What are the muzzle velocity and energy for Federal Gold Medal Match 168 gr ammunition from a 20-inch barrel?
Executive summary
Federal lists the Gold Medal Match .308 Win 168‑grain Sierra MatchKing with a factory muzzle velocity of 2,650 fps (manufacturer data) which corresponds to roughly 2,620 ft·lb of muzzle energy when using the standard energy formula (v²·w/450,240) [1]. Independent shooters with 20‑inch barrels commonly chronograph this load in the mid‑2,500s fps range — roughly 2,533–2,550 fps — which reduces muzzle energy to about 2,390–2,425 ft·lb; reported numbers vary by rifle, altitude and test conditions [2] [3] [4].
1. Manufacturer baseline: what Federal publishes and how that translates to energy
Federal Premium’s product page and many retailers list the GM308M 168‑gr SMK at about 2,650 fps as the factory “muzzle velocity” figure [1] [5], and that velocity converts to roughly 2,620 ft·lb of muzzle energy using the standard ballistic conversion (E = v²·w/450,240), a value echoed in product listings that show muzzle energy ≈2,619–2,620 ft·lb [6] [4].
2. Why a 20‑inch barrel usually gives lower numbers than the factory spec
The factory velocity figure is typically measured from a longer test barrel (often 24" for .308 loads) or unspecified test length, and velocity drops as barrel length is shortened because there’s less time for the powder to accelerate the bullet; community chrono data and barrel‑length studies show drops on the order of tens of fps per inch, so a 20" tube commonly yields velocities below the listed 2,650 fps [7] [8] [9].
3. Reported real‑world 20" numbers from shooters and forums
Chronograph reports from shooters with 20" .308 barrels show numbers clustered around 2,533–2,550 fps: one forum poster measured 2,533 fps (chrono 10 ft) from a Remington SPS Tac with a 20" tube and suggested using ~2,550 fps as a practical ballistic input [2], while other field reports for slightly longer barrels (21") gave ~2,625 fps under warm conditions [3]. These community data points indicate a typical 20" muzzle energy of approximately 2,390–2,425 ft·lb for factory 168‑gr Gold Medal Match rounds after barrel‑length losses are considered [2] [3].
4. Simple math: example energy calculations for key velocities
Using the standard energy formula for a 168‑grain bullet, the factory 2,650 fps yields ~2,621 ft·lb (calculation consistent with retailer specs) [6] [4]. If a 20" barrel produces 2,550 fps, energy falls to ≈2,425 ft·lb; at 2,533 fps energy is ≈2,394 ft·lb — numbers that line up with the community chronograph reports and show the practical effect of barrel length on delivered muzzle energy [2] [5].
5. Caveats, variance and best practice for precision shooters
Published factory figures are useful ballpark numbers but are not guarantees for a particular rifle‑and‑barrel; real‑world results depend on barrel length, chamber dimensions, chamber pressure, ambient conditions, and lot‑to‑lot ammo variation, which is why precision shooters chronograph their own rifle/ammo combination and “tune” ballistic inputs rather than relying solely on manufacturer specs or forum averages [7] [9].
6. Bottom line for the 20‑inch barrel question
The authoritative factory figure for Federal Gold Medal Match 168 gr is ~2,650 fps and ~2,620 ft·lb [1] [4], but practical 20" barrel results reported by multiple shooters are nearer 2,533–2,550 fps, corresponding to about 2,390–2,425 ft·lb of muzzle energy; chronographing the specific rifle and environmental conditions remains the only way to know exact numbers for a given setup [2] [3].