I take a PL259 adapter to BNC or N and move on myself. I have not used a pl259 since jsertrola days. I haven't used on in theshack since about 1974. Yes I used to tin the shield so solder would flow easier. The trick is a lot of heat and move fast.
I never tin the braid, that makes it too difficult to get the connector on. Like Frank says:
"use a lot of heat and move quickly". this is a good app for one of those big, manly
Weller 240 / 325w big soldering guns. If you try to use a little girlie soldering iron you just cant get emough heat to make the solder flow.
I hate to see those wimpy S.O.B.'s who are afraid to solder the braid on their pl-259s. This is just asking for intermittant problems when you are running high powered equipment.
The Slab Bacon
I use one of these little pen torch things(crack torch?), load some slobber into one hole, then hit the connector imediately with a blast of air. (The canned keyboard cleaner) Do the remaining 3 holes the same way. The air cools the connector off fast and keeps the heat from ruining the center insulation. Takes practice to control the heat but it works like a charm.