308 Winchester Barrel Length and Velocity: Winchester 147 grain FMJ

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 receiverShilen .308 1:10 match grade stainless steel unturned barrel blankTACMOD chassis systemBadger Maximized scope railSpuhr ISMS scope mount, and a Nightforce NXS 5.5-22X56mm Mil/Mil Scope.

308 barrel length file photo

Brownells also provided the Winchester 147 grain FMJ ammunition.

Winchester 147 FMJ

 

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

147 FMJ barrel length chart


308 147 fmj values in reverse

 

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″).

Like this? Subscribe to Rifleshooter.com and never miss a post!