If the inertia block swings freely and easily on it's pin and does not jam in the forward (blocking) position,,you can test the gun out for doubling problems with out the spring installed.
With out any spring installed at all, the inertia block has nothing to hold it back from doing it's job when the shot goes off, regardless of how little recoil is there.
With the action assembled off the stock, see at what angle the block will stay back and not fall forward to block the trigger on it's own. You'll need to know that info for when you do live fire later.
It usually takes quite a steep downward angle of the gun to drop the block forward on it's own weight.
Make sure when it is forward that it is indeed blocking movement of the trigger/sears in both selector positions.
Then with the stock on,,tip the gun down to engage the inertia block and see if you can (dry)fire it at all.
Do this in both selector positions.
If it does fire, the inertia block isn't working. The stock wood or something is interfering with it's movement.
If it works OK,,take it out for live fire. At a proper raised elevation to ensure the recoil block is not engaged, fire a few rounds and see if the gun doubles. It shouldn't with no spring tension at all for the inertia block to overcome, if that is in fact what the problem is.
You are just taking the question of spring tension out of the mix and seeing if the inertia block itself is working correctly.
