Picked up a neglected '58 Remington (Traditions) with an extra cylinder for dirt cheap.
The reason is someone didn't decide to to a thorough cleaning and I can't get the nipples out of one of the cylinders.
Soaked in PB blaster for 48 hours and the crappy "wrenches " are stripping...
Other than an EZ out and ordering replacements,  is there a better wrench or technique  ?

Try lil out, lil in. Repeat.

Try Kroil

use a modified 4.5mm or 5mm socket in a drill press, while clamping the cylinder in place between wooden blocks... keep downward pressure on the drill press while you manually rotate the socket in the drill fixture by hand

Patience, patience, patience, and the old standbys of Lube, Vibration, and Heat.
50/50 mix of acetone and ATF. Let the cylinder soak in it. Better than any other penetrant, including Kroil.
Toss it in your tumbler or ultrasonic cleaner for a while every day.
With a pencil torch or soldering iron, heat up the area around the nipple.
Lather, rinse, repeat.
After multiple cycles, try to unscrew it as noted in posts above (fitted wrench, downward pressure while turning).
When it still doesn't move, repeat the above. I have spent months on a rusted nipple before it finally gave up.