UR website[0] seems to suggest +- 10N (a kilo resting on your neck) with their stock implementation. I imagine you're going to want something better than that.
What Force/Torque sensor do you use? Some of them are temperature sensitive and require a good warm-up period before they can be used to achieve good performance.
[0]https://www.universal-robots.com/how-tos-and-faqs/how-to/ur-...