Lithgow No1 mk III* nose piece fitting?

[muffett.2008]

Your barrel is sitting too high in the forewood.
You need to ascertain why. Is the barrel clear of the channel except for the last 1.5 inches at the front? you should be able to slip a piece of paper under and run it along the channel.

Attachment 35844Attachment 35843
If not, you will need to deepen the channel,( the quickest way is with a sheet of coarse paper wrapped around a dowel) continually checking for clearence and nosecap fit.
If your forewood is new and unfitted, you will need to ensure the rear setup is correct first.
Without timber, fit your trigger housing to the action, ensure the spacer is in place. Measure the total depth of timber required at this point, allow an extra 1/16th for crush.
Now measure the depth of the cutout in the forewood, it's probably massive.
This needs to be corrected while also watching the fit of the draws and nosecap angle.
It's hard to describe, but the barrel angle is determined by the rear setup, you need to correct the rear, ensure the barrel lies flat with slight downforce in the channel, then line up the nosecap.
If this means removing timber from the front then so be it, but if set up correctly, it should require only minor adjustment of the topwood to get it to slip in.
Check the width of the forend in relation to the top front guard, this will determine if you sand the top or the bottom, ensure you maintain clearence on the top also.
Have fun.