Description

Hornady Superformance 300 Win Mag 165gr GMX — 300 Rounds

The Hornady Superformance 300 Win Mag is the highest-velocity lead-free hunting load in this .300 Win Mag range.

A 165-grain GMX solid copper bullet at 3,260 fps, producing 3,893 ft-lbs at the muzzle.

At $2.00 per round for 300 rounds, the Hornady Superformance 300 Win Mag is the most affordable lead-free option in the category.

Two Arguments for This Load

The GMX is lead-free. For hunters in California and other states with lead restrictions, the choice in .300 Win Mag is between this and the Barnes VOR-TX 180gr TTSX. The GMX is 15 grains lighter, 300 fps faster, and $0.86/round cheaper. Both qualify under California’s Condor Zone regulations.

Superformance propellants add velocity. Hornady developed the Hornady Superformance 300 Win Mag line around progressive propellants that increase velocity 100–200 fps over conventional loads without increasing chamber pressure, recoil, or muzzle blast. The 3,260 fps figure from this load reflects that — the fastest hunting load in the .300 Win Mag category on this site.

The GMX Bullet

GMX stands for Gilding Metal eXpanding. Gilding metal is a copper-zinc alloy used for bullet jackets — here it constitutes the entire bullet, with no lead core.

Unlike Barnes’s X-Bullet design (multiple relief grooves), the GMX in the Hornady Superformance 300 Win Mag uses a single cavity at the tip with a cannelure on the shank.

Polymer tip. Initiates expansion on impact. The tip also improves BC over a flat-meplat or open-tip hollow point design.

Monolithic copper-alloy construction. No lead core to separate. Near-100% weight retention through penetration — the same structural advantage as all solid copper bullets.

Cannelure groove. Controls the amount of petal expansion and maintains structural integrity at Superformance velocities, which are higher than conventional loads and exert more stress on the bullet on impact.

Full Ballistic Data

• Muzzle velocity: 3,260 fps
• Muzzle energy: 3,893 ft-lbs
• G1 BC: 0.447
• Sectional density: 0.248
• Application: Large game, medium game
• Lead free: Yes — California Condor Zone compliant

Where It Fits in the .300 Win Mag Range

Four .300 Win Mag loads now in this category:

• Barnes VOR-TX 180gr TTSX — lead-free, $2.86/round, 140rnd
• Hornady Superformance GMX 165gr — lead-free, $2.00/round, 300rnd
• Hornady American Whitetail 150gr InterLock — conventional, $1.39/round, 360rnd
• Remington Core-Lokt 180gr PSP — conventional, $1.47/round, 340rnd

For California and lead-restriction states: Barnes VOR-TX or the Hornady Superformance 300 Win Mag.

The GMX at $2.00/round for 300 rounds is the better value of the two for a hunter who needs volume for pre-season load development.

Browse the .300 Win Mag ammunition category. Technical specifications are published by SAAMI and by Hornady directly. Safe storage guidance is available from the NSSF.

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SHORT DESCRIPTION (above Add to Cart)

Hornady Superformance .300 Win Mag. 165-grain GMX solid copper bullet — lead-free, California Condor Zone compliant. 3,260 fps, 3,893 ft-lbs, G1 BC 0.447, SD 0.248. Superformance propellant for 100–200 fps velocity gain without added pressure. Brass case, reloadable. 300 rounds (15 × 20-round boxes). Lead-free. Large game hunting load.

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💬 Before You Go — Running GMX in .300 Win Mag?

Hunting with Superformance GMX? Leave a review — especially if you’ve compared it to the Barnes VOR-TX in the same caliber. Both are lead-free .300 Win Mag loads and the terminal performance comparison at typical hunting distances is what California hunters need to read before choosing. And if you came looking for a load we don’t carry, tell us. 🎯

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Please purchase and use ammunition responsibly and in accordance with all federal, state and local laws. Ammunition cannot be shipped to all jurisdictions — verify legal shipment to your address before ordering. Buyers must be of legal age in their jurisdiction. Not for sale to prohibited persons.

Frequently Asked Questions

Is this lead-free? Yes — GMX (Gilding Metal eXpanding) is a solid copper-zinc alloy bullet with no lead core. Qualifies under California’s Condor Zone lead-free hunting regulations.

What does “Superformance” mean? Hornady uses progressive propellants in the Superformance line that increase muzzle velocity 100–200 fps over conventional loads without increasing chamber pressure, felt recoil, or muzzle blast. The 3,260 fps figure reflects this.

How does it compare to the Barnes VOR-TX 180gr TTSX in this range? Both are lead-free .300 Win Mag. The GMX is 15 grains lighter and 300+ fps faster; the Barnes VOR-TX is heavier with more sectional density. The GMX is $0.86/round cheaper and has a larger case count (300 vs 140). For California hunters, both qualify; for large-bodied elk, the heavier 180-grain Barnes may be preferred.

Is the spec table correct — 20 rounds? No. The spec table says 20; the title and slug say 300. The correct quantity is 300 rounds (15 × 20-round boxes).

What is a cannelure groove on a bullet? A machined ring on the bullet shank that limits petal expansion depth on impact, maintains structural integrity at high velocity, and can provide a reference point for crimping.

Can I reload the brass? Yes — standard Hornady brass, Boxer-primed.

What’s the per-round cost? $600 / 300 = $2.00 per round.

Is it semi-auto compatible? Hornady’s Superformance line is listed as compatible with semi-autos, lever guns, and pump actions.