If the T-ring is simply tight, the safest first step is to improve grip rather than modify the metal. Try rubber gloves or a rubber strap/band wrench so you can apply even pressure around the ring without squeezing too hard.

If lubrication is needed, use only a very small amount of anti-seize compound on the mating threads/surfaces—just a light film applied with a fingertip. Use as little as possible so it doesn’t migrate into the camera. Once attached, it should spread thinly on its own.

Avoid filing the T-ring unless you are certain there is a specific burr or defect, since removing material can worsen fit or create the very metal debris you’re trying to avoid. In general, mechanical grip and a tiny amount of appropriate anti-seize are safer than aggressive modification or heavier lubricants.