What differences in trajectory and long-range drop exist between 7.62x51 NATO and 6.8x51 at 800–1500 meters?
Executive summary
At long range (800–1,500 m) available reporting indicates the new 6.8×51 (.277 Fury) was adopted to extend “overmatch” beyond legacy 7.62×51 performance, with SIG describing a high‑pressure 6.8×51 load at ~80,000 psi that yields flatter trajectory and greater terminal performance; commentators and forums claim effective reach around 1,200 m for 6.8×51 versus roughly 800–1,000 m for 7.62×51 [1] [2] [3]. Precise drop figures depend on bullet weight, muzzle velocity and BC; public ballistics charts and calculators are used frequently because manufacturers and military releases give few directly comparable drop tables in the sources [4] [5].
1. Why the Army changed calibers — range and trajectory as the stated goal
The Army’s selection of the 6.8×51 (SIG .277 Fury) is framed by sources as a search for "overmatch": a cartridge intended to deliver flatter trajectories, more retained energy out past typical 7.62 engagement distances, and thus effective hits at longer ranges — reporting and commentary note claims that the 6.8×51 provides longer effective range (often cited ~1,200 m) compared with roughly 800 m commonly attributed to 7.62×51 doctrine [6] [2] [3].
2. Pressure, velocity and why trajectory differences exist
A core technical difference reported is chamber pressure: SIG and some reporting list the 6.8×51 combat load at about 80,000 psi, significantly higher than conventional 7.62×51 NATO levels (~60.2k NATO-method referenced elsewhere), enabling higher muzzle velocities and therefore reduced drop and flatter flight for the 6.8×51 compared to many 7.62 loads [1]. This is why the new cartridge is advertised as having improved long‑range trajectory and lethality [1] [6].
3. What the public sources actually quantify — scarcity of direct drop tables
Public-facing product pages and enthusiast sites provide ballistics charts and calculators but the sources supplied do not contain a single, authoritative drop table that directly compares 7.62×51 M80/M118 long‑range rounds with the specific 6.8×51 military combat load across 800–1,500 m. Manufacturer/third‑party charts exist (e.g., SIG/MCARBO charts and ShootersCalculator) and are commonly used to produce trajectory graphs, but the reporting here emphasizes using those tools rather than supplying one canonical comparison [4] [5] [7].
**4. Practical ranges quoted by multiple sources — different standards, same story**
Multiple sources converge on the practical rule: 7.62×51 is normally treated as effective to ~800 m by Army doctrine and to ~1,000 m in some USMC or competitive contexts; 6.8×51 is promoted as extending effective, flatter trajectory and energy beyond that envelope — forum commentary and analysis cite roughly 1,200 m potential for the 6.8×51, but these are estimates and depend on barrel length, load, and platform [3] [8] [2] [9].
**5. How much less drop? — answer: it varies; use BC/MV for real numbers**
The exact drop difference at 800–1,500 m depends on bullet ballistic coefficient (BC), projectile mass, and muzzle velocity. Sources repeatedly stress that "trajectory varies load to load" and that calculators or manufacturer charts are required to compute drop for a chosen bullet [10] [5]. The collected reporting therefore supports a qualitative conclusion — 6.8×51 high‑pressure loads will produce measurably less drop and more retained energy at extreme ranges than many standard 7.62×51 loads — but it does not provide a single numeric inches/centimeters drop comparison across 800–1,500 m in the supplied material [1] [4].
**6. Alternate viewpoints and limitations in the reporting**
Enthusiast forums and independent commentators are mixed: some users say trajectories are “similar” inside a few hundred meters but diverge past ~300 yards; others caution the logistical and cost tradeoffs or argue marginal improvements for expense [11] [2]. Forgotten Weapons commentary and skeptical forum posts raise operational and supply concerns and highlight that there are multiple pressure/load types for 6.8×51 (training vs. high‑pressure combat), complicating direct comparisons [12] [2]. The supplied sources do not include formal, peer‑reviewed ballistic test data listing drop at 800–1,500 m for matched test conditions.
**7. Practical recommendation for a shooter or analyst**
To get reliable drop numbers for your use case, pick the specific bullet weight and BC you expect to shoot, choose barrel length and atmosphere, then run those inputs through a ballistics calculator or the manufacturer’s chart (shooters calculators and MCARBO/SIG charts appear in the reporting as common tools) — the sources direct readers to those resources because there is no single default trajectory to cite [4] [5] [7].
Sources used in this piece emphasize the Army’s rationale, SIG’s pressure/ballistics claims, manufacturer charts and community discussions; direct numerical drop tables for a controlled 7.62×51 vs 6.8×51 comparison at 800–1,500 m are not present in the available reporting [1] [4] [5] [6] [3] [2].