Hi scooby, what makes doing the perfect sight replacement is that the edges of the keyway were staked. That narrows the top of the keyway slot. On some of my front sight 1860s I would file away the coined staked edges of the keyway. If I had the ability to stake the front sight in, I would do so. The Pietta 1860 has a deeper keyway than the Uberti. The sight that failed to hold was pushed in with an arbor press with JB Weld in the keyway. Since the sight isn't staked in, the only force holding the sight in is the compression of the slightly larger width brass insert compared to the keyway and JB Weld adhesion.
An internet search shows that JB Weld isn't a reliable adhesive for sights. Hopefully the Loctite 380 will work better.
Regards,
Richard