Assistance request on Savage/Stevens No.4 Mk 1*, please

[Alan de Enfield]

The B stamp certainly (to me) looks like the Long Branch (L superimposed over the B) marking. There are many stories about Savage supplying parts to LB.
Are there any LB markings on any other components (barrel) ?

The original bolt has been 'lost' and a civilian has just 'put in a bolt to fill the hole' If it had been fitted by a military armourer it would have been numbered to match the body.

The reason that Lee Enfield bolts are numbered to the rifle is that they are not interchangable, each bolt is 'fitted' (work done) to each individual rifle. You should not fire it until you have checked out that both the headspace is correct and you have proper contact on all four locking lugs (2 on the bolt and 2 on the body)