M91 Internal Threaded Barrel?

Hello,

I a few years ago, I purchased a Mosin Nagant M91 Puolustuslaitos stamped 1895r in Arizona. The rifle was owned by the sellers father who passed away. The son did not know much about rifles and just wanted it gone. When i met him to check out the rifle, i looked down the barrel and noticed that it had been internally threaded. I had no idea why someone would threat the barrel internally. The threads were made fairly recently as there were still metal shavings coming out of the bore and barrel. I knew any real value had already been ruined but i still bought the rifle anyway.
My question is, has anyone heard of internal threading on a military surplus rifle and what purpose would that be for? Internal suppressor? Plugging up the end of the barrel to clean it? Some other strange reason?

Someone posted one here a while back that had been made into a lamp. Including internal threading for the lamp hardware.

Find a drill bit that is just barely too large to fit in the muzzle. Drill out the threads. A large percentage of Finnish M91 rifles are counterbored anyway.

The drill bit will center itself as it chases down the bore. After you have finished, you will have reclaimed it for a shooter if you so wish.

Yep, lamp. Has the butt been cut?

Good lamp advice. Ill post some pictures a little later.

Doesnt look like any other modifications were made besides a small stock square cut repair.