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400477SP285 Technical Profile

Bore Diameter: 0.390" 9.910 mm The diameter of the barrel from land to land.

Groove Diameter: 0.401" 10.180 mm The diameter of the barrel from groove to groove.

Bullet Weight: 477gr 30.9g Bullets are guaranteed to weigh within 0.25% of the stated weight.

Bullet Length: 2.48" 62.900 mm

Ogive Length: 1.51" 38.276 mm These dimensions are critical to consistent external ballistic performance and are held constant to within 0.005 mm (0.0002")

Meplat Diameter: 0.04" 0.991 mm

Min Protrusion: 1.61" 40.990 mm Add the case length to these numbers to determine the maximum and minimum cartridge overall length that is possible with this bullet.

Max Protrusion: 2.05" 52.000 mm

Bullet does not conform to CIP and SAAMI for magazine length. Check the magazine length of your rifle for suitability with this bullet.

Max Launch Speed: 3400fps 1,036 m/s If the launch speed is exceeded, dynamic stabilty problems may be encountered

Minimum Twist: 10" 25.6 Calibers in length The slowest twist required for stable flight and the best long range tractability.

Sg = 1.5: Twist = 9.0" Twist = 23.9 Cal. in length The twist required to give a calculated Sg 1.5

Calculated Ballistic Coefficient - G1 profile

BC = 1.178 3400 fps to 2300 fps 1,036 m/s to 701 m/s BC values are calculated at standard Metro values and serve as a comparison between GSC bullets. Any comparison with the BC values of other manufacturers is not valid as there is currently no standard method in use between manufacturers.

BC = 1.027 2300 fps to 1200 fps 701 m/s to 366 m/s

BC = 0.741 1200 fps to 0 fps 366 m/s to 0 m/s

Suitable Cartridges, with consideration of the above specifications:

Experimental

NOTES

A Gyroscopic Stability (Sg) greater than 1.2 is required for SP bullets. For use under 500m, an Sg of up to 1.5 or even greater can be used. For distances beyond 500m the Sg can be decreased with a slower twist, but never less than 1.2 for GSC SP bullets.

Note that Sg increases as twist tightens. A 1:10" twist is tighter than a 1:12" twist within a given caliber only. Twist rates given in caliber lengths can be compared across calibers. Choose a bullet length best suited to your rifle twist and type of shooting. When a bullet is specified for a given twist rate, it can also be used in any twist that is tighter. Using it in a slower twist than specified is not advisable. Some experimentation will be required to determine exact drop tables for your equipment and location.

400477SP285 Technical Profile
400477SP285 Technical Profile
Bore Diameter:	0.390"	9.910 mm	The diameter of the barrel from land to land.
Groove Diameter:	0.401"	10.180 mm	The diameter of the barrel from groove to groove.
Bullet Weight:	477gr	30.9g	Bullets are guaranteed to weigh within 0.25% of the stated weight.
Bullet Length:	2.48"	62.900 mm
Ogive Length:	1.51"	38.276 mm	These dimensions are critical to consistent external ballistic performance and are held constant to within 0.005 mm (0.0002")
Meplat Diameter:	0.04"	0.991 mm
Min Protrusion:	1.61"	40.990 mm	Add the case length to these numbers to determine the maximum and minimum cartridge overall length that is possible with this bullet.
Max Protrusion:	2.05"	52.000 mm
Bullet does not conform to CIP and SAAMI for magazine length.			Check the magazine length of your rifle for suitability with this bullet.
Max Launch Speed:	3400fps	1,036 m/s	If the launch speed is exceeded, dynamic stabilty problems may be encountered
Minimum Twist:	10"	25.6 Calibers in length	The slowest twist required for stable flight and the best long range tractability.
Sg = 1.5:	Twist = 9.0"	Twist = 23.9 Cal. in length	The twist required to give a calculated Sg 1.5


Calculated Ballistic Coefficient - G1 profile
BC = 1.178	3400 fps to 2300 fps	1,036 m/s to 701 m/s	BC values are calculated at standard Metro values and serve as a comparison between GSC bullets. Any comparison with the BC values of other manufacturers is not valid as there is currently no standard method in use between manufacturers.
BC = 1.027	2300 fps to 1200 fps	701 m/s to 366 m/s
BC = 0.741	1200 fps to 0 fps	366 m/s to 0 m/s
Suitable Cartridges, with consideration of the above specifications:

Experimental


NOTES
A Gyroscopic Stability (Sg) greater than 1.2 is required for SP bullets. For use under 500m, an Sg of up to 1.5 or even greater can be used. For distances beyond 500m the Sg can be decreased with a slower twist, but never less than 1.2 for GSC SP bullets.

Note that Sg increases as twist tightens. A 1:10" twist is tighter than a 1:12" twist within a given caliber only. Twist rates given in caliber lengths can be compared across calibers. Choose a bullet length best suited to your rifle twist and type of shooting. When a bullet is specified for a given twist rate, it can also be used in any twist that is tighter. Using it in a slower twist than specified is not advisable. Some experimentation will be required to determine exact drop tables for your equipment and location.