7.5 FK Ammunition
7.5 FK calibre ammunition is a proprietary calibre designed and produced by FK BRNO Engineering s.r.o. This caliber was designed specifically to bridge the gap between standard handgun and carbine rifle calibers in terms of power, efficiency, range, and accuracy. While at the same time it’s compact enough to be used in a standard size automatic pistol with a 5-inch or 6-inch barrel, and when used in pistols with FK BRNO’s patented recoil attenuating system, it has recoil comparable with calibers with less than half the kinetic energy. The following are calculations of conventional ballistic data for the 7.5 FK cartridge.
F9: All copper monolithic wide meplat flat nose. This bullet is designed to create a wide and very deep permanent wound channel in addition to a very high dynamic shock effect. Accurate and effective for defence and medium game hunting up to 300 lbs to 100 yards, and dangerous game up to 500 lbs to 50 yards.
S95: Jacketed Hollow point made by Sierra bullets exclusively for FKB, it is designed to explode and shatter on impact. This bullet makes huge, but shallower wound channels than the other versions. Accurate and effective for defence and medium game hunting up to 100 lbs at 100 yards.
F5: All copper, monolithic nose discarding hollow point. The nose is designed to break off on impact, leaving a jagged 7mm meplat to create a large deep penetrating wound channel and a High Terminal Effect. Accurate and effective for defence and medium game hunting up to 200 lbs to 100 yards.
DYNAMIC SHOCK INDEX / BALLISTICS
FK BRNO has developed and patented the DSI ,an alternative computational system for measuring the efficacy of handgun cartridges. This methods measures the probability of instant incapacitation when compared to other calibres. The development was based extensive field testing and recent and historic war casualty data. It is calculated as follows:
Dynamic Shock Index [DSI] = Meplat Diameter x impact velocity – (1500-impact velocity) x sectional density
The following are examples of how some powerful versions of popular ammunition calibres score using muzzle velocity for illustrative purposes (as opposed to impact velocity) in comparison with the 7.5 FK:
|7.5 FK F9||FKB||0.236||1920||0.160||72.5|
|44 MAG 240 gr JHP||XT||0.255||1280||0.185||50|
|7.5 FK F5/S95||FKB||0.157||2000||0.150||47.1|
|357 Mag 125gr JHP||MT||0.248||1378||0.140||43.6|
|10 MM 180gr JHP||BB||0.236||1250||0.160||37.8|
|45ACP 185gr +P JHP||MT||0.255||1148||0.139||30.6|
|9 MM 124gr +P JHP||GD||0.208||1262||0.140||29.8|
|9 MM 135gr +P JHP||CD||0.157||1241||0.153||18.8|