Questions about BHP mainspring weights

[Trebor]

I have a CDNN FN Mk III and a ex-Isreali MK II/III hybrid.

I understand the current recoil spring weight is 32 pounds, correct? I find it very difficult to cock the hammer on both guns. My wife can't thumb the hammer back at all and has a very, very difficult time working the slide on either gun.

The Highpower fits her hand well. I'd like to install a lighter main spring/hammer spring and I have some questions:

1. The main spring is the same thing as the hammer spring on the BHP, correct?

2. What was the PREVIOUS standard spec weight for the main spring before FN switched to the 32 pound spring?

3. Why did they switch to a heavier spring? I've heard it was to ensure reliability with military ammo, but I don't know if that is really true. Any thoughts?

4. Is there any real reason NOT to switch to a lighter main spring? I'm not concerned with popping the primer on surplus "subgun" ammo or NATO spec ammo. I only shoot commercial 9mm ammo.

5. Any advice on what spring weight to switch to? My inclination is to go with whatever the PREVIOUS spec spring was before they went with the 32 pound spring.

6. Any other thoughts or advice. Remember, one of my primary purposes is to allow my wife to use the gun as it does fit her hand very well.

Thanks all,

Rob

 

[Stephen A. Camp]

Hello. I'd try a 28-lb spring first and see if that solved the problem.

Best.

 

[deezulsmoke]

I can suggest what worked for me. I replaced the recoil spring with a Wolff 18.5 recoil spring. This was done for two reasons. One was to take the oomph of some +P loads that I would be shooting. The other was to take up the slack from a ligher hammer spring. I changed the hammer spring in my MKIII to a 28 # Wolff spring. I also installed the firing pin spring that came with the recoil spring. The end result is a much light hammer pull with a recoil pull that is just a wee bit stiffer. I have shot target loads and +P+ loads with it, and it works well. The ligher hammer spring also lightened up the trigger pull appreciably. If you can see your way clear to take out the mag disconnect and do some light polishing on the trigger lever where it fits into the trigger, and where it contacts the side of the frame, along with some very light polishing of the sear and hammer, you will be rewarded with a much crisper easier to pull trigger. I would not suggest going with anything lighter than the 28# hammer spring for a carry gun.

Deez.
[email protected]

 

[Trebor]

Do you know if #28 was the original weight for the hammer spring by any chance?

 

[Bemo]

According to Mr. Camp's wonderful website, www.hipowersandhandguns.com
the mainspring was 26lbs. up until around 1975 when FN went to the now standard 32lb mainspring.

Hope that helps.

 

[StrikeEagle]

Just the last couple days I've been firing my 60's commercial BHP, and I've been loading up with some fantastically cheap Egyptian ammo. This ammo is kind of dirty, but accuracy is reasonable... but it has some wicked-hard primers. Every magazineful has a couple where I'll have to thumb back the hammer and try again. I can really see the genius of the 32-pound mainspring.

StrikeEagle

 

[Trebor]

just the last couple days I've been firing my 60's commercial BHP, and I've been loading up with some fantastically cheap Egyptian ammo. This ammo is kind of dirty, but accuracy is reasonable... but it has some wicked-hard primers. Every magazineful has a couple where I'll have to thumb back the hammer and try again. I can really see the genius of the 32-pound mainspring.

For a military service pistol I agree completely. For my use though, that spring is too heavy. I'm not going to be shooting any mil-surp through this gun and I'm confident that a somewhat lighter spring wont cause any problems. Course, I'll test it out throroughly before relying on it, just in case.

Edit: Just thought I'd add that I'm usually the first one to reccomend leaving springs at the factory setting. I'm convinced that must gun malfunctions are caused by the users mucking up perfectly good guns by lightening the springs, or turning back the set screw in S&W revolvers, installing shok buffs, etc.

In general, the factory specs are set for a reason and you shouldn't mess with them unless you have a good reason why. I figured I understood the reasoning in this case and decided it wasn't appropriate for my circumstnces. The other exception I make is for CZ springs, which generally are undersprung by the factory.

 

[MrAcheson]

As long as you aren't shooting +P through it, a lighter spring should be fine.