S & W mainspring M19

T B Good · September 25, 2010, 08:12 PM

I bought a used M19 and when I went shooting I had many light primer strikes. When I arrived home I found that the main spring tension screw was very loose. My question is: how tight should the tension screw be?

oldcspsarge · September 25, 2010, 08:30 PM

It should be screwed all the way in. It is NOT intended to be a trigger pull adjustment. If the DA trigger pull is too hard, but a replacement spring kit from Brownell's designed to lighten the trigger pull but designed to still give adequate primer strike.

**44 AMP** · September 25, 2010, 09:15 PM

The head of the screw should be flush with the frame. It should not "need" to be screwed in any further for reliable ignition. IF it does need to be screwed in further for reliable ignition, you should have the gun checked by a smith (who knows what he is doing, like a factory warranty station smith), as it could be something else (including the spring) that needs attention. It may be ok, and just need a turn more than usual on the strain screw, but having it checked by a competent pro is the safe bet. A few bucks and a little time beats the hell out of not having the gun fire when/if you really need it.

The important thing is reliable ignition, not trigger pull weight. If the pull is still to much for your tastes after you are sure everything is ok, then replacement springs, and/or a trigger job is the way to go.

**Mike Irwin** · September 25, 2010, 11:02 PM

It should be snugged down good and tight.

If it's not, firing the gun will cause it to eventually walk out.

Sport45 · September 25, 2010, 11:04 PM

I believe oldcspsarge is correct. It should be screwed in fully. Any adjustments made to the tension by a competent 'smith would be made by filing the screw to make it shorter. Loosening the screw leaves it free to loosen itself furthur in service.

Someone used to sell an "adjustable" strain screw that had serrations on the end that acted to keep it from backing out. Teddy Jacobson, maybe?

T B Good · September 26, 2010, 02:00 AM

Thanks everyone.

rodfac · September 26, 2010, 07:00 AM

I've never had a Smith tension screw back out...but I have re-tightened one on a M-66 that my son was having light having problems with. Re-tightening cured his light primer strikes. I'd recommend you try that first, and use some Loc-tiite on the threads as well.

If that doesn't do it, call S&W's service dept. They may replace or fix what is necessary for free.

Regards, Rodfac

lmccrock · September 26, 2010, 07:36 AM

I have a Model 10 that had some ignition issues. The internals were gummed up enough that the hammer fall was impeded. Cleaning it out made it 100%. Umm..the gunsmith showing me it needed to be cleaned out......

That said, same smith said to change the spring to change the tension. The screw could be used to experiment a little, but it should not be loose.

Lee

T B Good · September 28, 2010, 05:30 PM

I went shooting yesterday. When I went to clean today, it appears the screw backed out a little. Opinion please, do you think lock tite will hold it?

jtmo3 · September 29, 2010, 07:48 AM

Clean the screw and frame threads and use a little blue loctite.

Sport45 · September 29, 2010, 08:40 AM

Quote:

I went shooting yesterday. When I went to clean today, it appears the screw backed out a little.

Was it tight before you went shooting? It shouldn't require any type of thread locker. In fact, I normally put a little oil on it when re-assembling. If it's tight, the little bit of bolt stretch it has should hold it in place.

If you want to "lock" it and don't have the blue stuff mentioned above, a dab of clear nail polish from your wife's cabinet will do in a pinch.

T B Good · September 29, 2010, 06:01 PM

Thanks everyone.

I can only shoot once a week right now so I don't clean till the week end, so I have to put some lock tite (I still need to but it) after I clean.

1911rocks · September 29, 2010, 06:18 PM

Sport45 was absolutely correct. The perscribed method 30 yrs ago per S&W was
1) remove screw
2) degrease screw and threads
3) Segrease threads in Grip Frame
4) Replace screw and tighten till it's "tight"
5) Place frame in appropriate Frame size Frame fixture
6) With a properly fitting screwdriver (Hollow Ground Blade) Place considerable tension on screw.
7) while tensioning screw, with a plactic mallet rap screwdriver handle oundly (1) time ONLY

September 25, 2010, 08:12 PM	#1
T B Good Member Join Date: May 20, 2008 Posts: 95	S & W mainspring M19 I bought a used M19 and when I went shooting I had many light primer strikes. When I arrived home I found that the main spring tension screw was very loose. My question is: how tight should the tension screw be?

September 25, 2010, 09:15 PM	#3
44 AMP Staff Join Date: March 11, 2006 Location: Upper US Posts: 28,832	The head of the screw should be flush with the frame. It should not "need" to be screwed in any further for reliable ignition. IF it does need to be screwed in further for reliable ignition, you should have the gun checked by a smith (who knows what he is doing, like a factory warranty station smith), as it could be something else (including the spring) that needs attention. It may be ok, and just need a turn more than usual on the strain screw, but having it checked by a competent pro is the safe bet. A few bucks and a little time beats the hell out of not having the gun fire when/if you really need it. The important thing is reliable ignition, not trigger pull weight. If the pull is still to much for your tastes after you are sure everything is ok, then replacement springs, and/or a trigger job is the way to go. __________________ All else being equal (and it almost never is) bigger bullets tend to work better.

September 25, 2010, 11:02 PM	#4
Mike Irwin Staff Join Date: April 13, 2000 Location: Northern Virginia Posts: 41,389	It should be snugged down good and tight. If it's not, firing the gun will cause it to eventually walk out. __________________ "The gift which I am sending you is called a dog, and is in fact the most precious and valuable possession of mankind" -Theodorus Gaza Baby Jesus cries when the fat redneck doesn't have military-grade firepower.

September 25, 2010, 11:04 PM	#5
Sport45 Senior Member Join Date: May 25, 1999 Location: Too close to Houston Posts: 4,196	I believe oldcspsarge is correct. It should be screwed in fully. Any adjustments made to the tension by a competent 'smith would be made by filing the screw to make it shorter. Loosening the screw leaves it free to loosen itself furthur in service. Someone used to sell an "adjustable" strain screw that had serrations on the end that acted to keep it from backing out. Teddy Jacobson, maybe? __________________ Proud member of the NRA and Texas State Rifle Association. Registered and active voter.

September 26, 2010, 07:00 AM	#7
rodfac Senior Member Join Date: January 22, 2005 Location: Kentucky Posts: 3,623	I've never had a Smith tension screw back out...but I have re-tightened one on a M-66 that my son was having light having problems with. Re-tightening cured his light primer strikes. I'd recommend you try that first, and use some Loc-tiite on the threads as well. If that doesn't do it, call S&W's service dept. They may replace or fix what is necessary for free. Regards, Rodfac __________________ Cherish our flag, honor it, defend it in word and deed, or get the hell out. Our Bill of Rights has been paid for by heros in uniform and shall not be diluted by misguided governmental social experiments. We owe this to our children, anything less is cowardice. USAF FAC, 5th Spl Forces, Vietnam Vet '69-'73.

September 25, 2010, 08:30 PM	#2
oldcspsarge Senior Member Join Date: January 11, 2008 Location: Rocky Mountains Posts: 441	It should be screwed all the way in. It is NOT intended to be a trigger pull adjustment. If the DA trigger pull is too hard, but a replacement spring kit from Brownell's designed to lighten the trigger pull but designed to still give adequate primer strike.

September 26, 2010, 02:00 AM	#6
T B Good Member Join Date: May 20, 2008 Posts: 95	Thanks everyone.

September 26, 2010, 07:36 AM	#8
lmccrock Senior Member Join Date: April 23, 2007 Location: Red Rock. TX Posts: 820	I have a Model 10 that had some ignition issues. The internals were gummed up enough that the hammer fall was impeded. Cleaning it out made it 100%. Umm..the gunsmith showing me it needed to be cleaned out...... That said, same smith said to change the spring to change the tension. The screw could be used to experiment a little, but it should not be loose. Lee

September 28, 2010, 05:30 PM	#9
T B Good Member Join Date: May 20, 2008 Posts: 95	I went shooting yesterday. When I went to clean today, it appears the screw backed out a little. Opinion please, do you think lock tite will hold it?

September 29, 2010, 07:48 AM	#10
jtmo3 Member Join Date: March 22, 2007 Posts: 47	Clean the screw and frame threads and use a little blue loctite.

September 29, 2010, 06:01 PM	#12
T B Good Member Join Date: May 20, 2008 Posts: 95	Thanks everyone. I can only shoot once a week right now so I don't clean till the week end, so I have to put some lock tite (I still need to but it) after I clean.

September 29, 2010, 06:18 PM	#13
1911rocks Senior Member Join Date: September 9, 2006 Posts: 424	Mainspring Tension Screw adjsutment Sport45 was absolutely correct. The perscribed method 30 yrs ago per S&W was 1) remove screw 2) degrease screw and threads 3) Segrease threads in Grip Frame 4) Replace screw and tighten till it's "tight" 5) Place frame in appropriate Frame size Frame fixture 6) With a properly fitting screwdriver (Hollow Ground Blade) Place considerable tension on screw. 7) while tensioning screw, with a plactic mallet rap screwdriver handle oundly (1) time ONLY