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270105SP187 Technical Profile    Application: Target/Tactical

Barrel Bore Diameter: 0.270" 6.860 mm The diameter of the barrel from land to land.
Barrel Groove Diameter: 0.277" 7.040 mm The diameter of the barrel from groove to groove.
Bullet Weight: 105gr 6.8g Bullets are guaranteed to weigh within 0.25% of the stated weight.
Bullet Length: 1.16" 29.450 mm
Secant Ogive Length: 0.51" 13.079 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" 0.686 mm
Min Bullet Protrusion: 0.59" 14.950 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: 0.79" 20.000 mm
Bullet conforms to CIP and SAAMI for magazine length. Check the magazine length of your rifle for suitability with this bullet.
Maximum M/V: 3400fps 1,036 m/s If the maximum muzzle speed is exceeded, dynamic stabilty problems may be encountered.
       
Twist: Sg = 1.5: 9.0" / 240 mm 35.0 Cal. in length The twist required to give a calculated Sg 1.5
Minimum Twist: 10" / 254 mm 37.0 Calibers in length The twist required for stable flight and the best long range tractability more than 450 yds or 420 m.
       
Calculated Ballistic Coefficient - G1 profile  
BC = 0.391 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 = 0.352 2300 fps to 1200 fps 701 m/s to 366 m/s
BC = 0.256 1200 fps to 0 fps 366 m/s to 0 m/s

Suitable Cartridges, with consideration of the above specifications:

270 Win, 270 GS, 6.8 SPC

NOTES

A Gyroscopic Stability (Sg) greater than 1.2 is required for SP bullets. For use under 450yds/420m an Sg of up to 1.5 or even greater can be used. For distances beyond 450yds/420m, 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.