New to using a 'F-CLASS BR' at 50 yards...

[OS OK]

Typically I test with ammo that has es's in the 30's. And yes I chronograph every shot. I look for setting that get the largest difference in velocity of those 2 shots and puts them in the same hole/next to each other.

Once you find where that tuner needs to be the setting will not change that much from lot to lot, velocity differences with ammo in the 1060fps to 1085fps.

"rounds are close or the same in speed...now we are looking at vertical stringing"
Nothing could be further from the truth!!!

The bbl's osculation will end at the same place (muzzle in same place/same angle) with identical or close velocities.

Let me see if I can translate my thoughts about this comment I made clearly so that you can explain a little more in detail how this is not accurate...I need to see clearly where I am thinking mistakenly and correct this in order to progress with this testing.
(I am referring to charts & graphs from Al's Varmint Page...[ http://www.varmintal.com/a22lr.htm ])

First, consider a 'fixed barrel' and the vertical distance between two shots @ 50 yds. ... with a 40 fps ES.



*_This is what we are basically asking the tuner to 'tune out'...or 'lessen', to 'make less spread in the POI'. Given these numbers, these two rounds are stacked side by side 'vertically'. Not much difference but it is a 'string'. All the other shots that are close or the same will fall in between this ES.
One of the problems with this number is that it comes from calculations using a fixed barrel that does not move...this is unobtainable in the real world.
Another problem is that each velocity within that ES generates more or less barrel vibrations, this in turn generates a different barrel angle when the round leaves the muzzle. The result of this will give us a little wider spread in the 50 yd. POI. That is vertical stringing and the amplitude is now variable but magnified over the theoretical 'fixed barrel'.

These numbers (from Al's page) so far are considering the barrel moving through space in an 'up/down' direction but...in the same direction.
In my mind I can see that distance of movement in a barrel quantified as 'X'.
*_We are going to ask the tuner to minimize 'X' by slowing down the average of all the barrel angles generated and to close this string somewhat. This is what we want.

On the other hand...my thinking is that by picking a set of 2 shot groups (several in a row with only the .001" barrel weight-increase) that clearly indicate that the barrel is changing direction in it's 'up/down' swing...then I think we cut the quantified 'X' by as much as 1/2.

This is what I think I can see in this string of 2-shot groups here..."imagine where the barrel was pointing when the round left the muzzle...then trace a line between them and they indicate that the movement of the barrel was primarily 'side to side' across the horizontal plane much more so than it's movement in the vertical plane."



I know wind & shooter have responsibility in the shot placement also but I have carefully chosen to shoot when the wind was shifting from it's 'cool night time' flow from the mountains behind me to the wind coming back in reverse from the valley below (the valley warms in the morning sun and heats up and that warmer air starts to move back up). During that hour or so in the morning the wind can be absolutely still yet can still move some & move in all directions as the change is happening...this morning it was no more that 1.3 mph (according to my now calibrated flags and the Caldwell meter I just received.)



I took my time to minimize the wind and my part of the distribution of these test shots. This I will do in further testing as I examine further what these 2-shot groups will look like in 5-shot multiple groupings. That's the best I can do to make this testing as accurate as possible.

If you examine the rest of the 2-shot groups on this first test of a .025" barrel-weight increase, I think you will agree that the barrel is pointing in direction(s) other than straight up and down as all the Computer Generated Numbers on Al's Varmint Page suggests.



I think we are seeing barrel movement(s) that suggest the barrel is actually moving in some circular fashion, I'm not saying 'symmetrically circular' but some kind of 'irregular looking oval'. I think that the torque of the barrel as the round is engraving & accelerating creates the horizontal component of the barrels total movement...
If true, this is pointing out that there is a horizontal component to consider when choosing a 2-shot group to further prove by 5-shots multiple groups.
This is why I chose what looks like the bottom side of that movement so that I could reduce the vertical component, hopefully....by as much as 1/2 -X.
Again...if true...that reduction will lessen to a greater extent the vertical & horizontal distribution of the ES when the tuner is tuned.

NOTE...This is the first .025" of adjustment of a total range of .500" and it is on the short end of the barrel 'weight-length' to start out.
I chose to start at the minimum because...as the barrel weight-length increases, it has less of an effect on total possible movement of the barrel.
The longer the barrel weight-length is...the more influence that weight will have on maximum variations of movement.

[Forrest r]

I'm not saying you're doing anything wrong. Everyone looks at things differently.

A tuner is there to take the vertical dispersion out of the ammo. A tuner has nothing to do with the horizontal dispersion. When you do see the tuner affecting the bullets horizontally, that's telling you to start taking a hard look at:
The easiest thing to correct, the torques on the hold down screws
Bedding issues
worst case scenario, mechanical failure due to action not being strong enough to support the bbl + tuner. Hold down screws are too soft. The receiver is being tweaked by the excessive weight of the bbl + tuner. Or simply a poor design with a ton of bbl whip.

Take that target above and measure how tall and wide (outside edge to edge) those groups are. Add the vertical #'s together and divide by 25 to get an average. Do the same thing with the horizontal #'s and get an average. With a 1.3mph wind you should be stacking the bullet high/low.

Looking at that target above it looks like 3 are a wash/too close to tell. 7 have vertical stringing. 15 have horizontal stringing

This is why I keep repeating bedding/action/torques. Take the horizontal stringing out of your targets in calm wind

[OS OK]

I'm not saying you're doing anything wrong. Everyone looks at things differently.

A tuner is there to take the vertical dispersion out of the ammo. A tuner has nothing to do with the horizontal dispersion. When you do see the tuner affecting the bullets horizontally, that's telling you to start taking a hard look at:
The easiest thing to correct, the torques on the hold down screws_Bedding issues
worst case scenario, mechanical failure due to action not being strong enough to support the bbl + tuner. Hold down screws are too soft. The receiver is being tweaked by the excessive weight of the bbl + tuner. Or simply a poor design with a ton of bbl whip.

Take that target above and measure how tall and wide (outside edge to edge) those groups are. Add the vertical #'s together and divide by 25 to get an average. Do the same thing with the horizontal #'s and get an average. With a 1.3mph wind you should be stacking the bullet high/low.

Looking at that target above it looks like 3 are a wash/too close to tell. 7 have vertical stringing. 15 have horizontal stringing

This is why I keep repeating bedding/action/torques. Take the horizontal stringing out of your targets in calm wind

Let me take your commentary an issue at a time before I say what I'm going to say about today's follies...

You said...The easiest thing to correct, the torques on the hold down screws___Bedding issues

I broke her open and carefully pried her apart (for the first time since I bought'er)...she is a very snug fit and definitely was bedded by someone who had been there done that before.



It has pillars front and rear for the action screws and those pillars extend completely through & flush with both sides of the stock. When the trigger mechanism dust plate and guard are removed you see how the pillars come in contact with those pieces and there is no wood of the stock sandwiched in between. When those screws are tight there is no slop and nothing in compression. I have no way of checking what the torque values were when I loosened them and don't know what the torque is now that I have replaced them...but...they are tight, not limp wristed tight and not overly tight...just tight. I do not understand the value of a specific torque setting when the fit is steel to steel all the way through the wood stock.

Next...(worst case scenario, mechanical failure due to action not being strong enough to support the bbl + tuner. Hold down screws are too soft. The receiver is being tweaked by the excessive weight of the bbl + tuner. Or simply a poor design with a ton of bbl whip.)
I don't know how to address this. This receiver and barrel are matched as perfectly as my eye could tell, all the way around, the receiver is center punched and that aligns with the index mark on the bottom side of the barrel...trying to get some flex between the two is impossible. I put the midpoint against the bench and pushed in several directions and I might as well have a solid piece of bar-stock in my hands...there's no indication of any failure of barrel fit, tightness of the threads or pins of any sort.
This is a receiver from a CZ452 Scout...having that receiver properly matched with a tapered bull barrel pretty much rules out excessive barrel whip and is standard procedure in the BR world as far as I know, I haven't read anything in all the articles about CZ's or books I've read that would suggest or indicate I have an unstable or miss-matched platform.

and finally...(A tuner is there to take the vertical dispersion out of the ammo. A tuner has nothing to do with the horizontal dispersion.)
I think this point is where we are in different camps. From all you have said, I take it that you believe the barrel does it's movement completely in the vertical plane, straight up and down and that's an end to that. Any horizontal in the groups has to be attributed to something outside of that movement...the wind, mechanical problems & bedding...I will throw in the ammunition's performance and me, of all the possibilities and their percentage to be at fault, I would most likely carry the heaviest weight...therefore, I can't explain all the measuring you suggest...just can't account for any of that in specific.
I did explain about the wind though, if you re-read what I said, the 1.3 mph was the highest recorded & it was not constant in velocity or direction. It was easy to shoot in between that condition and the calm I have at this time of morning. Today was the same except for the changing direction. The direction shifts around when you have a still air mass being pushed from one side by heat convection in the valley below...in a couple hours I'll have a steady breeze blowing up into the mountains behind where I live.

Where we are in different camps is that I believe that the barrel vibration...the whipping as you describe it is in the vertical & horizontal and by tracing the 2 shot groups one can see readily that the POA of the bore is not straight up and down but rather in some kind of oval at best. I believe that is primarily due to the torque of the projectile engraving & accelerating. Varmint Al goes on to describe a pressure bulge behind the projectile that he factors in with his computer simulations. That part hasn't registered with me as of yet since we have a bull barrel and the very low pressure a .22lr generates.

Anyway...enough with a Neophytes ramblings and imaginations...here's todays work as we look at Page 2's targets 11 ~ 15. I had intended to shoot 5 sets of 5 shot groupings for each tuner setting but at the last moment decided to shoot only 3 sets of 5 shots. That saved me a $15 box of ammo. If I choose one of these settings to work with in the future there will be plenty of 5 shot groups to follow & evaluate further.



There are some nice groups here in 0.0-13 & 0.0-14 although I did have a little quirk to occur.
At target 18, I had a miss-fire. I pulled it, actually had to walk to the shop and get a cleaning rod to push it out, then rotated it 180º and shoved it back in and shot it...I am not saying that made a difference in that grouping, I'm just saying that this occurred.
Also at that same time I noticed how sticky the previously cleaned chamber was getting from excessive paraffin lube. By the time I got to target 22, I decided to first clean the chamber again with a wet mop of Hoppes & dried it. I am not saying that had anything to do with the group on t-22, I'm just saying that this occurred.
I didn't go through the barrel with anything, I cleaned the chamber with a bent 17 caliber bore mop from the receiver side of the chamber.



If I had to choose one of these tuner settings today...I think I'd choose 0.0-13.
So . . . . this has been a look at the minimal side of the tuner's capabilities, I am thinking I should also take a look at the maximum side and at least compare the two.

[tazman]

Most of what you are talking about I can't comment about. I can talk about the screw torque.
When the screw torque changes, the stresses on the receiver change as well, making things flex and vibrate differently. At some torque setting or other, things will simply work better. Lots of articles and videos about how to find the settings that work the best for your rifle out there. I am not going to recommend any particular method or settings as I haven't properly tested my rifles yet.

In preparing for the range tomorrow, I cleaned the barrels of the two rifles I plan to shoot. I will be doing tests on a couple of different types of ammunition. I checked the torque settings on both rifles. I have a torque wrench similar to the large units that uses a rod separate from the handle to indicate the torque as the handle flexes slightly. Like this
It works in both directions so I can test the torque needed to loosen as well as tighten.
I checked the tightness first to see if things had loosened up since the last range outing by the simple method of tightening them further. Both rifles needed more torque to be applied to have the same torque I applied the last time I tightened them. They had loosened up slightly from sitting.
On the 455 the stock is just wood so I was expecting this. On the 457, there are pillars that the stock is bedded to. I wasn't expecting those to have changed but they did.
Both rifles are now cleaned and torqued appropriately and ready to go for the range session tomorrow.
The weather is supposed to be cool(55-62 degrees) but with little to no wind where I will be shooting. I am hoping for the best.

Before you ask, I bought my torque wrench off eBay and it cost about $20 shipped to my door. It is a quarter inch drive so it works fine with Torx bits.
It even fits into my shooting bag easily so I can take it to the range with me.

[OS OK]

Thanks Taz...I appreciate what you have said about the pillar bedded CZ. I am always open to suggestions but I also need a little explanation like you have given to understand. Who would have thought that pillar bedded screws would come loose if they are tight? What is your experience with various torque settings & how much can you see the various torques making a difference in grouping?

Some time ago I was looking into this issue and came across a video where a fella had a lot to say, was going to show the significance of torque settings on the action screws. He predicted what we would see as he changed them from low torques all the way up to his 'personal torque setting' that was suppose to be the bee's knees.
Everything he did somehow went south, nothing came out how he predicted and all his groups basically sucked like he was shooting some bulk ammo. I dropped the issue there & didn't look any farther. Guess that was my mistake.

Anyway, I have this inch-pounds torque wrench here, it is not at all handy especially with slotted screws...so I don't even bother with it.



I just looked into something a little more handy. I don't want to bugger any slotted screws...



If you think this might do the trick, I'll order it as soon as I hear from you or others with a favorable reply.

[303Guy]

OS, I've been wondering about the bedding on your rifle for a while. I would never have dreamed that the two screws would be positioned as they are. My thought was "there's the problem". In your case, torque is meaningless. What is required is pressure between the bedding faces and that you do not have. You have force on the steel pillars (I thought pillar bedding was something else).

Looking at that set up, what I would recommend is a piece of thin paper under the chamber. Start with cigarette paper or ladies pattern paper and repeat one of the two shot groups that are horizontally spread and see what happens. Try progressively thicker papers until the horizontal spread disappears or the exercise appears to be in the wrong direction. The wrap may need to be reduced so as to fit in the sides or one full half wrap plus a one third wrap or something like that. I suggest the very thin paper because the idea is to put pressure on the Knox form without actually 'stressing' the action. That is where screw torque has meaning.

Of course, I may be way off the mark but what I'm suggesting would be an easy process and would prove of dispel the bedding question.

P.S. That target #12 is very nice! Maybe there is no bedding issue after all. Still, there should not be any horizontal stringing which your multiple shot groups don't seem to have.

[OS OK]

OS, I've been wondering about the bedding on your rifle for a while. I would never have dreamed that the two screws would be positioned as they are. My thought was "there's the problem". In your case, torque is meaningless. What is required is pressure between the bedding faces and that you do not have. You have force on the steel pillars (I thought pillar bedding was something else).

Looking at that set up, what I would recommend is a piece of thin paper under the chamber. Start with cigarette paper or ladies pattern paper and repeat one of the two shot groups that are horizontally spread and see what happens. Try progressively thicker papers until the horizontal spread disappears or the exercise appears to be in the wrong direction. The wrap may need to be reduced so as to fit in the sides or one full half wrap plus a one third wrap or something like that. I suggest the very thin paper because the idea is to put pressure on the Knox form without actually 'stressing' the action. That is where screw torque has meaning.

Of course, I may be way off the mark but what I'm suggesting would be an easy process and would prove of dispel the bedding question.

P.S. That target #12 is very nice! Maybe there is no bedding issue after all. Still, there should not be any horizontal stringing which your multiple shot groups don't seem to have.

I am not sure I follow what your explaining.
The dark grey bedding epoxy matches the underside of the receiver, even the contours along the side that locks it into place, it is a glove fit & has to be carefully reassembled and pressed into the bedding because the alignment is so precise. If I understand what your saying about the chamber, that cutout area is for the magazine well. all around that opening the epoxy is in contact with every part of the receiver.
Maybe the picture is deceiving? Here's another picture with a little different angle...



As far as the horizontal in these groupings go I have already tried to explain what I think it is outside of a bedding problem or funky/loose barrel fit.
I have been trying to judge the performance of this CZ compared to the performance of a rifle action in a machine rest shooting the same Eley Match at 50 yards but in a tunnel. There is no wind, no loose action or barrel or operator error here...and I see the same basic irregular shapes of the groupings in respect to the horizontal displacement from a dead center one hole group.

[303Guy]

What I am trying to say is that the bedding fits the receiver and Knox form fully and evenly. But the forward action screw is about mid way and the rear screw is at the rear. Like you said, the two action screws are bottomed out on the pillars and therefore once tightened, do nothing to the pressure under the Knox form. In short, what you have there is a snug fit, not a pressure fit. So no amount or torque setting will make any difference. So, placing a thin sheet of paper under the Knox form will result in pressure being applied to the Knox form both on the sides and underneath.

As I said, I may be way off the mark but it's a simple test to do and will quickly show if there is any merit in it. One of three will happen; either it will get worse, nothing will change or it will improve.

[OS OK]

If I do that, it will create the same amount of space under the front of the receiver where the rifle barrel meets the receiver, the first 1.25" (aprox.) of the barel is bedded also.
If I follow correctly what you suggest, I think I will create a new problem, the front pillar screw will not bottom out steel to steel and have a space between it and the bottom of the pillar the same thickness of the compressed paper shimming, to tighten that up will try to flex the stock and bedding. The stock will flex long before the receiver will.
That's not making sense in my little pea-brain?

[303Guy]

Yup, you are following me correctly. However, it won't necessarily create a space but will create pressure on the Knox form which would hopefully stabilize it.

[OS OK]

After seeing this bedding job, you imagine it's not stable? How so?

[303Guy]

Because the bedding is an epoxy compound, it sets to the form of whatever is bedded in it and because the action bedding screws use the steel tube spacer system, if those screws are tight at the time the bedding compound sets, there will be a snug mating between the stock and the action but no pressure. All the pressure is on those steel tubes. If the two screws were located on either end of the action body, there would likely be no problem with that but because the front screw is located so far back, there is room for the action to flex within the bedding unless care was taken to ensure that there was pressure between the bedding and the action forward of the bedding screw.

So as it is now, (assuming that the bedding is 'neutral') the action is firmly clamped between the two screws but not forward of the front screw. There it is relying on bedding pressure. If on the other hand, there is pressure up under the Knox form, then the front screw torque will have an effect on that pressure.

So in the 'neutral' bedding scenario, as the system flexes during firing of a cartridge, pressure can develop from one side to the other or down onto the Knox form and relax again. That involves flexing of the steel and without the necessary pressure but being in contact, possibly irregular flexing.

But as I have said - I could be way off track. I've been wrong before. So I'm suggesting just giving it a try and see what happens.

You know, looking at the bedding portion of the stock, I see a possible fore-end resonance occurring and with the fore-end resting on something, possibly an irregular resonance. Pressure under the Knox form should fix that if indeed it is actually there. Again, I could be wrong.

If you were to hold the barrel in one hand and pull down on the fore-end with the other, I would expect the fore-end tp flex away from the Knox form.

Explaining myself has never been my strong point so please forgive my clumsiness.

[OS OK]

I don't know the brand name but they refer to this type bedding as 'steel bedding', they use it in the magnum calibers because it doesn't shrink and it is so resilient to flexing. I think using it in a .22lr is a kind of overkill. If that location of the forward pillar screw was a problem, I think I would have already discovered an article or video or two about what had to be done. I haven't seen anything about what you describe just yet. I suppose I could do some kind of search to see if this is a problem and it is out there.

Here's a question out of curiosity.
Take a look at the machine rest and the groups it shot with this Eley Match @ 50 yards in the tunnel. Notice how well that receiver is bolted to the rest and the barrel is literally clamped.
Notice the groups it has produced that have that horizontal displacement the same as I got today...ok?

Explain to me, if you will...why that machine rest is making the same horizontal spread.

PS...This barrel doesn't have a 'Knock's form'...it doesn't have a flat on the barrel, it is round where it screws into the front of the receiver.

[303Guy]

You have a good point there. Why horizontal and not vertical? This barrel harmonics thing is a whole nother rabbit hole! Mind you, most of those groups are little clusters. Where there is horizontal or other dispersion, it seems random. Well, I must concede that I am probably wrong.

[tazman]

OS OK----- I think the Wheeler might be a better fit for you if you have straight slots in your screws. My rifles have Torx heads so the driver I have works fine. The Wheeler would probably work for me as well.
I bought one similar to the Tekton but, with my poor hearing, I have trouble hearing the click. I sometimes end up over tightening the screws. Personal problem. The inicating sound on the Wheeler is supposed to be much louder.
If I need to torque straight slot screws, I will either get a Wheeler or replace the screws with Torx head screws.

303 guy-----Please explain what a Knox form is exactly for us poor under educated people. I don't remember ever hearing the term.

[barrabruce]

I think 303 is right in the regards to the bedding being neutral.
If the screws can’t compress the action down then it is just resting there.
If you torqued the screws to their elastic limit there would be only the compression of the aluminium tubing doing any thing.
I dunno if that’s a bad or a good thing.
You could try a bit of stiff paper in the back and front parts of the bedding.
Tighten down the centre bolt which will then flex the action and just nip up the back screw if you wanted to try flexing the action.

I think 303 is referring to the section of the barrell that tapers down to the thinner barrel section in front of the action with the spanner flat that SMLE rifles have
Known as a Knox form.

But those growed up around 303’s call the step from action end to where the barrel tapers down to a smaller diameter the Knox form as well. Carrying the term for that small section of barrel over.
First inch or so of the barrell sticking out of the action.

Must be a Ozzie /Nz / Canadian thing.

Hope that’s clear as mud.

[dverna]

Tazman,

I wonder if applying a bit of fingernail polish will "lock" the action screws so they do not lose torque setting. I suppose it is easy enough to just re-torque the screws every session...but do you think the torque changes during a session or just from sitting around after a couple of days?

We know that vibration will loosen a screw. Do the vibrations of repeated firings cause the same effect?

I like your idea to use a simple cheap torque wrench like you have. It would be interesting so see the "break away" torque needed to loosen the screws over time and how that changes.

Interesting stuff!!

[Forrest r]

OH boy

Not picking on anything buttttt:

That "front" hold down screw is actually the only hold down screw from the factory. The 452 cz scouts only came with 1 hold down screw located between the trigger and the mag.

A lot of people bought the cz scouts to use as donner rifles. But they were using them in sporter configurations. Actions with twisting forks (mag wells) tend to do better with lighter bbl's.

Who ever did the work put the rear hold down screw in. The $64 question is why am I seeing bedding over the top of the rear pillar in places???? If the action screw was tight and the pillar matched the shape of the action I should only be seeing the pillar.

303guy is correct, those action screws are doing nothing for you. They are too close together and too far back from where the receiver meets the bbl. The money shot is the hold down screw at the bbl/receiver junction.

As far as action screws go tazman's torax screw heads or the allen screw heads do a lot better then the strait slotted screw heads. Don't have to worry about keeping the torque wrench centered in the strait slot.

That bedding actually looks like jb weld to me put on in 3 separate stages, probably wrong but that's what it looks like.

I've posted this before and I'll post it again:
The easiest way to test for bedding issues is to put strips of rubber or compressed cardboard in the front of the stock as near to the front end of the stock as you can get. Put enough of whatever you're using to put upward pressure on the bbl.

I know you keep saying that bbl's go in a circular motion not strait up and down. My question is this:
Why is it then that shooters go out and test to get their bullet drops (vertical) and then get their "dope" for the wind (horizontal)????

[barrabruce]

Ghee better clean those threads well before you start.
And use some anti seize compound.
If you are serious about maintaining torque settings.
Wood will compress over time if the torque is greater than the woods ability to with hold it.
I found out that too.

I wonder if barrel tensioning using a long tube and nut kill barrel vibrations or at least make a node at the end of it?

[tazman]

Ghee better clean those threads well before you start.
And use some anti seize compound.
If you are serious about maintaining torque settings.
Wood will compress over time if the torque is greater than the woods ability to with hold it.
I found out that too.

I wonder if barrel tensioning using a long tube and nut kill barrel vibrations or at least make a node at the end of it?

That is what was happening in the 455 I own. Even though I was using recommended torque settings, the wood had slightly compressed and reduced the torque on the screws.

On the 457 with the pillars, I suspect just the vibrations from shooting and riding in the vehicle probably changed the settings over time. I am quite willing to check torque settings every trip to the range as needed.

OS OK----- I find the bedding on your rifle interesting. I have never owned a rifle that was bedded as tightly as yours.

I have centerfire rifles that are loosely bedded and do not have pillars that shoot better compared to MOA than these 22lr do. Why is that?
I haven't checked the torque on the screws on any of those, ever.