FMJ yaw and upset performance

[Tony Williams]

On the subject of barrier penetration, I found this interesting account:

Jason Gillis, a former Army staff sergeant, first witnessed the M855’s shortcomings in 2004 on the streets of Baghdad. He was a squad leader with 2nd Brigade Combat Team, 82nd Airborne Division, on patrol when a vehicle began speeding toward his unit.

After several warnings, “both of our M249s opened up instantly, forming a crisscross pattern of tracer that met at the vehicles engine compartment and windshield. Within seconds, riflemen and grenadiers were executing magazine changes while the vehicle kept rolling and finally stopped 10 meters from my lead troops,” Gillis recalled in an e-mail to Army Times. He is now a freelance writer who often focuses on military small-arms issues.

“Assuming the driver was most likely riddled beyond recognition, we were all astounded to see the driver emerge from the vehicle completely unscathed,” Gillis wrote. “Closer inspection revealed that the M855 ammunition had failed to effectively penetrate the vehicle’s windshield despite the fact over 400 rounds were expended at extremely close range and on target.”

I have read similar complaints about barrier (in general) and windscreen (in particular) penetration from a study of combat experience carried out by the Royal Marines last year (which included the SBS - their SEALS). This study showed that only about half of the Marines consulted felt that the 5.56mm ammo was "fit for purpose"; there was a majority view that an intermediate round could solve these problems; and that if that wasn't possible, they tended towards entirely replacing 5.56mm with 7.62mm. This wasn't just due to the longer range, but to greater effectiveness even at short ranges (they have a new 7.62mm rifle, the L129A1, and really like it).