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264119SP253 Technical Profile    Application: Target / Tactical

Barrel Bore Diameter: 0.256" 6.500 mm The diameter of the barrel from land to land.
Barrel Groove Diameter: 0.264" 6.710 mm The diameter of the barrel from groove to groove.
Bullet Weight: 119gr 7.7g Bullets are guaranteed to weigh within 0.25% of the stated weight.
Bullet Length: 1.41" 35.800 mm
Tangent Ogive Length: 0.77" 19.476 mm These dimensions are critical to consistent external ballistic performance and are held constant to within 0.005 mm (0.0002")
Meplat Diameter: 0.03" 0.650 mm
Min Bullet Protrusion: 0.85" 21.570 mm Add the case length to these numbers to determine the maximum and minimum cartridge overall length that is possible with this bullet.
Max Bullet Protrusion: 1.06" 27.000 mm
Bullet does not conform to CIP and SAAMI for magazine length. Check the magazine length of your rifle for suitability with this bullet.
Maximum M/V: 3600fps 1,097 m/s If the maximum muzzle speed is exceeded, dynamic stabilty problems may be encountered.
       
Twist: Sg = 1.5: 7.0" / 174 mm 26.8 Cal. in length The twist required to give a calculated Sg 1.5
Minimum Twist: 7.5" / 190.5 mm 29.3 Calibers in length The twist required for stable flight and the best long range tractability more than 600 yds or 550 m.
       
Calculated Ballistic Coefficient - G1 profile  
BC = 0.619 3600 fps to 2400 fps 1,097 m/s to 732 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 = 0.535 2400 fps to 1200 fps 732 m/s to 366 m/s
BC = 0.380 1200 fps to 0 fps 366 m/s to 0 m/s

Suitable Cartridges, with consideration of the above specifications:

.264" / 6.5mm calibers subject to CIP / SAAMI bore groove and 7.5" twist

NOTES

A Gyroscopic Stability (Sg) greater than 1.2 is required for SP bullets. For use under 600yds/550m an Sg of up to 1.5 or even greater can be used. For distances beyond 600yds/550m, 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.