Question about Steyr M95 built in about 1917

[thojohnson304]

My elder brother died last month and I received a Steyr M95 straight pull
bolt action from the estate.
It has some interesting modifications. First, a hole has been milled in the
barrel just in front of the action. Second, the bolt does not have a hole
for a firing pin to come out of the bolt face when the trigger is pulled.

The action works and cocks and "fires" when the trigger is pulled.

So any ideas who and when and why someone modified the rifle this way?

Also, any ideas where I could get a new or used bolt and barrel?

Thanks!

TJ