Trigger sticking at second stage after initial bolt operation?

[ChrisATX]

Hi good sirs,

I've noticed that occasionally, when feeding the first round of the magazine into the chamber, the trigger feels like it sticks at the beginning of the second stage. When the shooter goes to fire, there is no first stage pre travel, just a tiny bit of creep, then BANG. After manipulating the bolt to chamber the next round, the issue disappears and does not affect subsequent shots.

Additionally, cocking the striker and putting the safety on before opening the bolt and loading the magazine seems to prevent this, but it appears to be a potentially dangerous situation that needs to be remedied.

Thank you for any insight.

Chris

[Major Tom]

Triggers are inexpensive. Try another. Disassemble trigger and clean real good and clean where it contacts bolt mechanizim. Maybe use crocus cloth to polish contact areas.

[kcw]

I would agree that a disassembly and cleaning of the trigger/sear assembly is in order for starters. It sounds like the sear is not fully returning to its "resting" position. Possibly either the sear or trigger is binding on the sear pin due to crud/rust ect., or maybe a weak coil return spring?

[Devil Dog]

I would look at the sear return spring. While looking at it, clean it good.

[Allen Humphrey]

I think kcw is on the right path.

Engaging the safety pulls the striker away from the sear, thus allowing it to reset fully even if the rebound spring is weak.

[John Beard]

Hi good sirs,

I've noticed that occasionally, when feeding the first round of the magazine into the chamber, the trigger feels like it sticks at the beginning of the second stage. When the shooter goes to fire, there is no first stage pre travel, just a tiny bit of creep, then BANG. After manipulating the bolt to chamber the next round, the issue disappears and does not affect subsequent shots.

Additionally, cocking the striker and putting the safety on before opening the bolt and loading the magazine seems to prevent this, but it appears to be a potentially dangerous situation that needs to be remedied.

Thank you for any insight.

Chris

Based on your description, you have an extremely unusual problem and I have no diagnosis for it. But I concur that it's dangerous and needs to be rectified. The recommendations you have received for cleaning and inspection are prudent, but may not solve the problem.

I will mention that the bolt and bolt sleeve have some loose vertical motion which can affect the amount of sear engagement. Perhaps your bolt manipulation preceding your first shot is different from subsequent shots which can, thereby, inject variance in the amount of sear engagement and cause the problem to appear deceptive.

I recommend that you reload or acquire some dummy inert rounds and observe closely the sear engagement during and after bolt manipulation. You should be able to visibly capture the problem.

Hope this helps. Good Luck!

J.B.

[Darreld Walton]

One of the very first things to check, is to ensure that the trigger is not dragging on one side or the other of the aperture in the trigger loop. If it checks out there, then, take a look inside the stock to see if there isn't some crud, or perhaps a piece of busted stock banging around in the mortise in the stock. If those places are good to go, then put the magazine assembly on the bottom of the action, and run the screws in, and take a look at what's happening with it out of the stock, AND, use dummy rounds to duplicate the problem!

[ChrisATX]

Thanks everyone. Tomorrow's project is disassembly to examine. I will take photos and post here.

[ChrisATX]

I found no evidence of modification. All of the firing control parts are still covered in Greek black.

https://farm4.staticflickr.com/3797/13798359024_681bf1a70a_z.jpg
https://farm8.staticflickr.com/7015/13798354874_2cf0502fea_z.jpg
https://farm8.staticflickr.com/7079/13797997723_c1b84d9be9_z.jpg
https://farm8.staticflickr.com/7451/13798014023_4003c21f55_z.jpg
https://farm4.staticflickr.com/3720/13798340804_505c2fd865_z.jpg

[kcw]

The trigger "flops" around on its pin within the sear without resistance or getting stuck in one position? If the sear assembly is affixed to the barreled action without the sear spring, the assembly will move, unimpeded, in the normal fashion If the spring is then installed, the trigger will reposition itself from the "fired" position at all times as normally expected?.

[John Beard]

Chris,

Your trigger/sear assembly looks fine. But your receiver appears to have problems. The rough milling marks in the sear channel are very highly abnormal. I don't know if that's related to your problem, but it may be.

Hope this helps.

J.B.

[ChrisATX]

Hi John, thanks for taking a look. In person, these do not appear to be milling marks, but appear to be in the finish. They are also on the bolt. Where the trigger stages have taken the Greek black off in the sear channel, and where the action has worn away the greek black on the bolt shroud, the texturing doesn't exist, and it's glass smooth "in the white". Any where there is black on it, it is more textured than any other finish. Even the safety flag.

Here are some more pics:

https://farm3.staticflickr.com/2885/13809941565_142025577b_z.jpg
https://farm4.staticflickr.com/3778/13810277754_bbfe0abee3_c.jpg
https://farm3.staticflickr.com/2936/13809926453_98651664c5_z.jpg
https://farm8.staticflickr.com/7225/13810072593_37ca82523e_z.jpg
https://farm8.staticflickr.com/7252/13810039235_46fb4688e5_z.jpg

[ChrisATX]

More...

https://farm8.staticflickr.com/7391/13810104713_9c9b57e0f8_z.jpg
https://farm6.staticflickr.com/5010/13810164475_2d5abf1c17_z.jpg
https://farm8.staticflickr.com/7267/13810183703_3f34279f7f_z.jpg

[ChrisATX]

The trigger "flops" around on its pin within the sear without resistance or getting stuck in one position?

Both. It's almost like the sear pin is getting stuck.


If the sear assembly is affixed to the barreled action without the sear spring, the assembly will move, unimpeded, in the normal fashion

I will have to try this. Not sure.


If the spring is then installed, the trigger will reposition itself from the "fired" position at all times as normally expected?.

Correct, If the firing pin is not cocked, the trigger and sear assembly will not hang up. The spring always correctly returns the sear face up and cams the trigger forward to the stop as normally expected. The hang up ONLY occurs when the cocking piece face is on the sear face. After disassembly, it now hangs up nearly every time the bolt is cocked.

[ChrisATX]

Also, when cocked, if I use the safety to back the cocking piece off the sear, I get the trigger to return as normal without exception, even once the safety is returned to the fire position. Weak/worn sear spring and or friction on the sear/cocking piece interface? There is enough vertical play in the bolt assembly that if the sear face sticks as the bolt is being moved down and into battery, I imagine it could get stuck pushed partially down, as was mentioned earlier.

[John Beard]

Again, the milling marks are very highly abnormal. But that may not be related to your problem.

In examining the photos of your sear, I note what appears to be a tiny burr on the rear face of the sear. The rear face of the sear should have a glass-smooth, high-polish finish. If it has the slightest roughness or a burr, then that may very well be the source of your problem.

Hope this helps.

J.B.

[ChrisATX]

Huge help. Thanks so much John. I greatly appreciate it. Now I'm really curious about the milling marks now. :-/

[Punch the Clown]

Chris, two of my rifles had all kinds of trigger pull problems. The common denominator in both were the sear spring and the firing pin spring-they were very heavy. Replaced them both and the triggers are like butter. Both firing pin springs had unfinished ends-like they were cut from larger springs. Both sear springs were longer than any others I have. Don't know why but they're good now.

[ChrisATX]

The sear and cocking piece interface is indeed very gritty and easily shows resistance that could bind when examined together outside of the receiver.

The best recommendation for cleaning up and mirroring out these two faces without removing too much material?

[kcw]

The sear and cocking piece interface is indeed very gritty and easily shows resistance that could bind when examined together outside of the receiver.

The best recommendation for cleaning up and mirroring out these two faces without removing too much material?

Typically those two surfaces would be smoothed by the use of an appropriate stone. I can't tell you what an appropriate stone is, other than the one suggested to me at a gun show 25 years ago is darkish pink in color. The vendor had all kinds of stones and said that particular one was what was needed for "finish" work on gun sear surfaces. I've cleaned up a few dozen guns with it and it hardly looks used at all. A little spit is used for moisture. The final product surfaces shine like mirrors. Hopefully somebody else will be able to specify what specific type of stone you need for such work.

[John Beard]

The sear and cocking piece interface is indeed very gritty and easily shows resistance that could bind when examined together outside of the receiver.

The best recommendation for cleaning up and mirroring out these two faces without removing too much material?

You can try 600-grit sandpaper resting on a flat surface. That should be readily available from Home Depot or Lowe's.

J.B.

[Devil Dog]

It appears your rifle was completely refinished with the typical Greek "Blueing" which is not blueing but actually a coating. Most of these Greek "coating" are rougher than standard blueing. I think you problem is due to rough surfaces in all areas of the trigger.

[ChrisATX]

Thanks John. I did both with 600 since. Both faces are nice and polished... now the problem is most of the time I get a release before the second stage. Bear in mind I did not vertically shorten either surface. I imagine shortening the cocking piece face too far back would also make it hard or impossible for the safety lock to engage on the firing pin, so I was very gentle with it.

What is the correct height of the sear in the channel when the trigger isn't pulled at all, and then after the first stage?

[Parashooter]

http://i55.tinypic.com/8x3p5e.jpg

[ChrisATX]

Parashooter, I've been looking at that picture. Based on it, my first stage hump seems high.

Also to corroborate, if I watch the sear move in the receiver cocking piece channel, the vertical travel from taking up the first stage seems very excessive relative to how vertical play there is in the bolt while in battery (which translates to the variance of possible engagement amount there is between the sear the cocking piece faces before any travel is taken up). It seems like there is just too much vertical play in the bolt in this rifle. If I cock, then take the extra step to ensure the bolt is pushed all the way down, I get a to the second stage before release.

My understanding is that shortening the first hump may allow enough extra sear engagement to compensate for this vertical play.

[Jeff L]

I'm wondering if the trigger guard was bent somewhere along the way pushing the sear closer to the receiver than it should be.

[Parashooter]

. . . It seems like there is just too much vertical play in the bolt in this rifle. If I cock, then take the extra step to ensure the bolt is pushed all the way down, I get a to the second stage before release.

My understanding is that shortening the first hump may allow enough extra sear engagement to compensate for this vertical play.

Every M1903 I've owned or worked on has "too much vertical play in the bolt". However, if the geometry, finish, and lubrication of sear and cocking piece are correct, mainspring pressure nudges the loose bits into the same position each time the bolt is closed or safety released (assuming we then get our fingers off). This is how a well-tuned '03 has consistent let-off despite the designed-in clearances you've interpreted as "too much." With stock removed, observe the interaction of parts while operating bolt, trigger, and safety slowly enough to thoroughly understand what's going on there. With a little basic appreciation of mechanical principles like levers and cams, this should allow you to identify and correct any problem.

As stated in the illustration, "Reducing front hump raises sear and puts 2nd stage (when rear hump contacts receiver) earlier in stroke." Do you need additional clarification?

(The Norwegian M1912 Krag solves the vertical play problem with a little leaf spring in the raceway behind the sear, reducing the hand fit/finish time required to give a consistent pull.)

http://i43.tinypic.com/2qxrq5v.jpg

[ChrisATX]

Thanks Parashooter. I will look over things very carefully. Sorry for being thick skulled and slow on this.

[ChrisATX]

Some measurements:

Vertical sear engagement: 0.04"
Sear face height: 0.20"
Cocking piece face height: 0.15"

[ChrisATX]

I took Chuck in Denver's KISS advice. Replacements from Numrich.