Interesting rifle.
Here is my guess:
This looks like a Mauser built up in period to be similar to an African model.
The barrel, trigger guard and stocking are all Stogos style although the long forend I havent seen on a Stogos marked gun before but I am sure could be ordered that way.
The holes in the stock IMO are from mounting a torch (flashlight) on the side. Although the caliber and barrel length would preclude this gun from being used in thick bush, it would be an ideal rifle for shooting hyenas at night time with that light mounted to it. The bayonet would be useful if things got too close.
Then again, it could be a military match rifle pattern...