Introduction
I cut back a 28″ barrel 308 Winchester one inch at a time, to 16.5″, and recorded velocity data for four different cartridges. The data was summarized in 308 Winchester / 7.62x51mm NATO: Barrel Length versus Velocity (28″ to 16.5″). This post provides Rifleshooter.com’s readers the complete data set for Winchester 147 grain FMJ ammunition.
The test rifle was built with the following parts from Brownells; including a Remington 700 short action receiver, Shilen .308 1:10 match grade stainless steel unturned barrel blank, TACMOD chassis system, Badger Maximized scope rail, Spuhr ISMS scope mount, and a Nightforce NXS 5.5-22X56mm Mil/Mil Scope.
Brownells also provided the Winchester 147 grain FMJ ammunition.
Review of test protocol
Ballistic data was gathered using a Magnetospeed barrel mounted ballistic chronograph. At each barrel length, the rifle was fired from a front rest with rear bags, with five rounds of each type of ammunition. Average velocity and standard deviation was logged for each round.
Once data was gathered for each cartridge at a given barrel length, the rifle was cleared and the bolt was removed. The barrel was cut off using a cold saw. The test protocol was repeated for the next length.
Temperature was 47F.
Data
For a complete discussion of the methods used and data collected in this experiment, please see 308 Winchester / 7.62x51mm NATO: Barrel Length versus Velocity (28″ to 16.5″).
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