It is not a safety issue. Worn muzzles due to rubbing with steel cleaning rods is very common with older military rifles. Instead of rebarreling, which was expensive, counter boring was cheap, gave the rifle a little more time till it needed to be rebuilt, and things like this were done in times when "get it out the door" was the highest priority.
Incidentally, your rifle was not, nor was it ever intended to be a target rifle. Nor where the men to whom it was issued to, trained to any standard of marksmanship. There simply was not time. American's absolutely forget the attrition of men during a major war. Around 1943 American was experiencing 60,000 causalities a month. That translates to 20,000 dead and 40,000 in various states of disassembly. The Russians had it worse, this was to show how effective the German advance was.
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Ukrainian commander reveals true scale of losses – and pays the price
17 Mar 2023 The Telegraph
Battalion commander says all 500 of the original soldiers in his unit have been either killed or injured as he calls for better training
Kupol told the Washington Post this week that the Ukrainian army training was often poor and that some of the rookie replacements didn’t know how to throw a hand grenade or fire a rifle. Others had abandoned their positions shortly after arriving at the front line, he said
“I get 100 new soldiers,” he said. “They don’t give me any time to prepare them. They say, ‘Take them into the battle.’ They just drop everything and run. That’s it. Do you understand why? Because the soldier doesn’t shoot. I ask him why, and he says, ‘I’m afraid of the sound of the shot.’ And for some reason, he has never thrown a grenade. …Kupol said what was left of his unit was also facing ammunition shortages. “You’re on the front line,” he said. “They’re coming toward you, and there’s nothing to shoot with.
Men are arriving at the front not knowing how to shoot their weapons, or knowing how to use other weapons. And this is not the first time this has happened. It happens in every major war, including the American experience during WW2, These manpower shortages start around year two, because by then the pre war Regular Army guys are dead, and there is not time to adequately train the replacements. Or shall I say, cannon fodder.
So, in an environment like this, there is no expectation that the newly arrived cannon fodder are going to be able to hit anything, at any distance, so issuing rifles with counter bored barrels was fine, as long as it went bang.
Now for you, you have a historical piece, it should go bang, even when new it was maybe a three to four MOA thing, and that was good enough for an issue rifle. If you want a target barrel, you can pay hundreds to have a gunsmith contour a barrel blank and fit the sights, and the rifle will shoot better. It won't be competitive against real target rifles, but it will produce round groups and be more accurate than the typical issue rifle. I would not spend the money trying to find a used Mosin Nagant barrel and have that installed. Military rifle barrels vary so much in quality, you could spend $500 total, and find the new barrel is a stinker.
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