Wolfdogs question on 8mm ammo brings up a problem I have with one of my rifles.I have 2 8 mms,one is a Czech1924 straight bolt that shoots acceptable groups off the bench for hunting purposes.The other,A 1948 Yugoslavia shoots 6" groups at 75 yards.Had a gunsmith look at the barrel to see if he could see something that I couldn't,he didn't see a problem.The only ammo I have is Reminton 170 grain soft points,bought before the great ammo shortage.Is it possible this old military rifle discriminates on what you feed it?I know this can be a issue with some commercial rifles,I've got a Ruger .257 Roberts that definitely prefers some ammo over others but I've never heard of this in a old military rifle.I'm interested in hunting loads for it,not the surplus ammo that's out there.

Definitely can be picky ! What's the bore measure ? That could be one of the big issues. Alot of the eastern block guns will have different bore diameters and ammo manufacturers will generally go to the smaller diameter so it can safely shoot in whatever . Kind alike how AK,SKS , and mosin barrels can be anywhere from .308-.316 bire diameters but if you check alot of ammo made in the use it's .308 dia bullets and most people have to bump up to like a .311 to get good accuracy. Slugging the bore (If your smith hasn't already) would be a great staring place. Slugged my mosin and found out it's like .314.
Also it could just be that it plain hates those rounds you have.said it's the only stuff you've tried right ? Some of these older pawn shop finds I get won't hit the broad side of a barn with a few different kinds of ammo and then do amazing with another. Last real bad one I had was such a pain . By the time I found a factory round that shot good I added it up and could have bought dies, power and bullets !

Military rifle behave no different as regards to ammo choice. The thing is that military rifles at work don't get much of a choice as to what they get fed. For most of us, " military accuracy " is less that acceptable ... We are not happy with just wounding a deer at a couple of hundred yards. We want to drop it right there waiting for us to pick it up. So yes you can improve accuracy of that old rifle by trying out different loads , bullet weights , powders seating depth etc. As long as the chamber, rifling and crown are ok.

I hear the term "slugging the barrel" used a lot now days.I need this explained to me as I have no idea what it means.

Its one way to measure the diameter of a barrel.

Basically all your doing is taking a larger then bore diameter soft lead projectile ( most people just use a muzzle loader round ball since their cheap)you lube it up then basically just shive it down the barrel one way then put the other. The rifling will engraved marks on the lead ball bullet or whatever and you just measure that to see what your bore is. You can use some stuff called cero safe as well

Using a pure lead ball slightly oversize and driving it the length of the bore with a wood or other non marking softer than steel rod. Then measuring the result. It will be the smallest interior diameter. You can also identify any tight spots as you go. Tight spots can be bad.

a replacement barrel plus gunsmith service aint cheap but a new barrel will cure it. bore size and consistancy will not be problem then

Got the answers that I was looking for,thank you all.