Because options in 9mm ammunition are readily available today, that did not exist, when the Hi Power and it’s springs were designed.  Hi Power Clones and variants, including the Kareen Mark II and Mark III, the Arcus 94, and Arcus 98DA, have enhanced slides compared to the original FN/Browning Hi Power design, outweighing the original by approximately 3 ounces.  The idea was to build a Hi Power variant that would tolerate the abuse of higher than standard pressure ammunition ( +P or +P+ ).  However, in order to successfully cycle that beefier slide with standard pressure ammunition, the Hi Power’s standard 17 lb recoil spring was then lightened to a 15 lb spring.  So while the construction of your Hi Power may hold up to whatever hotter 9mm ammunition comes along next, the felt recoil produced may be a bit much with the lighter 15 lb recoil spring.    


15lb Recoil Spring – This is the standard recoil spring for the Hi Powers named above, and generally works well with all Standard Pressure ammunition.  Special Note: Use of 9mm ammunition with bullet weights of less than 115 gr or particularly light reloads, may cause “short cycling” in your Hi Power and is not recommended - that is, the ammunition may be a bit too underpowered to fully cycle the slide, causing malfunctions.   


17lb Recoil Spring – This heavier recoil spring may help protect you and your firearm if you choose to shoot ammunition of higher than standard pressure.  However, the use of high pressure ammunition, that being +P and +P+, is not recommended by the manufacturer of your Hi Power, and BHSpringSolutions does NOT recommend that you do so.  Some heavier bullet weight standard pressure ammunition (such as 147 gr JHP) will function reliably using the 17 lb spring and may slightly reduce recoil.  However: Special Note: Some standard pressure 9mm ammunition may cause “short cycling” when using the 17 lb recoil spring – that is, the ammunition may be a bit too underpowered to fully cycle the slide, causing malfunctions. 

(In other words, do not consider the 17 lb spring to shoot 115 gr FMJ budget/target ammunition.)