That is the challenge of my question...most, if not all the old military rifles were good guns. They had to be to issue to large armies and have them support the will of the state under bad conditions.
Some rifles that were marginal for me was a 1941 vintage Carcano, it was very particular on ammo, yet it could be very accurate. The action was stiff, this could reduce my rate of fire in battle. Not a bad gun though. I had 2 SKS's rifles, too many moving parts to maintain. And even with a recoil buffer, the bolt body still struck the receiver rear area to some extent. The gas piston assembly housing would become loose after taking it off and on a few times. More accurate than my AK's and the brass spits up, instead of to the side, nice feature at the gun range as I don't hit people to my side with spent cases like my AK likes to do on occasion.
Sure, Swedish Mausers are accurate and well made, had one. Problem with that rifle is it heats up real bad quickly after firing as little as 10 rounds, then stays hot, I once had it so hot after 30 rounds that the top handguard stock was hot to the touch, then it took 20 minutes to cool down! None of my other rifles are that bad.
I have enjoyed shooting other gun club member's AR-15s. Accurate rifle, but I keep thinking of how they kept jamming in Iraq, and lack hitting power. I like the M-14 (M-1, A1) but way too over priced, $1,100 to $1,600 for a plain military rifle with a heavy trigger, give me a break! :x
Had a British No. 4 made in 1948. Fun shooter, and very accurate. Still, the rifle would fail to feed the cartridge just before the last round, heard that this is not unusual. How would you like to go into battle and have the thing fail to feed on a regular basis?! The handguard would slide forward to eventually touch and fowl the front site, despite tightening of the screws on the front barrel band. Heard that this is normal for the design. Noticed craze cracking in the rifling forward of the chamber, got rid of the gun for parts, heard that some of them had blown up from cracking in this area. Pretty bad for a 1948 vintage gun, poor metallurgy?
Had 4 Mosin Nagants, they seem like decent battle rifles. The stripper clips I have tried are garbage, they do not work. Why is it that we don't have proper stripper clips for all these Mosins?
Toyed with getting a MAS 36, nice sites, but the stock is for a midget. Frenchmen are apparently not 6 feet tall on average. Shot a Springfield 1903, seemed nice, but the recoil from that 30-06 with the steel butt plate was too much, handed the gun back to the owner after 5 rounds.
I would not say the above complaints make them bad, but each one had an aspect that was poor.