Some interesting reading about the development of GP90 from the Sig Forum:
"The Swiss actually began development of a new rifle and caliber to replace the Stgw 57 as early as the late 1960's. This is when upon analysis of the available .223, they determined that it did not meet the range requirements and was disregarded as a 200 meter round. Even though it was more or less conceded that 150 meters or less was the typical combat range for the modern infantryman, the Swiss still had their hearts and minds set on the 300 meter mark and already had plenty of target ranges (23,000 firing points) setup that way.
Of course, Switzerland is not alone in this. Americans were in fact the ones that insisted on the .308 as it was a marksman's cartridge, and of course, we see the lengths that match shooters will go to in order to use the .223 out to 600 yards! Hence, when procurement specifications were given for the new service rifle, one of the requirements was that it be as accurate as the Stgw57 at 300 meters.
The initial route pursued by the Swiss was to use a .22 caliber bullet but with and elongated case known as the 5.56mm Eiger. The end result was a case that was just about as long as the standard 7.5mm service round, but a bit thinner. However, end results of this experiment were poor power and accuracy.
In 1977, this project was halted and a larger bullet with a diameter of 6.35mm was selected instead. The diameter was subsequently changed again to 6.45mm. As a secondary option, the .223 round was still being modified and developed to see if there was any way to overcome the range and accuracy shortcomings of the 55 gr. .223. Up until the end of the 70's the direction seemed to be in favor of the 6.45mm round. However, all that changed in 1981 and it was ordered that all development go toward the 5.6mm round (Swiss designation for 5.56mm). The sudden change was a result of the development of the 62gr. SS109 round which actually seemed to perform better on penetration tests than the vaunted .308!
The Swiss of course, never content with what is available, proceeded to improve upon the SS109 round! The Swiss bullet is slightly heavier at 63 gr. and uses ball powder as a propellant. The designation for this ammunition is Gewehrpatrone 90, or GP90 for short. The penetration requirement for this round was a steel helmet and a half inch of pine at 400 meters and the round supposedly does this better than the standard NATO round. Considering that the standard SS109 round had to defeat a US helmet at 1100 meters, the Swiss round seems more than capable of the task at hand.
Tests of the GP90 show that the round is amazingly accurate, especially for a service military cartridge meant for general issue. At 300 meters, it is capable of 2" groups with half the rounds going into an area about 1" in size.
Folks, that's at minimum sub-MOA at 300 meters and at its best 1/3 MOA for a service rifle and ammo!"
I don't know if I can expect that kind of accuracy...even if I was good enough! But interesting anyhow.
I should have bought more of it than I did, I think!
__________________
"The Swiss actually began development of a new rifle and caliber to replace the Stgw 57 as early as the late 1960's. This is when upon analysis of the available .223, they determined that it did not meet the range requirements and was disregarded as a 200 meter round. Even though it was more or less conceded that 150 meters or less was the typical combat range for the modern infantryman, the Swiss still had their hearts and minds set on the 300 meter mark and already had plenty of target ranges (23,000 firing points) setup that way.
Of course, Switzerland is not alone in this. Americans were in fact the ones that insisted on the .308 as it was a marksman's cartridge, and of course, we see the lengths that match shooters will go to in order to use the .223 out to 600 yards! Hence, when procurement specifications were given for the new service rifle, one of the requirements was that it be as accurate as the Stgw57 at 300 meters.
The initial route pursued by the Swiss was to use a .22 caliber bullet but with and elongated case known as the 5.56mm Eiger. The end result was a case that was just about as long as the standard 7.5mm service round, but a bit thinner. However, end results of this experiment were poor power and accuracy.
In 1977, this project was halted and a larger bullet with a diameter of 6.35mm was selected instead. The diameter was subsequently changed again to 6.45mm. As a secondary option, the .223 round was still being modified and developed to see if there was any way to overcome the range and accuracy shortcomings of the 55 gr. .223. Up until the end of the 70's the direction seemed to be in favor of the 6.45mm round. However, all that changed in 1981 and it was ordered that all development go toward the 5.6mm round (Swiss designation for 5.56mm). The sudden change was a result of the development of the 62gr. SS109 round which actually seemed to perform better on penetration tests than the vaunted .308!
The Swiss of course, never content with what is available, proceeded to improve upon the SS109 round! The Swiss bullet is slightly heavier at 63 gr. and uses ball powder as a propellant. The designation for this ammunition is Gewehrpatrone 90, or GP90 for short. The penetration requirement for this round was a steel helmet and a half inch of pine at 400 meters and the round supposedly does this better than the standard NATO round. Considering that the standard SS109 round had to defeat a US helmet at 1100 meters, the Swiss round seems more than capable of the task at hand.
Tests of the GP90 show that the round is amazingly accurate, especially for a service military cartridge meant for general issue. At 300 meters, it is capable of 2" groups with half the rounds going into an area about 1" in size.
Folks, that's at minimum sub-MOA at 300 meters and at its best 1/3 MOA for a service rifle and ammo!"
I don't know if I can expect that kind of accuracy...even if I was good enough! But interesting anyhow.
I should have bought more of it than I did, I think!
__________________
