Post by Bob Reed on Apr 12, 2024 9:07:23 GMT -5
Hello,
The below is for Standard Pressure 9mm Ammunition - I don't use lite-target loads or any +P ammo in my Automatic Pistols and if I did use +P, then I'd for sure stay with 32 Lb. Mainsprings and 18.5 Lb. Recoil Springs (for 9mm) and I actually have a good stock of BHSS 18.5 Lb. Recoil Springs on hand in case of maybe having to resort to using warmer-loaded 9mm ammo for whatever reason...
Recoil Springs: I don't think the extra 1.5 Lbs. of added spring strength increases the slide's return velocity enough to hurt anything by using an 18.5 Lb. vs. a 17 Lb. Recoil Spring - and if using less than a 30 Lb. Mainspring, then I believe using an 18.5 Lb. Recoil Spring is the better choice.
Mainsprings: I know 26 Lbs. was FN Factory Spec from 1935 to sometime Post 1972, but still, I personally won't go under 30 Lbs. (and until BHSS came along, I converted all the older BHPs I worked on to Factory 32 Lb. Mainspring/Hammer Strut Assy.) - the 30 & 32 Lb. Mainsprings just offer an extra amount of (needed? I believe so) aid by slowing down the unlocking process and eliminates a lot of extra shock/recoil that otherwise gets transferred to frame & slide when the slide smacks against the frame at the end of its rearward travel.
Firing Pin Retaining Plates (there's two types - Pre-1994 and Post 1993) the Pre-1994 has the original, small radius that offers more resistance during unlocking - and the large radius, Post 1993 FP Retaining Plate that was introduced with the .40 caliber BHP was mainly designed to off-set the .40s heavy 20 Lb. Recoil Spring when hand-cycling the slide when the hammer is forward/down. So, for example, using a Pre-1994 FP Retaining Plate along with a BHSS 30 Lb. Mainspring makes a good combination, and honestly, the 30 Lb. Mainspring is probably plenty heavy when using either of the FP Retaining Plates on a 9mm HP. That said, I personally won't use less than a 32 Lb. Mainspring on the .40 caliber BHP. (Note: Post 1993 - FN went to the large radius FP Retaining Plate on both the 9mm & .40 caliber BHP)
For the .40 caliber BHP and Std. PSI ammo - I don't believe one needs to go above the Factory 20 Lb. Recoil Spring Rating and should Not go below the Factory 32 Lb. Mainspring Rating.
Good Luck, Everyone.
PS: FN Factory Spec for the 17 Lb. recoil spring when new, is to have a free length of 110-115mm. FN also advises replacing the recoil spring when its free length is no-more than 105mm (but since springs are cheap and being extra cautious, I replace them before they drop to 105mm in free length). All my FN Factory & BHSS 17 Lb. Recoil Springs measure at the maximum free length. Remember, the smaller end coil always goes to the guide rod. - Bob
The below is for Standard Pressure 9mm Ammunition - I don't use lite-target loads or any +P ammo in my Automatic Pistols and if I did use +P, then I'd for sure stay with 32 Lb. Mainsprings and 18.5 Lb. Recoil Springs (for 9mm) and I actually have a good stock of BHSS 18.5 Lb. Recoil Springs on hand in case of maybe having to resort to using warmer-loaded 9mm ammo for whatever reason...
Recoil Springs: I don't think the extra 1.5 Lbs. of added spring strength increases the slide's return velocity enough to hurt anything by using an 18.5 Lb. vs. a 17 Lb. Recoil Spring - and if using less than a 30 Lb. Mainspring, then I believe using an 18.5 Lb. Recoil Spring is the better choice.
Mainsprings: I know 26 Lbs. was FN Factory Spec from 1935 to sometime Post 1972, but still, I personally won't go under 30 Lbs. (and until BHSS came along, I converted all the older BHPs I worked on to Factory 32 Lb. Mainspring/Hammer Strut Assy.) - the 30 & 32 Lb. Mainsprings just offer an extra amount of (needed? I believe so) aid by slowing down the unlocking process and eliminates a lot of extra shock/recoil that otherwise gets transferred to frame & slide when the slide smacks against the frame at the end of its rearward travel.
Firing Pin Retaining Plates (there's two types - Pre-1994 and Post 1993) the Pre-1994 has the original, small radius that offers more resistance during unlocking - and the large radius, Post 1993 FP Retaining Plate that was introduced with the .40 caliber BHP was mainly designed to off-set the .40s heavy 20 Lb. Recoil Spring when hand-cycling the slide when the hammer is forward/down. So, for example, using a Pre-1994 FP Retaining Plate along with a BHSS 30 Lb. Mainspring makes a good combination, and honestly, the 30 Lb. Mainspring is probably plenty heavy when using either of the FP Retaining Plates on a 9mm HP. That said, I personally won't use less than a 32 Lb. Mainspring on the .40 caliber BHP. (Note: Post 1993 - FN went to the large radius FP Retaining Plate on both the 9mm & .40 caliber BHP)
For the .40 caliber BHP and Std. PSI ammo - I don't believe one needs to go above the Factory 20 Lb. Recoil Spring Rating and should Not go below the Factory 32 Lb. Mainspring Rating.
Good Luck, Everyone.
PS: FN Factory Spec for the 17 Lb. recoil spring when new, is to have a free length of 110-115mm. FN also advises replacing the recoil spring when its free length is no-more than 105mm (but since springs are cheap and being extra cautious, I replace them before they drop to 105mm in free length). All my FN Factory & BHSS 17 Lb. Recoil Springs measure at the maximum free length. Remember, the smaller end coil always goes to the guide rod. - Bob
