4506 Decocking to safe while firing ? Help **

SemperFuzz · Mar 26, 2011

So i got my 4506 back after a full tune up all springs replaced to factory new and all new S&W Mags.

When firing i had multiple problems when firing the slide would go home and the decocker safety would decock and drop into safe mode when shooting single action.

I would guess the decocker safety lever has a spring in there that is too loose or? With the slide locked back the lever does feel quite loose up and down i can assume the recoil slamming home is dropping the decocker down. When the slide is closed the safety decocker feels tight.

Bringing back to the gunsmith but wanted some input from anyone that knows whats going on, never had this problem when i carried the gun years ago.

Tbojo · Mar 26, 2011

My 4506 did this and the fix was replacing the recoil spring. I suspect that you have a new one if all the springs were replaced, this can also happen if the wrong spring is installed for the safety position plunger, sometimes the spring that retains the safety lever is switched with the position plunger by mistake -- they look the same but the plunger spring is stiffer. Good luck!

Fastbolt · Mar 26, 2011

Unless your manual safety body plunger spring suddenly broke (possible, but I've never heard of it happening), the common cause for the manual safety levers to decock during recoil is for someone to have unintentionally switched the ambi safety lever plunger spring for the decocker body spring. Not an uncommon mistake for someone to make during a moment of inattention and mixing up the 2 springs. Sometimes someone may even lose the body plunger spring and grab an extra ambi lever spring by mistake.

As was mentioned, the decocker body plunger spring is much (noticeably) stiffer than the ambi lever plunger spring. It's extra tension can be noticed pretty quickly when trying to compress the spring between thumb & index finger. A new ambi lever spring is painted light blue, while the decocker body spring is unpainted.

The round head plunger and heavy spring on the left is the decocker body plunger & spring ... and the cylindrical plunger with flat head and lighter spring on the right is the ambi lever spring.

Whoever disassembled the slide probably switched the springs.

I've also seen where someone switched the plungers, too, and the wrong plunger in the decocker body makes for a nasty decocking effort and marks up the smooth beveled surface inside the slide's recess where the round headed plunger rides.

SemperFuzz · Mar 27, 2011

Awesome stuff thanks guys and Fastbolt for the pictures these are great! i am just emailed the info to my gunsmith and will bring my baby in on Monday for some warranty work.

I hope that is what it is as i was really stressing out thinking what the Heck i cant carry this on duty ! And i dont want to go back to a Glocken-Speil either ahahahah

I will let you guys know what happens soon

SemperFuzz · Mar 27, 2011

Are these the S&W Parts i order here? I thought i had them from the WOLFF spring performance pack but i want to get the S&W factory ones. How many of each piece do i order? Thanks

Parts Listing for Model: M4506
03 106020000 $0.51 AMBI M/S LEVER PLG SPR
04 230150000 M/S BODY PLUNGER/LEVER PLUNGER $0.78

04 237750000 $0.78 R3 AMBI M/S LEVER PLUNGER
05 105770000 AMBI M/S BODY PLUNGERSPR
$0.78

SemperFuzz · Mar 30, 2011

Well i ordered my Springs from S&W and i got the Blue spring part #
106020000 called the SA/LEV DT SPRG REV NEW

I received the Round head plunger part # 23015000 shown in left picture above by Fastbolt.

I then asked for the Ambi M/S body plunger spring Part # 10577000 assuming it was the stiff spring pictured on the left and the sent me a gigantic black bracket thing? WTH? picture shown below. What the hell is this thing? i dont see this on my 4506.

Can someone please tell me what S&W part # is the stiff spring i need to order and if S&W was wrong in this part i paid overnight shipping to get these springs that Fastbolt posted and now i am out the Stiff heavy spring?

Hep Me !

Fastbolt · Mar 30, 2011

Oops.

They sent you a side plate assembly. Hopefully it's for the .45 frame.

It's probably one of the following parts:
Part # 106990000 $6.84 X SIDEPLATE ASSY
Part # 108600000 $6.84 R1 SIDEPLATE ASSY

Not a bad part to have as a spare, though. It's located under the left grip panel. You can see the top edge of it running along under the upper left side of the left grip. The "tuning fork" part of the assembly snaps over the recessed head of the sear pin (left end), which positions the upper part of the assembly so the small outward angled plate can engage the slide stop lever plunger.

The side plate can require replacement if the "legs", or prongs (tuning fork), become tweaked or broken during improper grip installation, or if the pin part of the assembly becomes loose where it's staked to the flat "plate" part of the assembly.

You did indeed want this spring:
Part # 105770000 $0.78 AMBI M/S BODY PLUNGER SPR

SemperFuzz · Mar 30, 2011

S&W is overnighting me the correct stiff springs their fault, i dissasembled the decocking mechanism thanks to this nice video on you tube

YouTube - Smith & Wesson Mod 4506 advanced takedown Part 3

Well i did indeed have both wimpy lightweight springs installed in both spots. I found the stiff spring i had ordered from Numrichs and i installed that and installed the lightweight blue spring on the right side and WoW what a difference ! Nice and tight and not loose anymore. Heading to the range today will report back.

My removable thumb safety on the right does not have the flat clyindrical plunger shown in the picture Fastbolt posted as it came with one identical to the left side plunger. It goes in perfect and clicks into place when i slide the thumb safety back on.

My Gunsmith said he fixed my single action Trigger clicking problem and i thought he did too but now its doing it again ! Ahhhhh I'm going crazy.......

Thanks Fastbolt.

Fastbolt · Mar 30, 2011

There was an old style ambi lever plunger for a while. It had a "semi-rounded" appearance with a small flat head, but also has a shoulder. It was later changed to the cylindrical, non-shouldered version to increase strength. The old style flat plunger with the semi-rounded, shoulder head can be easily confused with the decocker body plunger at first glance, but the difference can be seen with a more careful look. The decocker body plunger must be the fully round headed plunger (NOT the old style lever plunger with a flat spot on the head), in order for smooth movement of the plunger head within the machined recess in the slide.

Unfortunately, the new style cylindrical plunger can only be used with a lever which has a wider space machined on the bottom side to accept it. Since the dimensions of the "head" of the old & new style ambi lever plungers are different, the machined recesses for them in the bottom of the levers are different, too.

The old style ambi lever plunger is the one in the middle of this picture:

The .45 lever also has an added bit of material on the bottom of the lever ... a "tab", so to speak ... which acts as a spacer to keep the manual safety assembly from shifting within the slide (which could potentially shift so that it impedes the freedom of movement of the firing pin during live-fire).

This picture shows a standard ambi lever (9/.40) on the left and a .45 ambi lever on the right, with the pin punch pointing to the added "tab" material. This .45 lever must be used in 9/.40 slides which have the optional spring-loaded, decock-only assembly in place of the standard manual safety assembly.

The ambi lever is a bit of an expensive part, small though it is ...

SemperFuzz · Mar 30, 2011

Just finished at the range and all is good. No problems at all with the gun decocking on its own. Thank you so much for the info my baby shoots great again. I did use a brand new plunger that matches pic 1 all is smooth and correct......

Fastbolt · Mar 31, 2011

Glad to hear it.

SemperFuzz · Apr 3, 2011

I took her apart again just to make sure and i did have the fully rounded head on the left and the item # 2 pic on the right side so i am still good to go. Feels good to be able to do little gunsmithing myself being the non-mechanical type. Thanks to you tube and the Forums here. ooooRah ! and now i know how to change my firing pin spring too Sweeet.........

4506 Decocking to safe while firing ? Help **

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