7.62x51mm NATO (308 Win) Barrel Length and Velocity: IMI Samson 150 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 IMI Samso 7.62x51mm NATO 150 grain 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 IMI Samso 7.62x51mm NATO 150 grain ammunition.

Samson 150 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

150 IMI barrel length table

final IMI 150 fmj scatterplot

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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