Published: 2024 | Last updated: June 2026
Introduction
Hornady introduced the GMX (Gilding Metal eXpanding) in 2009 from its Grand Island, Nebraska facility, positioning it as a lead-free hunting bullet built around a key technical distinction from competitors like the Barnes TTSX: rather than pure solid copper, the GMX uses a gilding metal alloy of 95% copper and 5% zinc. This is the same alloy composition commonly used for conventional bullet jackets, applied here as the entire bullet body rather than a thin shell around a lead core. The result is a monolithic, lead-free hunting bullet with slightly different material properties than pure-copper monolithics, while still eliminating the core-jacket separation that limits weight retention in conventional cup-and-core designs.
As with the Barnes TTSX, the original article’s claim of “near-100% weight retention” deserves the same calibration applied elsewhere in this series. Independent recoveries and Hornady’s own data more typically show 95-99% retention under hunting conditions – exceptional, but not literally complete. A small amount of material is commonly lost from the expanding petals during deformation even in well-functioning monolithic designs.
The lineup covers .224-inch through .338-inch, 70 to 200 grains, spanning varmint weights through large-game applications in 223 Remington, 270 Winchester, 308 Winchester, 30-06 Springfield, 300 Winchester Magnum, and 7mm-08 Remington. For context on how the GMX’s BCs translate to real trajectories, see the 308 Winchester ballistics guide and 30-06 Springfield ballistics guide. The original article’s own comparison section correctly identifies the GMX’s primary competitors as the TTSX and Nosler E-Tip – this framing is accurate and matches how this series treats the comparison.
Disclaimer: Reloading is an inherently dangerous activity. Always consult current published load data from reputable sources (Hornady, Hodgdon, Sierra) before loading any cartridge. Monolithic copper-alloy bullets generate higher chamber pressures than lead-core bullets of the same weight. Never use lead-core load data for the GMX. Start at the published minimum charge and work up carefully while watching for pressure signs. Never exceed maximum published loads. The information on this page is for educational reference only and does not replace a current reloading manual.
Technical Characteristics
Gilding metal alloy construction (95% copper, 5% zinc): This is the GMX’s defining material distinction from pure-copper monolithics like the TTSX or Barnes TSX. Gilding metal is slightly harder and has different friction characteristics in the bore than pure copper. Hornady’s choice of this alloy for a full monolithic bullet (rather than just a thin jacket, its more common application) reflects a different engineering tradeoff than Barnes made with pure copper – the harder alloy may behave somewhat differently in terms of expansion petal formation and bore wear, though both approaches are well-established and field-proven at this point.
Polymer-tipped boat-tail: The red polymer tip fills and shapes the meplat for BC consistency and drives into the hollow-point cavity on impact to initiate expansion. The boat-tail base reduces drag, contributing to the GMX’s BC figures. Expansion threshold is the standard 1,800 fps, with the bullet doubling in diameter (up to 2x) while maintaining structural integrity as a single retained mass.
Cannelure for reliable feeding: Present across the lineup, supporting crimping for semi-automatic and lever-action platforms and providing a consistent seating reference.
Reduced fouling claim: The original article states 15-20% fouling reduction versus lead-core bullets. As with similar claims for other monolithic designs in this series, this is a directionally reasonable claim (no lead deposit, since there is none) but should be read as an approximate manufacturer comparison rather than an independently verified universal figure – actual results vary by barrel, velocity, and cleaning regimen.
Long bearing surface, seating sensitivity: Like other monolithic designs, the GMX is longer than a lead-core bullet of the same weight because copper alloys are less dense than lead. This produces a longer bearing surface that is more sensitive to seating depth inconsistency than a typical cup-and-core bullet – the original article’s emphasis on precise seating depth (0.010-0.050 inches off lands) is well-founded and consistent with what is generally true of monolithic bullet construction.
Ballistics and Performance
G1 BCs from 0.245 to 0.540 are solid figures that trail the Barnes TTSX (0.295-0.586) at most comparable weights but are broadly competitive with the Nosler E-Tip (0.300-0.523).
The 200-grain .338-inch at BC 0.540 and SD 0.250 is the lineup’s aerodynamic peak, suited to 338 Winchester Magnum and similar cartridges for moose and large bear. This actually exceeds the TTSX 225-grain at BC 0.586 only at the absolute top end of the TTSX range – at the more common 185-grain .338-inch weight, the TTSX’s BC 0.482 trails the GMX 200-grain, though the weight difference complicates a direct comparison.
The 180-grain .308-inch at BC 0.480 and SD 0.271 covers 308 Winchester, 30-06 Springfield, and 300 Winchester Magnum for elk and moose. This trails the TTSX 180-grain at BC 0.484 only marginally, making the two functionally similar at this weight.
The 139-grain 6.5mm at BC 0.450 and SD 0.285 is the flagship 6.5 Creedmoor and 6.5 PRC variant. SD 0.285 is strong for 6.5mm, providing solid elk-level penetration. This trails the TTSX 130-grain at BC 0.454 by a negligible margin despite being a heavier bullet, reflecting the gilding-metal alloy’s slightly different aerodynamic profile at this weight.
The 110-grain .243-inch at BC 0.370 and SD 0.266 covers 243 Winchester and 6mm Creedmoor for deer and antelope, with the same high SD advantage monolithic construction provides at this caliber – comparable to the TTSX 110-grain at BC 0.412 and SD 0.266, though the TTSX holds a clearer BC edge here.
The 70-grain and 80-grain .224-inch variants extend into varmint and predator territory in 223 Remington, providing retained-weight lead-free performance as an alternative to fragmenting designs like the Hornady V-MAX.
Accuracy of 0.5-1.0 MOA is solid for a monolithic hunting bullet, trailing the TTSX’s typical 0.4-0.8 MOA slightly but well within the range needed for ethical hunting shots.
Expert Ballistics Table – Hornady GMX Variants
Data from Hornady specifications. BCs are G1. Verify current figures at hornady.com before load development.
| Diameter (inches) | Weight (grains) | BC (G1) | Sectional Density | Application |
|---|---|---|---|---|
| .224 | 70 | 0.245 | 0.199 | Varmints, predators in 223 Remington |
| .243 | 80 | 0.315 | 0.194 | Deer, antelope in 243 Winchester |
| .243 | 110 | 0.370 | 0.266 | Deer, elk in 243 Winchester and 6mm Creedmoor |
| .264 | 120 | 0.385 | 0.246 | Deer in 6.5 Creedmoor |
| .264 | 139 | 0.450 | 0.285 | Deer, elk in 6.5 Creedmoor and 6.5 PRC |
| .277 | 130 | 0.410 | 0.242 | Deer, elk in 270 Winchester |
| .284 | 130 | 0.395 | 0.230 | Deer in 7mm-08 Remington |
| .284 | 150 | 0.415 | 0.266 | Elk in 7mm Remington Magnum |
| .308 | 150 | 0.415 | 0.226 | Deer in 308 Winchester |
| .308 | 165 | 0.447 | 0.248 | Deer, elk in 308 Winchester and 30-06 Springfield |
| .308 | 180 | 0.480 | 0.271 | Elk, moose in 30-06 Springfield and 300 Winchester Magnum |
| .338 | 185 | 0.450 | 0.231 | Elk, moose in 338 Winchester Magnum |
| .338 | 200 | 0.540 | 0.250 | Moose, large bear in 338 Winchester Magnum |
Comparison Bullets
The original article’s chosen comparison set – Barnes TTSX and Nosler E-Tip – is correct and matches the framing used elsewhere on this site.
The Barnes TTSX is the category benchmark with the longest field record and generally higher BCs at comparable weights, alongside the Triple-Shock grooved shank that reduces bearing surface friction. The GMX is typically somewhat less expensive per bullet, and the two are close enough in terminal performance (weight retention, expansion diameter) that the choice for many hunters comes down to price and specific cartridge load data availability rather than a clear performance gap.
The Nosler E-Tip uses a lead-free alloy with a distinctive cavity-forward design and BCs of 0.300-0.523 – close to the GMX across most of the overlapping weight range, with neither bullet holding a decisive aerodynamic advantage. The E-Tip’s caliber range (.243-.338-inch only) is narrower than the GMX, which extends down to .224-inch for varmint applications.
The Barnes TSX (the non-tipped TTSX predecessor) is a useful reference for hunters comparing pure-copper versus gilding-metal-alloy monolithic construction directly, since the TSX’s hollow-point-only design isolates the material question from the polymer-tip BC contribution.
The Federal Trophy Copper is another lead-free polymer-tipped monolithic competing in the same general category, rounding out the four major lead-free monolithic options available to handloaders.
For hunters who don’t require lead-free compliance, premium bonded options like the Nosler AccuBond and Federal Trophy Bonded achieve comparable or higher BCs with 90-95% retention rather than the GMX’s 95-99%. The Sierra GameKing and Hornady InterLock represent the conventional lead-core alternative at a lower price for hunters not bound by lead-free regulations.
Comparison Table – Premium Lead-Free Monolithic Hunting Bullets
| Bullet | Diameter Range | Weight Range | BC Range | Construction | Weight Retention | Relative Cost |
|---|---|---|---|---|---|---|
| Hornady GMX | .224-.338 | 70-200 gr | 0.245-0.540 | Gilding metal alloy (95/5) | 95-99% | Mid-Premium |
| Barnes TTSX | .224-.338 | 50-225 gr | 0.295-0.586 | Pure copper | 95-99% | Premium |
| Barnes TSX | .224-.375 | 50-300 gr | 0.265-0.550 | Pure copper | 95-99% | Mid-Premium |
| Nosler E-Tip | .243-.338 | 90-200 gr | 0.300-0.523 | Lead-free alloy | 95%+ | Premium |
| Federal Trophy Copper | .224-.338 | 70-180 gr | 0.290-0.480 | Pure copper | 95%+ | Premium |
Applications and Practical Aspects
Varmints and predators (.224-inch, 70-80 grains): Lead-free retained-weight performance for predator hunters who want consistent penetration without the pelt damage of a fragmenting design. Hodgdon Varget and Hodgdon H4895 are appropriate for 223 Remington.
Deer and antelope (.243-inch, 80-110 grains): Hodgdon Varget and IMR 4064 are standard for 243 Winchester.
Deer and elk (6.5mm and .277-inch, 120-150 grains): The 139-grain in 6.5 Creedmoor or 6.5 PRC, and the 130-grain .277-inch in 270 Winchester, are mainstream deer and elk loads. Hodgdon H4350 and Alliant Reloder 16 cover 6.5 Creedmoor; Hodgdon H4350 and IMR 4350 cover 270 Winchester.
Elk, moose, and large game (.284-.338-inch, 150-200 grains): The 150-grain .284-inch in 7mm Remington Magnum, the 165-180-grain .308-inch in 30-06 Springfield or 300 Winchester Magnum, and the 185-200-grain .338-inch in 338 Winchester Magnum are the GMX’s strongest large-game applications. Hodgdon H4831SC and Alliant Reloder 22 cover 300 Winchester Magnum and 300 WSM.
Reloading
Hornady publishes GMX-specific load data in its reloading handbook and app, covering most major hunting cartridges.
Primers: Standard large rifle primers for most applications. CCI 200, Federal 210, Winchester WLR, and Remington 9-1/2 are reliable. For magnum cartridges, CCI 250 or Federal 215 magnum primers are appropriate.
Cases: Standard brass from Winchester, Federal, Hornady, and Lapua are all appropriate. For magnum precision loads, Lapua brass provides the best case consistency.
Seating depth: Start 0.020 to 0.050 inches off the lands. As with other monolithic designs, the GMX’s longer bearing surface benefits from systematic testing in 0.005-0.010 inch increments rather than a single starting point.
Crimp: Light to medium roll crimp at the cannelure for semi-automatic and lever-action platforms. Bolt-action hunting rifles do not require crimping.
Powder Selection by Application:
| Application | Caliber | Bullet Weight | Recommended Powders |
|---|---|---|---|
| Deer | 243 Win | 80-110 gr | Hodgdon Varget, IMR 4064, Hodgdon H4350 |
| Deer/elk | 6.5 Creedmoor | 120-139 gr | Hodgdon H4350, Alliant Reloder 16, Alliant Reloder 23 |
| Deer/elk | 270 Win | 130 gr | Hodgdon H4350, IMR 4350, Alliant Reloder 19 |
| Elk | 7mm Rem Mag | 150 gr | Alliant Reloder 22, Hodgdon H4831SC, IMR 7828 SSC |
| Deer/elk | 308 Win | 165-180 gr | Hodgdon Varget, IMR 4895, Alliant Reloder 15 |
| Elk/moose | 300 Win Mag | 180 gr | Hodgdon H4831SC, Alliant Reloder 22, Alliant Reloder 26 |
| Moose/large bear | 338 Win Mag | 200 gr | Hodgdon H4831, IMR 7828, Alliant Reloder 22 |
Reloading Parameters Summary:
| Parameter | Guideline |
|---|---|
| Neck tension | 0.002-0.004 inch interference |
| Seating depth | 0.020-0.050 inch off lands; test in 0.005-0.010 inch increments |
| Crimp | Light to medium roll crimp for semi-auto/lever-action; optional for bolt-action |
| Minimum expansion velocity | 1,800 fps at target distance |
| Weight retention | 95-99% typical (not literally 100%) |
| Extreme spread target | Under 15 fps for hunting accuracy |
Frequently Asked Questions
Q: Is the GMX’s “near-100% weight retention” claim accurate?
A: Similar to the Barnes TTSX, this should be read as 95-99% rather than literally complete retention. Independent recoveries typically show a small amount of material loss from the expanding petals during deformation. This remains exceptional performance compared to conventional cup-and-core bullets at 65-85% retention, but “near-100%” in marketing language is rounding rather than a literal physical description.
Q: What is gilding metal, and why does Hornady use it instead of pure copper like Barnes?
A: Gilding metal is a copper-zinc alloy (typically 95% copper, 5% zinc) traditionally used for conventional bullet jackets because of its favorable bore-friction and expansion characteristics. Hornady’s choice to use this alloy for the entire GMX bullet body, rather than just a thin jacket, is a different engineering approach than Barnes’s pure-copper TTSX. Both materials are well-proven for monolithic bullet construction. The practical difference for handloaders is modest – load data, pressure characteristics, and expansion behavior are broadly similar between the two approaches, though Hornady’s specific GMX load data should be used rather than substituting TTSX data, since the alloys are not identical.
Q: How does the GMX compare to the TTSX in actual field performance, not just published specifications?
A: The published BC figures show the TTSX with a modest edge at most comparable weights (roughly 0.02-0.05 BC points), and the TTSX’s accuracy specification (0.4-0.8 MOA) is slightly tighter than the GMX’s (0.5-1.0 MOA). In practical hunting terms – terminal performance, weight retention, penetration depth – the two bullets are very close, and many hunters report comparable field results between them. The TTSX has a longer accumulated field record given its earlier introduction and broader market adoption. For hunters deciding between the two, price and the availability of load data for a specific cartridge are often the more practical deciding factors than the modest performance gap.
Q: Why does the original article mention “higher recoil in lighter calibers” as a drawback?
A: This claim deserves scrutiny. Recoil is a function of bullet weight, powder charge, and cartridge – it is not a property of the bullet’s jacket material or construction type. A GMX bullet does not inherently generate more recoil than a lead-core bullet of the identical weight fired with the identical powder charge from the identical cartridge. If GMX loads in some cartridges produce more felt recoil, it would be because monolithic bullets at a given caliber are sometimes loaded lighter than lead-core options of the same nominal cartridge to achieve adequate sectional density, requiring a different powder charge – not because the bullet material itself produces more recoil. This is not a meaningful inherent drawback of the GMX design.
Q: Can I use the GMX for elk and moose at standard, non-magnum velocities?
A: Yes – similar to the TTSX, the GMX’s 1,800 fps expansion threshold is reached well past typical hunting ranges from standard cartridges. From a 308 Winchester 180-grain GMX at approximately 2,600 fps muzzle velocity, the bullet remains above the threshold to roughly 350 yards. For most North American elk and moose hunting at typical ranges inside 300 yards, standard cartridges with the GMX provide reliable expansion without requiring a magnum.
Q: Should I choose the GMX or the Nosler E-Tip for a 7mm Remington Magnum elk load?
A: Both are viable lead-free options at comparable price points. The GMX 150-grain .284-inch at BC 0.415 and the E-Tip at similar weights in the same caliber have broadly comparable BCs – neither holds a decisive advantage. The practical difference comes down to which manufacturer’s load data is available and validated for your specific powder choice, and whether you have a preference based on prior experience with either brand’s monolithic construction. Both are well-established, field-proven designs at this point.
Conclusion
The Hornady GMX is a well-established lead-free hunting bullet using gilding metal alloy construction, occupying a competitive middle position between the category-leading Barnes TTSX and the Nosler E-Tip. Its BCs trail the TTSX modestly at most weights while remaining close to or competitive with the E-Tip, and its weight retention (95-99%, not literally 100% despite marketing language) is in line with other premium monolithic designs.
Choose the GMX if: you hunt in lead-restricted areas including California; you want a well-documented monolithic bullet with comprehensive Hornady-published load data; or you want performance close to the TTSX at a somewhat lower price point.
Choose something else if: you want the highest available BC in a lead-free monolithic – the Barnes TTSX generally holds a modest edge at comparable weights. If you want a fragmentation-based terminal mechanism rather than a single mushrooming projectile, the Lehigh Defense Controlled Chaos or Lehigh Defense Maximum Expansion offer alternative lead-free approaches. If lead-free compliance is not required, premium bonded bullets like the Nosler AccuBond, Federal Trophy Bonded, or Winchester Expedition Big Game are worth comparing.
Disclaimer: Reloading involves inherent risks. The GMX is a monolithic gilding-metal alloy bullet that generates higher chamber pressures than lead-core bullets – never use lead-core load data as a starting point. Always use current load data from Hornady or other published manuals. Start below maximum charges and increase gradually. Wear eye protection at all times. The author and myreloading.com are not responsible for injuries or property damage from reloading or shooting handloaded ammunition.
Have you loaded and hunted with the Hornady GMX? Leave a comment with the details: weight, cartridge, game, range, shot angle, and what you observed. How did it compare to a Barnes TTSX or Nosler E-Tip you may have used in the same cartridge? Recovered bullet weights and photos are always valuable to other hunters evaluating their lead-free options.
Editorial note: Originally published 2025, revised June 2026. The update corrected the original article’s claim of “near-100% weight retention” to the more accurate 95-99% supported by independent recoveries, consistent with the same correction applied to the Barnes TTSX elsewhere on this site. Added detailed explanation of the gilding metal alloy (95% copper, 5% zinc) construction and how it differs from pure-copper monolithic designs like the TTSX. Applied scrutiny to the original article’s “higher recoil in lighter calibers” claim, clarifying that recoil is a function of charge weight and bullet mass rather than jacket material. Added direct comparison guidance for hunters choosing between the GMX, TTSX, and E-Tip. Added FAQ covering six common questions. Applied full internal linking throughout.
