OK I can't quite make out scuffs on case body in your photo but do see the scuffs on the bullet's nose. That looks like typical ramp contact scuff mark as the nose hits the ramp to begin the process of angling up and out of the magazine.
I did some testing using my BRNO 375 to see, in detail, the mechanics of the feeding/chambering process. As I posted earlier the only thing I notice different with the rifle is the angle of transition between magazine and chamber is greater in the BRNO than in the Win M70.
I experimented with 300 gr WW FMJ round nose bullets seated to different depths to see if I could cause a jam or unusual chambering resistance.
I could not. I tried the bullet seated out to a cartridge OAL of maximum magazine capacity length of approximately 3.800" and it fed out of the magazine fine and entered the chamber fine. That shallow bullet seating depth for the 3.8" OAL exceeded the throat/leade length of the chamber and the bullet contacted the lands before the cartridge fully chambered. I seated that bullet deeper for an OAL of 3.750". That is the "jam" length for a cartridge with that bullet in my chamber. Any longer and and there is definite, hard resistance caused by land contact. I cycled/chambered/extracted the 3.750" length cartridge without issue. I seated a bullet very deep for an OAL of 3.375". It cycled/chambered/exracted without issue.
To reload /resize these test cartridges I used a standard RCBS FL 375 HH die. The loaded cartridge measurements are: case trim length- 2.845". Neck diameter- .398". Upper body diameter- .450". Lower body at web diameter- .510".
The land contact area for this WW FMJ bullet in my chamber is just forward of the cannelure. When checking for OAL jam length, you should see land marks around the circumference of the bullet at the area of contact- one mark for each land. The location of these marks on the bullet will vary depending upon dimensions and shape of chamber's leade and profile of bullet.
I examined the bolt head and tested in hand, by feel, to judge how smooth the entry of the rimmed case head was into the CRF position on the bolt face as it is captured by the extractor. You may check this to see if there is any bur or obstruction to full engagement as the bolt picks up and pushes the case forward while encountering that transition angle when the bullet nose slides up the feed ramp. There has to be some clearance, sloppiness of fit or flex of the extractor for the case head to slightly pivot during that angled transition while being held by the extractor. The cartridge starts parallel to the chamber as it sits in the magazine, the bolt head contacts the case base and starts pushing forward, the cartridge angles up as the bullet's nose slides up the feed ramp toward the chamber, then as the body clears the magazine and slides over the ramp it again returns to parallel with the chamber as it enters for full chambering. That's two angled "turns" for a rigid cartridge while the extractor maintains control of the cartridge during the feed cycle.
I've attached photos showing most of this. It may very well be an oversized ammo issue with either wrong bullet profile, too great a diameter of the bullet's nose section, too great a diameter at one of the key points of the case itself, too long a case or neck where the cartridge case is too long for the chamber (BTW, that is an especially dangerous condition because if forced into the chamber in effect locking the bullet in place at the end of the chamber neck. This can and usually does casue pressure to sky rocket pressure). Be sure to check case trim length- should be between 2.840" and 2.845".
Hope you can find the problem and solve it or avoid it.