A lot better!
But don't be afraid to increase the contrast even more.
Some more crits though, you have to add in the cracks between the different parts, also adding a pattern to the attachment rails. Because it's still looks a lot like a single shape.

(hm, top railing is the wrong color, looks kinda off)
I was just gonna make a few changes in the edit, but then I started looking at the reference and it went kinda crazy..
I notice the part between the grip and the stock it goes down a bit in yours, but in the reference it's completely straight, did you draw it partly by memory?
I think you have to train yourself to look at references without thinking too much and just seeing what's there, not making any assumptions like "well a barrel is always straight" even if it's true, because otherwise memories will start interfering..
Also it's really useful if you compare the lines and see how parts line up in relation to each other, which I find really interesting and that's why I like doing edits like this when there is a clear reference.
It's really good training to get better perception and really see what's there, because the brain likes to make assumptions and look at the whole thing instead of the individual parts.'
edit: I just noticed something else on the reference and had to fix it..

