How Can I Fix Vertical Stringing?

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How Can I Fix Vertical Stringing?

Post by Wm.Traynor » 24 Apr 2016, 9:31 am

My Mossberg 464 strings vertically. The front and rear barrel bands are loose and you can move them easily with your fingers. There seems to be no pressure between the screw for the magazine cap and the barrel. A hole has been drilled in the underside of the barrel to accept this screw which fits easily without bottoming-out; the bluing at the tip of the screw is intact and the mag tube is loose enough to be pulled away from the barrel.

The rear barrel band screw is bent and that is all that I can find that is wrong with this rifle. The screw is difficult to remove and install and I am worried the turning the screw might be damaging the thread in the band. However, the fore end will move back and forth a little. The screw was not tight enough to prevent movement. I have heard/read, where such looseness is not a bad thing but this rifle shoots 6" vertical goups at 50 yards that are little more than 1" wide.

How can I shrink the vertical down to the horizontal spread? That would be very nice :D

As an experiment (another one :( ) I am going to test some loads with the fore end removed. Last Thursday I shot gripping the fore end instead of resting it in the cradle of the front rest. I pulled the rifle in to my shoulder, resting the back of my hand on the cradle. The butt-end rested on the rear bag as usual. If it groups without the fore end next week, as I suspect it will, that will tell me that there is something wrong in front of the action. But what will it be? The bent screw?

I am sorely tempted to try to straighten the screw but that could work harden it, couldn't it? And that could lead it to break. Is that right? I will try to order a new one from the US. Maybe Brownells. It should be faster than an Oz dealer and by the time I travel to and from the shop, the petrol gets very expensive :o Cheaper overall to get something posted from the States I think.

Well, what are your opinions? Is it the screw? Is everything too loose? I welcome your wisdom. I don't have a clue :? :?
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Re: How Can I Fix Vertical Stringing?

Post by Chronos » 24 Apr 2016, 10:25 am

Oh boy, what a pickle. Hahaha

Firstly if the connection between the shooter and the barrelled action isn't consistent then you've got an issue. You need to sort out the stock as a priority. Even if you try and straighten the bent screw it may never be right. Just take it to an industrial screw and bolt place and get one the same.

Some smart placement of business cards could tighten everything else up then go shoot it again and see what happens.

All that plastic and metal can be hard to tighten up, once I got it sorted I'd even consider epoxying everything together tight

Good luck with it and keep us informed.

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Re: How Can I Fix Vertical Stringing?

Post by Wm.Traynor » 24 Apr 2016, 11:22 am

Thanks Chronos. So firstly, you think everything is too loose. Second, would such a screw be available "off the shelf". I always thought American gun screws had no resemblance to anything of ours. But there you are. Learn something everyday :thumbsup: I have a list of metric and imperial threads and will compare it against the chart.
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Re: How Can I Fix Vertical Stringing?

Post by Chronos » 24 Apr 2016, 12:43 pm

TBH I don't know if anything is too loose but mate i'd be trying everything before i wasted any more ammo

what cal is it?

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Re: How Can I Fix Vertical Stringing?

Post by Wm.Traynor » 24 Apr 2016, 4:45 pm

Chronos
It's a 30/30, the only lever centrefire that Mossberg makes

bentaz
Matching will not be straightforward. The diameter is 0.111" and as near as I can calculate, there are 38 teeth per inch.
I think importing will be the way to go but I will have a look at metric threads first.
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Re: How Can I Fix Vertical Stringing?

Post by sbd3927 » 24 Apr 2016, 10:30 pm

Trying to envisage what the bands might be, and how they are loose, some matches with old rifles I've seen.

Before trying to chase down a matching thread for an authentic repair... why not try some hose clips? Use some packing card, plastic, inner tube if marking the finish is a concern, or even tighten them over the existing bands. Lock it all up tight and see if it's the start of a solution.
Ie. if matching the thread in the band is the problem, make a new band? Depends on skills available.. or a gunsmith.
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Re: How Can I Fix Vertical Stringing?

Post by Gwion » 25 Apr 2016, 6:18 am

For screws and such, Brownells sell a huge colection of screws online. There is even a 'complete set' of gun specific screws that you can buy in an organiser at quite a reasonable price. You might want to stock up on other things to make the postage worthwhile, though.
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Re: How Can I Fix Vertical Stringing?

Post by Wm.Traynor » 25 Apr 2016, 10:06 am

sbd3927
If you entered www.mossberg.com and looked for their lever guns, you would soon see what the barrel bands looked like but you are right, I am looking for some packing to go between the bands and the barrel and bycycle inner tube could be a place to start.
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Re: How Can I Fix Vertical Stringing?

Post by Wm.Traynor » 25 Apr 2016, 10:07 am

Gwion
I will be looking up Brownells, thanks.
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Re: How Can I Fix Vertical Stringing?

Post by Wm.Traynor » 26 Apr 2016, 10:54 am

Hey you blokes, guess what.

Glen Bontoft of Phoenix Sports Trading, is sending me a screw in the mail today, FREE.

What a Good Bloke :D :thumbsup: :clap:

Neither Brownells nor Numrich, even list the 464 :o
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Re: How Can I Fix Vertical Stringing?

Post by Gwion » 26 Apr 2016, 11:25 am

Good news! :)
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Re: How Can I Fix Vertical Stringing?

Post by Rakk » 26 Apr 2016, 2:17 pm

Top notch. Great service :thumbsup:
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Re: How Can I Fix Vertical Stringing?

Post by Wm.Traynor » 03 May 2016, 4:03 pm

As threatened in my initial post, the rifle was tested without mag tube and fore end. It still shoots vertical groups and is failing to fire one shot in four after a change of primers. The previous brand FTF too but all the factory ammo worked a couple of weeks ago.
Over the weekend a 0.010 brass "shim" was epoxied inside the rear barrel band to take up the space between the barrel and band. It fits very snugly :) The new screw came while I was at the range this pm and it screws in easier than the bent one. Thank you Phoenix Sports Trading :thumbsup:

I have been wondering if the looseness of the rear band might have resulted in or contributed to, the screw becoming bent. For instance, could the vibration of the barrel during firing have hammered a bend in the screw, or was it installed bent originally?
These lever guns are one helluva learning curve :crazy: :huh: :wtf:
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Re: How Can I Fix Vertical Stringing?

Post by Gwion » 03 May 2016, 8:45 pm

Wm.Traynor wrote:My Mossberg 464 strings vertically. The front and rear barrel bands are loose and you can move them easily with your fingers.



Sounds like a crappy problem to solve. How the hell do you bed everything nice a solid on a rifle like this? I have no idea but good luck with it all!
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Re: How Can I Fix Vertical Stringing?

Post by Bazooker » 04 May 2016, 8:29 am

I read somewhere recently that vertical stringing is associated with variations in neck tension/crimping?

Trying to think of where that was.

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Re: How Can I Fix Vertical Stringing?

Post by Bazooker » 04 May 2016, 10:08 am

Here is an article that could contain some clues:-

http://www.6mmbr.com/verticaltips.html

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Re: How Can I Fix Vertical Stringing?

Post by Wm.Traynor » 04 May 2016, 10:15 am

Bazooker wrote:Here is an article that could contain some clues:-

http://www.6mmbr.com/verticaltips.html
Baz.


That was interesting mate. I am getting FT fire issues and thought that they were separate problems but maybe that and the stringing is connected.
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Re: How Can I Fix Vertical Stringing?

Post by Bazooker » 04 May 2016, 11:11 am

Dragging firing pin? need to check it for straightness, also check firing pin hole for off centre?

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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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