M4 vs M390

I have a GB2 M4 I've babied whereas I am carefree with the M390s I have. All the talk about corrosion and what not has me hesitant to put the GB2 to use. I don't mind it aging or developing a patina frankly but what is the risk of not treating it with kid gloves? Someone have an example of a M4 horror story to share or is it overblown?

- Right after I posted this, I noticed a recent long thread on the GB2 which covers hard usage. Should have known this was discussed already somewhere.
 
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I edc a GB1 since it was first released but while we'all are on the subject of M4 steel blade knives, has anyone used the kershaw sprint run m4 with the DLC blade coating? I'm thinking it would make the blade more corrosion resistant and I'd like to see Spyderco should adapt a DLC coating on the GB. Thoughts?

Blur M4, Navy Blue - YouTube
 
GatorFlash1 said:
I edc a GB1 since it was first released but while we'all are on the subject of M4 steel blade knives, has anyone used the kershaw sprint run m4 with the DLC blade coating? I'm thinking it would make the blade more corrosion resistant and I'd like to see Spyderco should adapt a DLC coating on the GB. Thoughts?

Blur M4, Navy Blue - YouTube
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Not sure about that but Blade HQ does use M4 for their signature runs and at least half of them were black DLC. You could either try to find one of those or wait for the next exclusive.
 
Thanks for the info, I'll check it out. Do you know if DLC coating makes a steel rust resistant?
 
I'm a Para 3 hoarder. It's a sickness, I know, but one that allows me to speak to the performance of many steels in that format.
  • M4 - This steel will patina and rust. Mine did, and if that bothers you look elsewhere. If you don't care about that, or live in an arid climate, it's a spectacular choice for an EDC. It's tough, easy to sharpen and retains that edge for a respectable length of time.
  • M390 - It's stainless. To get that you have to give up performance in other areas. If you understand this point, then you're ahead of many knife people out there. That said, it's still a very good all-around steel. It is a bit of a chore to sharpen if you don't have diamonds, but then there's no reason to invest in the Super Steels if you don't have diamonds. Unless you just enjoy self punishment. Weirdo.
I advise my friends to follow Dr. Larrin's advice when he said, "Non-stainless vanadium-alloyed powder metallurgy steels tend to have the best balance of toughness and edge retention such as Z-Tuff, CPM-3V, CPM-CruWear, and CPM-10V."

I love CruWear, and since I don't care for rust on my EDC I picked up the DLC coated version that was just recently released. It comes to a sticky-fine edge in no time, and stays that way for a while even with some relatively hard use. I cut down a bucket full of zip-ties from a chain link fence, and wasn't always careful of how the blade popped through the plastic tie and into the chain link on the follow through. Still screamin' sharp after all that.
 
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Aaron Gough did a practical comparison of different blade coatings (He uses A2 steel for his knives which should comparable to M4 when it comes to rust resistance - or a lack thereof) - it is worth a look:

 
GatorFlash1 said:
Thanks, that is good link.
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Coming soon.
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Don M said:
I have found A2 to be noticeably more corrosion resistant than M4.
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And the blade finish might have a lot to do with that. How is the Para2 blade finish? In my experience, the CPM-M4 in my GB1 is about the same as A2 for corrosion resistance.
 
lambertiana said:
And the blade finish might have a lot to do with that. How is the Para2 blade finish? In my experience, the CPM-M4 in my GB1 is about the same as A2 for corrosion resistance.
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True. The A2 I have does have a finer surface finish than the M4 I have.
 
As for the M4 vs M390.. I have a M4 DLC Military and a M390 DLC Manix..

I'm finding both of them very enjoyable. I like the toothy edge M4 will take. Just a little more biteee than the M390 takes.

Both are pretty great, in the knifes they are in.
Different steels for different sized blades, for different cutting tasks..

Spyderco makes it SO easy to make all tasks easy!
 
I live in Mississippi and carry my GB2 a good bit. No corrosion problems so far. Not even much patina yet. Will like to see what happens when it gets warmer out and it gets some sweat on it.

My dlc and cerakoted m4 blades have been great.
 
M4 is a high speed tool steel which is meant to take a high hardness (63 hrc) and hold an edge for a good long time. Due to its strength it can be used to make edges which are super thin behind the apex and cut like a lazer.

M390 is a powdered stainless steel which has a very high chromium content. So high in fact that I think it's just behind rustproof steels like vanax and lc200n in terms of its tendency to rust. I'm pretty sure it's optimal when run at around 62 hrc. Because it's stainless you are giving up on toughness. However, a benefit to this steel is that it is quite easy to sharpen.

I have a benchmade valet in m390 and I like it a lot. Takes a killer edge and sharpens up like a dream on my shapton stones. Unless you need the rust resistance though, I would say M4 has an edge on this steel.
 
A big edge if toughness is an important criteria. I like hollow grinds thinned out behind the edge, so M4 for me is a superior steel. I think a sprint run of GB1's in DLC M4 with micarta scales would be a lightning fast seller.
 
Officer's Match said:
A big edge if toughness is an important criteria. I like hollow grinds thinned out behind the edge, so M4 for me is a superior steel. I think a sprint run of GB1's in DLC M4 with micarta scales would be a lightning fast seller.
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Imo if superior strength, thereby enabling superior geometry is your main criteria it's hard to beat the tool steels. Certainly no stainless steel outside of aeb-l or nitrobe 77 (now discontinued) can hold a geometry like M4 or k390.

If m4 is to your liking you might want to check out s390, k390, rex 45 and vancron superclean. Vancron in particular is absolutely insane: tougher than k390, able to take a higher hardness and very very wear resistant. The downside is that only a few custom knife makers are going to be using this steel because of how rare it is.
 
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