OK, I'll go out on a limb with just my best guess, I'll say Remington. I'll list my reasoning.
1. Winchester's had more exposed lead on the nose. I base this on loaded Winchester 7x57 ammo I have on hand.
2. Federal has slightly less exposed lead based on the nose on the 7x57 ammo I have on hand.
Double cannelure tells me this was a bullet made by one of the ammo companies for their ammo.
Frankly, I hesitate to break down the Winchester ammo to check if it has a double cannelure and that weight bullet hasn't been loaded in years. DAMMIT! It has some small collector's status these days.
Anyway, I'll go with it being a Remington factory bullet. Be interesting to find out for sure.
Paul B.
Don't know who made this bullet but if you come up with a Spanish Mauser in 7x57 they will shoot lights out most likely. Those rifles have a throat a mile long because they were designed to shoot 175 gr bullets. Mine shoot really well with the Hornady 175.
Looks a lot like some unmarked 7Mag Dad had that I assumed was Speer because that's all he shot. don't know about the double cannulere though. If I get a chance I'll check. Not really up on this kind of thing. I'd go with the Remington consensus. CL