hm...
i will look into this. how does a drip tip fit?
EDIT...
OK. A drip tip should fit fine.
I pulled a dummy cart off a brand new JOYE 510 atty, and it fits rather loosely in both of the SE atties I have on hand (conversely, it fits very SNUG in the JOYE atty).
The solution, is 901 carts. Either DSE 901, or RN 4075 should do fine. Both are available from ≈LF.com. The 901 atty has a slightly larger ID than the 510.
I know the DSE 901 flat tip carts are black, and my preferred cart (i used to sand them down, a little skinnier, back when I used a 510 atty).
and the round ones are filter color. I think, if memory serves, they hold ≈1-2 drops less than a 510 cart.
Hope that helps.
PM me for further details.
Thanks,
Ty