I've been looking for a new build, and with ammo prices the way they are, I tend to shoot .22LR the most. Has anyone ever done a .22LR bumpsaw build? Would love to hear about your experience.

There was an extensive write-up on doing one that was reliable in Shotgun News a few years back.
Basically it was all slicked up and worked perfect.
I can not recall all the things the writer did but he was a perfectionist.
On Youtube it looks like it does take some different technique that some can and some can't do naturally right off the bat.
One clip shows a guy who had problems doing it having his little sister do it with no problem on video.

IIRC, it's easier starting with a light weight platform like the S&W M&P 15-22, the low recoil makes it difficult with standard weight parts.  You will also need a short reset trigger.

slide fire makes a .22 bump kit