot with my 14 bore rifle using 3 drams (82gr. 2F) and a 15 bore ball (.677") with .030" patch (12 ounce denim). I managed to get all 5 making a hole that measured 1.458" outside to outside & .781" centre to centre after subtracting the .677" ball's diameter. It was an extra good target for me. All fired patches are reusable if re-lubed, BTW.
The combination I used measures .677" + .030" + .030" = .737". The groove diameter of that barrel is .690" + .012" + .012" = .714". Thus, I have .737" - .714" = .023" divided by 2 = .0115" compression in the bottoms of the grooves - which makes for a perfect seal.
Bore is the tops of the lands to the tops of the lands. Groove diameter is bottom of the groove to the bottom of the groove opposite, the largest size and the size that must be beaten to get a seal.
I should also note here, I was shooting WW alloy round balls from a Tanner mould, not pure or dead soft lead. The quite hard lead is why I used the undersized balls. When using pure lead, I use a .684" ball and those same patches.
I changed the water for each gun and the container's water was practically clear, only slightly grayish. That included cleaning the locks in the same water as the barrel. The only buildup was in the breech area - which is why I use such snug combinations - NO POWDER BUILDUP in the bore.