Case by Case
For the past month I have experimented with my 91/30 to see the difference w versus w/o the bayonet. So far the results would seem to indicate that the Bayonet on tends to produce a wider pattern than shooting w/o and for mine, the rifle produces a tighter pattern with the barrel firmly encased and shimmed with cork versus floating. And as they say in the Ad's "Your performance may vary."
As to the question you ask about what the Soviets did, I haven't a clue. You will have to do your own tests to come to any conclusion. Start with a 75 yard target, remove the bolt and look down it, check and align the front sight as needed. Or, you could go high tech like I did. I purchased one of those laser bore sighters that slip in the chamber. Unfortunately, I could not find one in 7.62x54r and had to settle for one in .308 costing about 30 bucks. Then I took a spent 7.62 brass case, cut it so that the laser would fit inside. Most importantly, I cut two small tabs up where the case necks in and bent these tabs over. Don't worry, the laser is pencil thin and these tabs don't get in the way. What they do allow is for you to push the assembly out.
To use you turn on the 308 laser stick it in the 7.62 case and manually push into the chamber softly. I had to wiggle the laser til I had a dot coming down the center of the barrel. This is checked by placing cello tape over the muzzle.
One last tip, get some of that reflective tape and stick it to something 100 yards away. I have an old dead tree out back that I use. This still isn't perfect, but it does get you very close. I used the above technique to zero in my scope and was only off by 6 clicks on the verticle plane.
While mine is more accurate w/o the bayonet, I actually prefer to shoot it with.
Let us know what your results are.
KKKKFL
