pre model 10 2in problem

[srnotjr]

Hello I am new to this forum and need some help in diagnosing a problem with my M&P pre model 10 2in. SN# S 912xxx. Just got it and cleaned it . Lots of old grease and stuff in the frame. Completely cleaned and reassembled correctly. Empty the gun functions perfectly,timed, no end shake and a smooth DA pull.
At range, fired 1st round(38 rem wadcutter) ,then gun would not cycle. The cylinder would not turn unless you open up the cylinder ,which came out freely, and reclose it. Then another round and locks up again. All common causes of cyclinder binding checked, extractor rod loose,dirt under the star, hand,cylinder stop all negative. Happens with all types of ammo. Local gunsmith is stumped.

Any help would be appreciated. Thanks.

 

[Goblin]

Just for clarification, you can dry fire it more than six times and it functions correctly, right? Both single and double action?

 

[srnotjr]

Correct. It cycles with dry firing perfectly and only malfunctions after you fire a round. It cycles with a full cylinder normally and seems only under recoil to lock up. Cylinder stop goes up and down as it should.

 

[ken158]

Try replacing the cylinder stop spring.

 

[srnotjr]

ok. will try that.

 

[linde]

Correct. It cycles with dry firing perfectly and only malfunctions after you fire a round. It cycles with a full cylinder normally and seems only under recoil to lock up. Cylinder stop goes up and down as it should.

Is it possible you're dry firing by pointing down at the ground so gravity is holding the hand against the cylinder ratchet? If so, I would suspect the hand spring is not properly installed.

Russ

 

[VM]

srnotjr - did you pull the hand out of the trigger during disassembly and cleaning?
When reinstalling you must "reset" the hand torsion spring within the trigger.
There is info in the smithing section FAQ's I believe

 

[srnotjr]

pointing at sky or ground or level made no difference, no movement of cylinder . The hand springs back and forth cleanly. the hand was not removed from the the trigger and it rotates the cylinder when dry firing.Only under recoil does the cylinder not turn. you can really pull hard on the trigger or hammer and it still will not turn. Only after opening or releasing the cylinder latch (openit completely ie swing out) does the cylinder then rotate as it should.

 

[SAFireman]

pointing at sky or ground or level made no difference, no movement of cylinder . The hand springs back and forth cleanly. the hand was not removed from the the trigger and it rotates the cylinder when dry firing.Only under recoil does the cylinder not turn. you can really pull hard on the trigger or hammer and it still will not turn. Only after opening or releasing the cylinder latch (openit completely ie swing out) does the cylinder then rotate as it should.

Maybe the center pin (locks the cylinder in place) is dirty or gummed up?

 

[DCWilson]

Do the hammer and trigger return normally to their rest positions after a round is fired and the trigger released?

It's hard to visualize what might stop a cylinder's rotation other than a stuck hand, stuck cylinder stop or protruding firing pin.

 

[linde]

Maybe the center pin (locks the cylinder in place) is dirty or gummed up?

Excellent suggestion. There is a tapered block on the cylinder bolt and a pin on the cylinder hand that guides the hand away from the cylinder ratchet when the bolt is not completely closed.

In addition to checking for dirt, check the spring and plunger in the rear of the bolt to insure it's in place . . . I've had the plunger launch when removed.

Russ

edit to add: not sure that feature is present on the early post-WWII Model 10s . . . depends on when the hand with the pin was implemented.

 

[DWalt]

"edit to add: not sure that feature is present on the early post-WWII Model 10s . . . depends on when the hand with the pin was implemented."

This one would definitely have the cylinder stop spring and plunger behind the screw ahead of the trigger guard. I'd check to see if the springs on both the cylinder stop and hand are correctly installed.

 

[srnotjr]

Thanks for all the imput.

SAfirman, i am sure there is no junk there as i used 1/2 can of gun scrubber after the 2nd cleaning

linde..will check that

DWalt..sequence is cylinder stop,plunger,sping, screw.

DCwilson..once fired the hammer and trigger will not move move than 1/4inch back even if you let go of the trigger and hammer and try again.
the firing pin does not protrude.

 

[tputto]

Just a thought: have you tried pulling back on the cylinder latch on the jammed gun? If the bolt moves forward under recoil, it would lock up the gun by blocking the hammer. Is there proper spring tension on the center pin? Press down on its end in the rear of cylinder, there should be resistance and snappy return when pressure is released. If not, this may allow bolt to move under recoil.

 

[tlay]

Is the cylinder stop still engaged when you try to pull the trigger? Try slipping a feeler guage between the cylinder and stop to see if that frees it up.

 

[linde]

Excellent suggestion. There is a tapered block on the cylinder bolt and a pin on the cylinder hand that guides the hand away from the cylinder ratchet when the bolt is not completely closed . . .

Here are two types of K-frame cylinder bolt and hand combinations. Note the pair on the right has a pin on the hand and the bolt has a tapered block on the bottom.

Just a thought: have you tried pulling back on the cylinder latch on the jammed gun? If the bolt moves forward under recoil, it would lock up the gun by blocking the hammer. Is there proper spring tension on the center pin? Press down on its end in the rear of cylinder, there should be resistance and snappy return when pressure is released. If not, this may allow bolt to move under recoil.

Excellent suggestion. Here is an example of what tputto describes . . . it happens to be a J-frame that was open on the bench but the principle is the same. Note how the cylinder hand is being pulled away from the cylinder.




If the cylinder bolt is free to move rearward, check to insure the small spring is properly installed on the center pin so the pin is pushing firmly against the bolt.


Russ

 

[DWalt]

About 3-4 years ago, I had a similar problem on a Model 28. Tore it apart, cleaned everything thoroughly, checked everything, and couldn't find anything unusual. But that didn't resolve the problem. Then one day it magically fixed itself with no further mishaps. I never knew what caused it. But shortly thereafter I sold the Model 28, as I didn't trust it anymore.

 

[srnotjr]

Thanks to all for the awesome suggestions! I will let you how things turn out when i pick up revolver from gun smith this weekend. He is having another guy look at it .
Really great stuff, Thanks again.
Brian

 

[younggun22]

are we shooting reloads or factory ammo?

 

[srnotjr]

factory ammo only. remmington wadcutters,horniday 38 jhp,and blazer 158 gr lead. no +P .