I read about keeping the chamber clean and always kept mine very clean and oiled the other issue was the plastic shroud for the bolt would break off I had that happen and I have been running it without.
I never did much shooting besides sight in and hunt once I realized it had a limited time.
when I started reloading for it I used an M1 Garand load which was intentional so I could have one round for both the M1 and the 742
the 740 was being developed at basically the same time as the M1 then put on hold for WWII
M2 ball was the ammo of the time period and at the time Rem ammo was nearly the same I suspect the development work takin place in the late 30s was mostly using the same velocity 30-06 as was being used for the M1
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went from brass sailing 30 feet to drops them in a nice little pile about 4 feet away , very soft shooting and the buck I shot didn't know the difference
the differences 740 to 742 were ejector , and extractor were beefed up.
the barrel threads became left hand so it wouldn't walk loose
the ejection port cover went from metal to plastic
the sights went to screwed on form dovetails or soldered
all these changes followed to the 760 to keep them the same but no change to the 760 numbers
here is a lot of good info on the 740/742/7400
https://www.leeroysramblings.com/Gun%20Articles/remington_7407427400_semiauto.htmlhere is info on the 760/7600
https://www.leeroysramblings.com/Gun%20Articles/remington_760_7600_pump_rifle.html