Hi, I'm new here so bear with me if I'm doing this wrong.

I have a knife that's been in the family for a really long time. It's a Chinese knife and it's...old. Either Shang Dynasty or Zhou. Unless it's a replica.

Anyway, here are the pictures of the knife.

Inscription
Front
Back

I'm given to understand that subtle differences in the characters make a big difference, things my untrained eye wouldn't be able to detect in that trace I made. If it's not clear enough, I can try to get a better picture of the inscription itself. Someone suggested a charcoal rub or something, but I don't have the tools for that.

If anyone knows what it said, I would be so grateful. Thank you for your time and help!

It looks like a studio name, but it would be easier to read if it weren't upside down.

It's upside down? Well that's embarrassing.

Inscription

I was kind of hoping you'd invert the photograph rather than the handdrawn image. The first two characters on it are too distorted for me to identify but the last two are 友庫 "right [hand] storehouse".

There's no way you could take a rubbing of the handle and post that, is there?

I do think the last two characters are 左庫 "left storehouse" instead, as I have searched for a while and came across this ancient "鏚" which had the identical inscription, and there are actually a couple of weapons with the same inscription (which also suggest that the characters may be 左軍 "left army" instead).
As for the first two characters, I can see a 方-like part at the bottom of the first. (Compare this seal script "方")
And also a 卂-like part at the left of the second character. (Compare right part of 訊 here) but that's about all I can make out from that. Of course a lot of possibilities exist as Chinese characters have lots of variations especially in the earlier forms, and different characters can look very alike.