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Old 07-11-2018, 08:04 PM
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LLOYD17 LLOYD17 is offline
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Default Pre-war N Frame DA hitch

I've got a pre-war N Frame that has a bit of an issue in DA. SA is perfectly fine, but when cycling DA, right at the beginning of the trigger pull there is a hitch that takes varying degrees of force to overcome. Sometimes the hitch is nearly imperceptible and other times the trigger and hammer get completely hung up in the hand-off and jams.

I think I've narrowed it down to an issue with the sear I believe but I'm not sure if it's an issue of being too short or just some grittiness that keeps it from fully resetting. Since the DA pull seems fine a points and degrades at other times to full jam, perhaps the sear is getting hung up. I have sonic cleaned the hammer and trigger but can do more soaking if needed.

Since I'm a self-taught hobbyist, I just did a bunch of swapping parts to see what happened. First I tried a 455 MK II but those parts didn't work at all (I thought it was only the TL and the 1917 that were drastically different). Then I used an early 30's 1926.

455 MK II action


1926 action


Problem action


The two with their original parts still installed


Where the hang-up or hitch occurs


just the 1926 hammer swapped in


just the 1926 trigger swapped in


Conclusions:
1. Swap in 1926 hammer only - DA is great
2. Swap in 1926 trigger only - worse DA issues, the sear is resting on the trigger and completely binds up nearly every pull.

The difference between the two sears is evident with the smaller curved one being the one with issues. (1926 on the left)




The area on the triggers that engage the sear are different between the two guns with the 1926 being about 0.008(ish) thicker. (1926 on the left)


>>>Is this just a case of replacing the sear and having it fitted to the original trigger or is a new trigger also needed?

Thanks!


The rest of the gun glamour shot
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Old 07-11-2018, 08:26 PM
Toolguy Toolguy is offline
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Oftentimes in a situation like this, a slight amount of fitting will cure the problem. It's one of those things best done with gun in hand to see exactly what is doing what, rather than guessing about it long distance.
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Old 07-11-2018, 08:36 PM
john323 john323 is offline
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Quote:
Originally Posted by LLOYD17 View Post
I've got a pre-war N Frame that has a bit of an issue in DA. SA is perfectly fine, but when cycling DA, right at the beginning of the trigger pull there is a hitch that takes varying degrees of force to overcome. Sometimes the hitch is nearly imperceptible and other times the trigger and hammer get completely hung up in the hand-off and jams.

I think I've narrowed it down to an issue with the sear I believe but I'm not sure if it's an issue of being too short or just some grittiness that keeps it from fully resetting. Since the DA pull seems fine a points and degrades at other times to full jam, perhaps the sear is getting hung up. I have sonic cleaned the hammer and trigger but can do more soaking if needed.

Since I'm a self-taught hobbyist, I just did a bunch of swapping parts to see what happened. First I tried a 455 MK II but those parts didn't work at all (I thought it was only the TL and the 1917 that were drastically different). Then I used an early 30's 1926.

455 MK II action


1926 action


Problem action


The two with their original parts still installed


Where the hang-up or hitch occurs


just the 1926 hammer swapped in


just the 1926 trigger swapped in


Conclusions:
1. Swap in 1926 hammer only - DA is great
2. Swap in 1926 trigger only - worse DA issues, the sear is resting on the trigger and completely binds up nearly every pull.

The difference between the two sears is evident with the smaller curved one being the one with issues. (1926 on the left)




The area on the triggers that engage the sear are different between the two guns with the 1926 being about 0.008(ish) thicker. (1926 on the left)


>>>Is this just a case of replacing the sear and having it fitted to the original trigger or is a new trigger also needed?

Thanks!


The rest of the gun glamour shot
Looks like the pickup on the original trigger needs to be fitted. Could also break the edge where it comes in contact with the sear. Use a diamond hone.

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Old 07-11-2018, 10:31 PM
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Just like you, I'm an 'advanced amateur'.
Even though there were some changes in design, most of them were for very slight enhancements in feel or improvements in cost. Most pre-war long action parts can be interchanged with minor fitting required in some cases.
I've found a lot of DA 'hitches' were caused by mainspring strain screw issues.
Beyond that, as mentioned above, stoning the dragging leading edges often fixes the DA feel.
I've also found cases where the mainspring has been replaced and the 'fingers' on the stirrup end bind. A little grinding fixes this. If you ever swap in a Wolfe mainspring in a pre-war N, this is a must.
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Old 07-15-2018, 07:54 PM
Hondo44 Hondo44 is offline
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I would put all parts back in their original guns.

Then I would do some observation trouble shooting. The photo of the original gun with hammer at the point of the 'hitch' is good. Now locate the hammer(s) of one or both of the other two guns at the same position in the cycle and compare them to the problem gun.

You should be able to identify what's the difference in parts relationships in the working guns compared to the gun that binds. That will indicate where fitting is required or if there's a part that needs replacing.

If I change hammers in any gun, I always use the hammer fly (DA sear) from the original hammer. Because it's usually the source of the problem.
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Last edited by Hondo44; 07-15-2018 at 07:56 PM.
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Old 07-15-2018, 11:10 PM
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Quote:
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I would put all parts back in their original guns.

Then I would do some observation trouble shooting. The photo of the original gun with hammer at the point of the 'hitch' is good. Now locate the hammer(s) of one or both of the other two guns at the same position in the cycle and compare them to the problem gun.

You should be able to identify what's the difference in parts relationships in the working guns compared to the gun that binds. That will indicate where fitting is required or if there's a part that needs replacing.

If I change hammers in any gun, I always use the hammer fly (DA sear) from the original hammer. Because it's usually the source of the problem.
Theyíre all back together at this point. I havenít done the comparison, but that sounds like a good idea. Iíve got a couple other hammers enroute that just need the small parts I can play around with.

As to the other answers referring to real gunsmithing, Iíll definitely leave that to a professional as I would probably just make it worse.

Thanks for the help. Iím just glad it sounds like I can retain the hammer and trigger.
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Old 07-16-2018, 03:35 PM
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In the one photo where it looks to be about half cock, it looks like the bottom of the hammer is interfering with the edge of the trigger, just where the hammer foot inserts into the u shape of the trigger. If that is the case, do not file or stone either part!!! It will only give you a short throw feel and mess up the entire action.

Don't ask how I know this!!! I would guess you need a new sear installed as that one is worn, BUT, like Toolguy said, it is difficult to determine cause without gun in hand and careful observation. Especially from pictures.
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Old 07-16-2018, 07:23 PM
2152hq 2152hq is offline
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I kinda get lost in all the pictures,,but they are beautiful photos and show a lot.

In the pic: 'Where the hang-up or hitch occurs'
The DA sear is kicked too far out.
The trigger has not raised the hammer far enough by using the DA sear. That is allowing the under side of the hammer SA sear notch and the SA sear edge on the trigger to come in contact with each other and bind.

To pull the DA sear back in a tiny amt just to see if that is the problem,,with the hammer down/forward, depress the DA sear against it's spring pressure and insert a shim in between it's upper edge and the hammer itself. This is above the sear pivot point. That will push the sear down instead of being kicked out so far.
A couple strips of paper may do it, or a very thin shim of something like a business card is all that's needed. That may even be too much.

Once the shim(s) in place,,cycle the action again with the side plate off as in the same photo and carefully watch for the same interterence,,or not.
The upper surface of the trigger,,the pad, should lift the hammer farther back so the lower surface (SA sear) can clear the hammer w/o interfering with DA hammer motion at all.

If that's the problem. You can 'fix' the orig DA sear with a simple stake mark in that upper edge to drive a burr outward. That takes the place of the shim you used to test drive the idea.
The sear is hard and small,,tough to hold on to and not easy to upset. But careful work and it can be done.
The other way is to actually soft solder a small metal shim to that area of the sear and trim it neatly.
The shim takes no side load so a soft soldered joint works fine. An electric soldering gun works fine for the job and you're done in a few seconds. No heat damage to the sear. Hold the other end in the vise jaws to be sure is OK.
A little final fit may be necessary. Don't loose that tiny spring underneath the sear!

That's my take on the problem from the pics and a way to fix it using the orig part.
Just from what I see in the pics.
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Old 07-16-2018, 08:05 PM
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I agree with 2152hq. The angle at the top of the sear where it engages the hammer looks off a bit. I circled the angle in the photo. You can see the small gap at the back of the top edge. The second picture shows where the shim would be needed and the direction the bottom of the sear needs to be pushed. As previously stated, it's a minute amount of adjustment that is needed. (I also asked my daughter who is a mechanical engineer her opinion. She also agrees with 2152hq.) If you're adding a shim, it's a really, really small one.
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