The striker protrusion is set by the overall length of the bolt-head . (Given "consistent" striker dimensions)
Furthermore, when the action is closed for firing, the bolt-head is set to transfer ALL of the thrust od the cartridge head DIRECTLY to the front face of the bolt body, and thus to the locking surfaces. The bolt-head THREAD should play NO part in transferring this thrust.
This is why bolt-heads are "paired" to their bodies in the final assembly. If the bolt-head "under-turns", the bolt CANNOT be assembled to the body. Get another one out of the parts tray.
If the bolt-head OVERTURNS more than a few degrees, The threads will start being battered at every shot and headspace will thus start to grow.
Lee Enfields are NOT "shake and bake" rifles.
There are copies of the "official word" on this matter out there on these Inter-Tubes.
How many variables can dance on a Km7 bulllet meplat?