MagnaCut vs. M390: The Battle of the Super Steels

The Contestants: Old King vs. New Challenger

For over a decade, Böhler M390 (and its American twin, CPM-20CV) has been the gold standard for premium pocket knives. If you bought a high-end knife from Zero Tolerance (ZT) or Microtech in the last ten years, chances are it was M390. It offered incredible edge retention and near-perfect stainless properties.

But in 2021, Dr. Larrin Thomas changed the game with the release of CPM MagnaCut. It promised the impossible: the toughness of a carbon steel with the corrosion resistance of a dive knife, all while holding an edge. Is it all hype, or is M390 officially obsolete?

What is MagnaCut?

CPM MagnaCut is a powder metallurgy steel specifically designed for knives. Unlike other steels adapted from industrial ball bearings or plastic mold injectors, MagnaCut was engineered from the molecular level up to solve the “Stainless Trade-Off.”

Usually, to make steel stainless (add Chromium), you sacrifice toughness (it becomes brittle). MagnaCut eliminates the Chromium Carbides that cause brittleness, resulting in a steel that is incredibly tough yet virtually rust-proof.

Brands like Spyderco and Hinderer have aggressively adopted it for their flagship models.

What is M390?

Böhler M390 is a “Super Steel” from the 3rd generation of powder metallurgy. It is packed with Chromium and Vanadium. This creates a massive amount of hard carbides.

The Result: A knife that stays sharp for an incredibly long time and resists rust very well. However, those same hard carbides make it notoriously difficult to sharpen and prone to micro-chipping if the blade hits a staple or a rock.

Head-to-Head Comparison

Let’s look at the raw data. Understanding these differences starts with knowing the basics of stainless vs. carbon steel characteristics.

Toughness: The Game Changer

This is where MagnaCut destroys M390. “Toughness” measures a steel’s resistance to chipping or breaking under impact.

M390 is brittle. If you pry with it or drop it, the tip might snap. MagnaCut, however, has toughness levels rivaling non-stainless tool steels like CPM-4V. This makes MagnaCut suitable for large camp knives and choppers, whereas M390 should strictly be used for slicers.

Edge Retention: The M390 Stronghold

If your only goal is to cut cardboard boxes all day without stopping, M390 still wins. The high volume of vanadium carbides in M390 makes it extremely abrasion-resistant.

MagnaCut is no slouch—it holds an edge better than S30V or S35VN—but it falls slightly short of the sheer longevity of M390. However, many users argue that MagnaCut’s edge is more “stable,” meaning it doesn’t micro-chip, so it might actually feel sharper for longer in rough use.

Sharpening & Maintenance

Because M390 is so wear-resistant, removing material to sharpen it is a chore. You almost certainly need diamond plates or a high-end guided system. MagnaCut acts much more like a carbon steel on the stones; it takes a fine edge quickly and deburrs easily.

Regardless of which you choose, you need the right tools. Check out our guide on best knife sharpening systems to keep these super steels performing at their peak.

Final Verdict: Which is Best?

Choose MagnaCut If:

• You want a “do-it-all” knife that won’t rust or chip.
• You use your knife for hard tasks (camping, wood carving, construction).
• You live in a humid/coastal environment (saltwater resistance is incredible).
• You sharpen your own knives and value ease of maintenance.

Choose M390 If:

• You prioritize edge retention above all else.
• You use your knife strictly for slicing (opening packages, food prep).
• You don’t mind spending extra time sharpening (or you pay someone to do it).
• You want a mirror-polished finish (M390 polishes beautifully).

Expert FAQs