17/223 FA-T 210 (AMA 4.32x45) (SBR)

Research notes

Dummy loading with brass case, GMCS bullet and blackened primer. Case filling is an inert salt to simulate the correct weight.

The US Army instituted the Serial Bullet Rifle (SBR) Program in 1965 in an attempt to develop a high velocity, low recoil impulse round that would share the same positive characteristics with flechettes, bur without the associated negatives such as erratic performance and high manufacturing costs. Colt provided six M16 rifles chambered in .17cal. The idea was to launch three projectiles in a very short period of time, with what would feel like a single recoil impulse. Some of these guns were modified with a ‘burst’ setting.

Bullet weight was 27.5gr. with a velocity of 3 700 fps (1 100 m/s) and unless the bullet is completely stable when leaving the muzzle, it will disintegrate. As a result, later on GMCS bullets were developed. Tracer ammunition was also developed. Severe bore erosion and excessive chamber pressures (50 000 psi) led to the program being suspended.

In the late 1960’s and early 1970’s there was renewed interest in launching a .17 cal projectile that was held in a full caliber sabot. The project did not prove accurate enough. During the early and mid 1970’s Rodman Laboratory at Rock Island Arsenal worked on a .17cal rifle. More ammunition was manufactured to test barrel erosion and rifling configurations.