Ok, I just nabbed me an Azodin Kaos pump, and I noticed it has dual ball detents.
Why is this special?
Because they actually hold a .62 cal ball in place without the double feeding issue.
I can now use my .62 cal insert and not double feed. (most .68 cal breeches have enough room for 2 .62's to double feed)
Now I can use the 3 cases of 6 yr old .62 nelson paint I have.
(doesn't break in a pump, unless it double feeds)