You could experiment with bedding the tip of the forend, lightweight sporters often had contact close to the end of the wood to stabilize the thin barrel.
I would get some small post it notes and loosen the action screws, tear off a thickness to just fit under the barrel with the action loose, then tighten and check that the paper is wedged tight. Then go shoot and see if it helps.
Temporary, as the barrel will settle into the paper and loosen soon, and paper is subject to moisture, but might tell you a direction.
A permanent fix would be an epoxy pad under the barrel.
No change and you're back to the barrel, or barrel receiver fit.
Are you fitted to the c-ring or the front of the receiver? Did you square up or check the fit on the c-ring?
I squared the c-ring and receiver, ended up with 80%+ contact on the c-ring showing on dykem, and a hairsbreath of daylight showing between the receiver and barrel shoulder on my 98 in 6.5x 55 AI. It shoots consistently sub moa, but it also has a big ass heavy barrel.