How Can I Fix Vertical Stringing?

Improving and repairing firearms. Rifle bedding, barrel work, stock replacement and other ways to improve your firearms.

Re: How Can I Fix Vertical Stringing?

Post by Gwion » 04 May 2016, 12:44 pm

Over lubed firing pin causing hydraulic resistance and inconsistent striking?
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Re: How Can I Fix Vertical Stringing?

Post by Wm.Traynor » 04 May 2016, 1:54 pm

Gwion wrote:Over lubed firing pin causing hydraulic resistance and inconsistent striking?


AHA!
I noticed an hour ago while cleaning the barrel, that the gease that I smeared on the locking bolt, could have entered the hole for the firing pin striker. Grease had definitely come in contact with the striker itself. Note; not to be confused with the firing pin in the bolt. I hosed the striker with G96, on noticing the build-up around its hole and the striker freed quickly.

Good call Gwion :D
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Re: How Can I Fix Vertical Stringing?

Post by Gwion » 04 May 2016, 2:16 pm

Interested to see if it fixes the problem. Only thought of it because a friends rifle had FTF recently and that ended up being the problem. He had never cleaned out the heavy grease from the factory and LIGHTLY lubed it with oil.

Hopefully it fixes the FTF and see what happens with the stringing.
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Re: How Can I Fix Vertical Stringing?

Post by Rocker » 06 May 2016, 3:40 pm

Gwion wrote:Over lubed firing pin causing hydraulic resistance and inconsistent striking?


That would result in vertical stringing only? Not horizontal/random too?

*head scratch*
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Re: How Can I Fix Vertical Stringing?

Post by Chronos » 06 May 2016, 6:06 pm

Rocker wrote:
Gwion wrote:Over lubed firing pin causing hydraulic resistance and inconsistent striking?


That would result in vertical stringing only? Not horizontal/random too?

*head scratch*


I think the theory is it may cause inconsistent ignition giving a range of velocity readings and therefore elevation changes but I doubt you'd see anything at short ranges.

I reckon the elevation issue is directly related to poor action bedding

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Re: How Can I Fix Vertical Stringing?

Post by Gwion » 06 May 2016, 8:36 pm

Chronos wrote:
Rocker wrote:
Gwion wrote:Over lubed firing pin causing hydraulic resistance and inconsistent striking?


That would result in vertical stringing only? Not horizontal/random too?

*head scratch*


I think the theory is it may cause inconsistent ignition giving a range of velocity readings and therefore elevation changes but I doubt you'd see anything at short ranges.

I reckon the elevation issue is directly related to poor action bedding

Chronos


I tend to agree. The greasy firing pin was just a suggestion re: failure to fire.
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Re: How Can I Fix Vertical Stringing?

Post by Rocker » 06 May 2016, 9:14 pm

Makes sense, didn't think of it like that.
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Re: How Can I Fix Vertical Stringing?

Post by Wm.Traynor » 09 May 2016, 4:55 pm

Had another crack at it today with 14 test loads. Only one FTF, about #3 I think. Went off after re-cocking the hammer, as usual. That's better than 1 in 4.

Fired 3 shot groups for each load. All groups strung out vertically but in the last two groups, there were a pair of shots an inch apart with the third 4 or 5" away. Hardly an improvement.
Only the rear band was "tightened", for today's experiment. Now I will have to work on the front. It will be even more difficult and I was hoping to avoid it but there is no getting round it.

BTW, maximum loads were extracted with ease. I've just gotta get this gun to group. It's too good to give up on :)
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Re: How Can I Fix Vertical Stringing?

Post by Gwion » 10 May 2016, 3:30 am

Double grouping, from what i understand, tends to indicate the barreled action is hanging up in the bedding and does not have free battery. The stringing can be upward pressure on the barrel.

I'd give the whole striker system another strip and clean, then lightly oil it; if it has improved but not perfect, there may still be a little crud left in there. If you still get FTF, i'd look at a new striker spring, at the same time look for wear on the striker end of the firing pin indicating that it is being interfered with mechanically, preventing a consistent strike.
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Re: How Can I Fix Vertical Stringing?

Post by Wm.Traynor » 10 May 2016, 9:24 am

Thanks Gwion. I will have a close look at All that :)
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Re: How Can I Fix Vertical Stringing?

Post by Gwion » 10 May 2016, 9:31 am

No worries, mate. Like i said, i know nothing about lever action rifles and this is all from my rudimentary knowledge of how bolt actions work re: accuracy faults. Hopefully some of it translates but i can't give you any further details.
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Re: How Can I Fix Vertical Stringing?

Post by Wm.Traynor » 03 Dec 2016, 11:44 am

Well, here I am again with the promised update. Had to postpone work on the Mossy for a longer term project. The failure to fire was fixed with a no-name, spare spring from a gutted old rifle that my 'smith had lying round. Very handy of them. Worked like a charm :D Thank you Pine Rivers.

I continued to address the vertical stringing methodically, so I thought, by reducing the contact between barrel and fore end. carefully, wood was gouged out and the finish smoothed with coarse abrasive on a socket. Even more carefully, the barrel channel was widened just a little, so as not to leave too ugly a gap. Mongrel came with me to Belmont where we did a Lot of shooting. My results weren't too bad. Groups were a bit smaller, so I figured that in "going looser", I was on the right track.

The following weeks were spent on other things :D to the neglect of shooting stuff but recalling past results, I checked the fore end and found a bit more work to do. Memory is hazy on this work but groups were from 2 to 3" and I wanted better. I kept recalling that in the really bad, strung-out groups, the windage was only 1". Rightly or wrongly, I was encouraged and motivated by that thought and the fore end was removed once again to loosen the fit in the front of the action. Remember, I was trying to be methodical; doing one change at a time so as to isolate the cause of the stringing but there was a catch. The rear barrel band screw was bent again. This was the replacement screw that had been sent Free. Then I recalled that loosening the Original screw was the cause of bending in the first place. Too much time had elapsed since the project had begun for my memory to cope with even this important detail. Asking for another one was Unthinkable so I did something else that was also Unthinkable and straightened it. Too bad if it broke. I had nothing to lose and it worked.

But now, there was a problem. Going loose was not the solution. Still believing that barrel vibration was bending the screw, I tried to think of what to do. I rejected the idea of a rubber screw :twisted: 8-) but later thought of installing an O-ring, to more or less dampen vibration. I was a bit hazy on detail but in almost no time, a ring had been trimmed and inserted between fore end and barrel.

Results at the range yesterday with some "working-up" loads for a new bullet, were Disappointing. The vertical stringing had returned. Loosening the rear barrel band screw in stages was ineffective but the loads weren't too hot as we progressed through incremental increases in charges. Another rifle was tested while the Mossy cooled, after every 3 shots. I wasn't taking any chances at spoiling this experiment by over heating the barrel. The front barrel band screw was tried after re tightening the rear but to no effect and 3 live rounds of maximum charges were left. The front screw was re tightened and the magazine cap screw was loosened one turn. The following group was 2.5" wide, 1/2" deep and close to the middle of the target. The vertical dispersion had disappeared :o :D The rifle was put aside while testing continued on the second rifle, a rimfire, for 20 shots. It came to me suddenly that I had brought the remainder of the original ammo with me. Perhaps there had been the vague idea of testing it too but after changing to a fresh target, I turned the screw in, one half turn. What did I have to lose? I actually hoped that the horizontal spread would shrink a little, even if it increased the elevation. The next two shots were dead level horizontally, right at the very top of the target. Carefully, I inspected the backing board in the area above the group making a mental note of the holes that were present, so as not to confuse them with my next shot. But it was not to be. The RO called a ceasefire :shock: Hmmm. Patiently. I waited while a target change ensued and the third shot, when it happened, formed a group, 1/4" deep by 1.75" wide. Oh Happy Day. :D That is two bullet weights and no vertical stringing. That can't be a fluke, can it?

But here's a thought. That final screw, the magazine cap screw, makes no contact with the barrel. As pointed out Very Early in this topic, the is a blind hole in the underside of the barrel to accommodate the nose of the screw but it makes No contact with the bottom or sides of the cavity. I had forgotten that too. Had I recalled it, I would not have touched it. This gets back to postponing work on projects, only to resume long after the results have been forgotten. So does anyone know why the last screw worked?
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Re: How Can I Fix Vertical Stringing?

Post by Wm.Traynor » 18 Nov 2018, 8:26 pm

2018-11-18 15.00.25.jpg
A better view of the crack?
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2018-11-18 14.59.01.jpg
The Least Of My Problems
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Wm. TRAYNOR EATS HUMBLE PIE

It is my melancholy duty to inform the forum, that the O-ring fix was no fix at all. During testing at Imbil yesterday, the dreaded stringing reappeared. Examination of the rifle revealed that the mag tube was protruding past the muzzle :crazy: Stripping the rifle revealed a crack in the fore-end :wtf:

You can just see the dried beads of glue.

Hmmm. Not sure if these pics posted in the right order but anyway that was an easy fix. However, the main problem remains. While things were apart it was apparent that the mag tube and barrel are in contact; I think. Much more work to do. In the meantime, don't buy one of these @#$%^ things.
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Re: How Can I Fix Vertical Stringing?

Post by Wm.Traynor » 19 Nov 2018, 7:24 pm

2018-11-19 15.54.07.jpg
For some reason I fitted the mag tube to the barrel. No idea why. This shows how it fits at the muzzle-end.
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The tube has been gently pulled as far forward as possible
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Re: How Can I Fix Vertical Stringing?

Post by Wm.Traynor » 19 Nov 2018, 7:43 pm

2018-11-19 15.57.10.jpg
The tube has been moved all the way back. The blind hole in the barrel is for the turned-down section to fit into. Plainly. the tube is free to move, playing havoc with the elevation, I think.
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2018-11-19 16.12.47.jpg
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Re: How Can I Fix Vertical Stringing?

Post by Wm.Traynor » 19 Nov 2018, 8:43 pm

2018-11-19 16.27.33.jpg
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[attachment=0] That is the tip of a screwdriver between barrel and tube. There is quite a bit of clearance between screw and barrel, never mind the screw's hole. No wonder the tube was able to slide forward.
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Re: How Can I Fix Vertical Stringing?

Post by Wm.Traynor » 19 Nov 2018, 8:50 pm

2018-11-19 16.31.45.jpg
2018-11-19 16.31.45.jpg (1.05 MiB) Viewed 188 times
Yes, this O-ring clamps barrel and mag tube in place but I'm not really serious. There must be a better way to stabilise the tube and reduce stringing.
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Re: How Can I Fix Vertical Stringing?

Post by Wm.Traynor » 19 Nov 2018, 8:57 pm

2018-11-19 16.42.07.jpg
2018-11-19 16.42.07.jpg (1.17 MiB) Viewed 188 times
This is the underside of the barrel, showing the blind hole that the screw is supposed to fit into. You can just make out, at the muzzle end of the hole, a shiny bright area. There is some slight deformation of the perimeter of the hole here, which leads me to believe that the screw has been colliding with the barrel, on its way out of the hole during firing.
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