MarcelB, several years ago, I bought a converted Siamese Mauser. It is in 45/70.
The sights on the rifle were put in place with JB weld. I was going to remove the bridge mounted "peep" and fore sight and replace them with either a low power scope or screw on sights.
Before trying to get the sights off, I talked to the old fellow that attached the home made sights (very nice) and found out he knew his stuff. He lightly, roughed up the area first with a fine punch and cleaned the area well with a degreaser. He then applied the JB Weld and the sights which had been treated similarly.
I took the rifle out with some hand loads, with 500grn RN over 57grns of H4895. This load is a bruiser, for me at any rate. I put it in a lead sled and fired 60 quick rounds through it. Not something that is normal. The sights worked wonderfully. They were lined up perfectly and only needed a bit of elevation adjustment. I did a similar test with 405 grn cast bullets and 305 grn jacketed HPs. Over all I would say at least 500 rounds through the rifle since its purchase. The sights are still solid after 10 years of handling and storage. Its been used under harsh northern climates and in HOT okanagan weather.
My eyes aren't what they used to be so I don't use the rifle much any more. I just took it out to look at it and nothing has changed.
Understand, I don't condone "gluing", it is a real pia to remove if you want to get rid of the sight. It is a great way to settle down errant bases that on some rifles just seem to come loose. It is also a great way for an at home do it yourself type that doesn't have d&t capabilities or the money to get it done to do the job. Just understand, if you screw up, it's permanent. Mind you the same thing goes for a poor d&t job.