GTA
Airguns by Make and Model => Diana Airguns => Topic started by: Artie on August 16, 2018, 08:12:32 PM
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I recently purchased an individual's unused .22 T6 D460 and finally got around to some paper punching today. The gun is tuned at 700+ fps with RWS SD (16+ fpe). I set up a poster board to determine the first rounds initial area of impact. Beside it was a separate zero/test target, both set at thirty yards. I used a centered ao scope setup for testing that is mounted to 11mm dovetail rings.
First round revealed the need for a dropper mount and windage was significantly right of center mass. Two more shots confirmed the group was 7 1/2" low and 6" right of the aiming point. I chose to swap out scopes/mounts. I selected an optically centred side focus and a UTG DN 10" drooper mount. I tested again..
With a .040 elevation shim I'm printing groups within clicks of vertical zero and windage of course, still impacts @ 5+ inches to the right of aiming point.
Should I acknowledge this amount of deflection and accept it as a constant source of annoyance or should I bend the barrel? I've done it to a cheap break barrel but this isn't that.
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Several posters have discussed bending of barrels on many different guns over the years. Personally, I've never done it and I used Sportsmatch windage and elevation adjustable mounts on my 460 with no shift of zero ever detected. More than one way to go.
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ya why not? why would u not try to bend the barrel? if you think u have it optically centered and it shoots like that why would u not try to fix that? Diana's are mint to shoot with iron sights so scoping will change things, so If you need to make further adjustments for scope usage then do so!!!! ::) :P
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Put a straight edge along the barrel to check it horizontally and vertically to see if it perhaps really IS bent. It is also possible the dovetail grooves are not cut into the barrel correctly. If the barrel is bent you may wish to consider bending it back to straight.
If it was my gun and the barrel was not bent I would probably go the compensating mount route.
Do ensure you have installed the scope mount correctly. Many mounts have a reversible side so they will work in either 3/8" or 11 mm dovetail grooves. Be sure the correct edge is the one you are using on your dovetail. When putting the mount on your gun also be sure the stop screw is aligned with the stop hole and not preventing the mount from settling properly into the grooves. The mount can be clamped tightly even if incorrectly seated.
I know - this sounds like idiot stuff but it is really easy to overlook these things. (Don't ask.)
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I did verify the stops were properly positioned and the mount tightened square to the rail with no cant. No doubt the barrel is down and out.
I have experience with a Diana adjustable mount from years before and it refused to hold zero. That's my experience with adjustable mounts. Windage adjustable rings concern me too. In either case, mount or rings, extreme care must be exercised to ensure both rings are correctedly aligned with relation to each other. Otherwise excessive stress could be applied to the scope tube while torquing the ring caps. I would like to hear more about a good adjustable ring set if someone has more insight/experience on the subject.
I am not keen about bending the barrel either, I've never done an under lever, but may be willing to tackle it. Hopefully someone with hands on experience will chime in.
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Scope stress is a valid concern. The locking mechanism on the Sportsmatch rings seems to be designed to avoid such stresses through the nature of the locking mechanism. I've heard others say they have used the FX mounts successfully as well but I'm not sure they are windage adjustable as I've never used them. Alternatively, one could bend away.
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I estimate scope centerline to bore is @ 2.25" and I'd like to lower that too. Bending is tempting because I could then minimize the centerline distance while raising the impact point. Both in combination would lessen the amount of vertical adjustment I'm thinking.
I also figure If I'm going to bend the barrel in one axis I may as well take care of the other while doing it. If it were a correctable elevation only situation I'd be content to call it a day the easy way. Not the situation unfortunately..
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I have had good luck with the BKL Droop mount on all of my Diana's, but your 460 sounds like it may be way out of whack? As much as I disliked the adjustable mounts, I think I too would go that route but would consider trying to do a return on the Rifle before I tried bending the barrel, but that's just me.
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The droop I can eliminate with the UTG compensation mount or RWS lockdown that I also have on hand. The windage error combined with the elevation error kind of nudges me toward curing the problem rather than patching it if that makes any sense?
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As Mark Stated = Why Not?
Bending the barrel is no biggie, I have had several occasions where it was required. I.E. D48 shot 14 inches low at 25 yards = bend that baby!
Got it to a couple of inches of being on target and then used the turrets.
Happy Shootin!
Petey
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Have you adjusted the scope any or is it still centered. With the reticle centered at 30 yards 7 1/2 and 6 inches is not out that much. You don't need to bend the barrel just adjust and zero the scope. Unless I'm missing something else you said.
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I’ve never seen a (bent) barrel it’s always in the breech lockup on a break break
Barrel’ if the droop mount doesn’t correct things it needs to go back’ I don’t bent barrels’
Maybe the rules sometimes’ 😂’
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I'm aware RWS has a reputation for droop. I'm also taking into consideration the gun is a .22, is detuned to 16 fpe and the target is thirty yards away. Gravity takes its toll and I'm not surprised the pellet drops. There is still droop however and RWS provides a mount that compensates for most of it. A .040" shim under the rear mount and 10 clicks down I'm good on elevation.
Windage requires 103 clicks left to correct for windage. That's a lot of adjustment in my book and I've become somewhat finicky about having the optics centered with the bore as much as possible without significant reticle adjustment. I know a lot of the competition guys have few qualms about tweaking barrels.
It was a fairly tedious effort aligning the barrel on the Gamo I fooled around with. Lots of trial and error, lots of disassembly, guesswork, testing and do-over to get it where I was happy. A great deal of care was required to protect the finish and not disfigure the gun although the Gamo wasn't worth fretting over frankly. It was and still is my guinea pig for experimentation.
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Droop as mentioned is common on all Diana guns be it BB or lever. Another factor that is possible is the bore is not true centered. Many guns are not a true straight bore vs the OD of the barrel.
If you have checked the barrel only and not referenced the barrel off the block area and the barrel shows no bend then take a framing square or machinest level and indicate off the top and side of the block.
You may get a different indication from side to side? I have seen this many times. As long as the barrel is straight on one side but not the other you still may be ok.
On rebarreling a Diana 48/460, if the gun had droop prior to installing the new barrel the new barrel will still have droop. It's all in the drilling of the block.
On all my past Diana guns the best scope mount has been the factor dropper or the UTG drooper weaver to dovetail.
Barrel benting on a lever gun is more difficult than a BB.
Just take care in your bending attempt. You want the bending to be as mentioned at the block or barrel attachment point. No rainbowing. That's a 15mm barrel which will make bending a bit easier. I have jigs made to work barrels that really work good. Go slow and remember the barrel will flex back so all measurements need to be after the pressure is removed. You weakest area is the loading area of the receiver. You do not want to bend that area. If that area get damaged you are screwed.
Returning the gun is your best bet. 103 clicks IMO IS MUCH. .JMO
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Whitefang, by "two different measurements from side to side" do you mean the x & y axis?
As far as elevation... I'm willing to live with the droop. My yard allows me to range targets from 0-50 meters, maybe 60 meters if I wanted. I may want to revert to full power at some point and that would raise the poi so I may not want to exactly dial the gun in at the current 30 yards we are discussing. The UTG compensation mount due to the picatinny design allows for some adjustment because the ring spacing can be opened up or closed a little, changing the angle.
So for me It really comes down to the windage error. It is "much" as you say.
The gun was unused. I am however, the second owner, having purchased it second hand. It is not a refurb nor do I have the original packaging or paperwork. I'm thinking returning to Umarex is not an option.
As suggested, I will do my best to measure barrel deflection from the block to discern the actual fault. I will also measure scope rail parallelism.
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Left side vs right side. Yes with the weaver rings you may be able to shim the attachment with thin shims for windage. But in doing so you will have to shim the solid side of the ring. Meaning you will have to install the rings so to move the scope the correct direction.
You could laser the bore for an indication. Incert a bore sighter and aim the gun vised at a wall. Either use a magnetic laser as on some levels and see where you are at. Even a string will work. This will at least give you another reference point of the bore vs the OD of the barrel. Many ways to check all of this. We know the farther out you shoot the more the gun is going to shift poi if the barrel is off. Sane as the droop if not compensated for.
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Artie;
Did you get the original box? Was it in perfect condition? Can you be sure that no one seated on the gun by mistake? I've seen and corrected lateral bends that happened when someone laid the gun on the couch and someone sat on it. I have also seen rifles that got mistreated and showed strong lateral deviations.
460's are USUALLY, very straight. It is just the way they are made.
In the 460's the "droop" is USUALLY, only the result of geometry, in break barrels, there are two or three other factors that come into play, but in the 460, it is USUALLY, only geometry (LOS height, vs distance to the target).
Whether in FP (24 ft-lbs) or tuned to 16 ft-lbs, if you REGULATE the barrel (proper terminology for "bending the barrel") to be on POA with good, aligned and trued mounts with a good quality scope at 35 yards, the 50 to 75 yards zero will only change by less than ¼ turret turn. So, do not worry about the future power level of the gun.
The process I follow is simple:
Get a zip tie, tie it tightly to the muzzle and straighten the tail of the zip tie.
Shoot a group at 10 yards.
Turn the zip tie so that it points to the group's position
Use some soft clamps in a STRONG VISE and place the gun's barrel, in such a way as to have the barrel block as close as possible to the vise's grips.
Turn the gun so that the zip-tie tail points directly AWAY from you.
Tighten the vise and then PULL the gun straight at you. Try to "register" how much force you are exerting.
Put the action back into the stock and shoot another group.
Note how much the group has moved and relate that to the force used.
Repeat till you get groups to shoot about 1½" below POA.
Now move the target to 35 yards and fine tune the regulation.
This is a photo of the target of a recently regulated gun, a Walther LGV that has some peculiar characteristics (16 ft-lbs 0.177", 3X fixed mag Xbow scope, as close to the barrel as possible):
(https://imagizer.imageshack.com/v2/572x763q90/923/Y6q6Hs.jpg)
See how the process goes, slowly, and measuredly.
Go slow and you cannot go wrong.
The last three shot group is the 35 yards one, and there was no regulation done between the 3rd shot and the group.
From the three shot group, the POI was moved using the turrets.
Black aiming mark is a little under ½"POI at the bottom of the ½"mark tells me it will be dead on at around 21 yards and the first zero should be at around 16 yards. Customer's choice.
Hope this helps you muster the courage to do it yourself.
If not, then DO send it to a professional. You do NOT have to live with adjustable "thingies", shims, or other type of jerry-rigging.
Keep well and shoot straight!
HM
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Fascinating and elegantly simple Hector. The gun is in impeccable condition though it came without the original box. I would have preferred the box over the nice case it came with.
Before I venture further I took the advise of a few of the previous posters and did some measuring. The rear of the scope rail centers on the safety's red dot and the front centers on the "Magnum" imprinted on the receiver. Therefore I believe the rail is parallel to the compression tube.
I used a 48" straight edge that I tested against my lathe bed for trueness and did my best to measure windage deflection with the action mounted. I measured the barrel from the block to the front sight mount (12"). I laid the straightedge on the stock's left side top edge (beartrap release interferes on the right). I measured several times and came up with 1.5mm (3/64th") right deflection each time. That small amount surprised me quite frankly though the straightedge is in reality only a very good ruler therfore I can't speak for the true integrity of the measurement. I can say my eyeballs do not detect any deflection and why I measured several times. Maybe bore?
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Look in the GTA library for do it yourself barrel bending rigs or the CDT web sight there is a wealth of info on the best ways to do the barrel bending you also may want to consider removing the cocking lever from the action before starting the process. don't forget make small corrections and test fire after each adjustment especially since you need to correct windage and elevation both
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I did a little calculating and a windage deflection between 3/64" and 1/16" puts the projected impact in the neighborhood of my current uncorrected group (not accounting for droop). Yard sticking barrel drop isn't nearly as easy with the gun as windage is but a little backwards math and an estimated 5/64" droop plugged into the calculator puts the impact @ 7" below the target which is where the pellet is actually impacting.
I conclude not much of a corrective bend is required to solve my problem and that removes much of the intimidation I have.
I have researched barrel bending in the forum Tom and used much of what I learned to practise on a Gamo cheapie sometime back. Hector's method is new to me however and the simplicity of the effort is enough to convince me to try it.
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I recently purchased an individual's unused .22 T6 D460 and finally got around to some paper punching today. The gun is tuned at 700+ fps with RWS SD (16+ fpe). I set up a poster board to determine the first rounds initial area of impact. Beside it was a separate zero/test target, both set at thirty yards. I used a centered ao scope setup for testing that is mounted to 11mm dovetail rings.
First round revealed the need for a dropper mount and windage was significantly right of center mass. Two more shots confirmed the group was 7 1/2" low and 6" right of the aiming point. I chose to swap out scopes/mounts. I selected an optically centred side focus and a UTG DN 10" drooper mount. I tested again..
With a .040 elevation shim I'm printing groups within clicks of vertical zero and windage of course, still impacts @ 5+ inches to the right of aiming point.
Should I acknowledge this amount of deflection and accept it as a constant source of annoyance or should I bend the barrel? I've done it to a cheap break barrel but this isn't that.
For years I've bent the barrels of my HW springers to align the "point of impact" at 30 yards with the "point of aim" using an optically centered scope. The optical centering is done using the "mirror method" if I find that the reticle centering of the scope "straight from the box" is within a couple clicks from centered on the reticle reflection in the mirror. If the reticle centering in the mirror isn't close then I use a "spin the scope in Vees" method. Since I found that my 30 yard zero is very close to my "upstairs 18 yard zero" I do my "barrel bending" till the poi at 18 yards is about 1/8" lower than the aim point using a home made "barrel bender" like this.................
(https://i.imgur.com/kP9eWigl.jpg)(https://i.imgur.com/rsK0loXl.jpg)(https://i.imgur.com/nppgPMCl.jpg)(https://i.imgur.com/9M6gXwNl.jpg)(https://i.imgur.com/mfVQ9Q4l.jpg)(https://i.imgur.com/a3A9W5al.jpg)
My "barrel tweaker" puts all bending on the barrel itself which isolates the bending pressure from the joint where the barrel is pressed/screwed (depending on the age of the R9) into the barrel pivot block. Also, adding enough bend to move the poi 4" at only 18 yards can't even be seen with the naked eye. LOL...the "4 inch bend at 18 yards" was due to trying to use a RWS "droop compensated" Lock Down mount with a Beeman R9 that didn't have "typical RWS barrel droop".
Here is an example of some minor "barrel tweaking" of a new "bought on sale" .177 HW95 barrel after installation.............
(https://i.imgur.com/yXJd6eCl.jpg)
Surprisingly, after the "new barrel bore clean" the "1st group" poi settled in considerably closer to the aim point (the numbers above the bull) than I expected at 18 yards, however the poi was still to the right of the aim point. Matter of fact, I think that any further zeroing could have been done with the scope turrets, however normally a change of barrel, scope, scope mounts, etc needs more "barrel tweaking". Anywhoo.....since "barrel tweaking is a rather easy procedure using a "barrel tweaker" I bent the barrel a tad to the left and shot the 2nd group anyway. The poi which was OK "windage wise" but a bit too low (about 1/2" low) so a second barrel bend "added a bit of snoop". Then the poi was "good enough" for me and all fine adjustments were done at my back yard practice lane at 30 yards (my normal zero).
My only purpose for "barrel tweaking" is to get the point of impact at 30 yards within about 1" of the point of aim to keep the scope erector assembly close to centered inside the scope tube. This maintains good "erector spring pressure". keeping the erector assembly from "thrashing around" due to the two way piston gun recoil............
(https://i.imgur.com/J2CpYnHl.png)(https://i.imgur.com/u95ysdwl.jpg)
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excellent post ED!!!!!! ;) :P
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I'm familiar with your post Ed and have saved it to my favorites. I didn't want to get into the scope centering discussion too deep because of the controversy it seems to stir up at times. I will say from my experience the bathroom mirror optical method is usually close to factory optical and mechanical zero. It is also fast whereas the V-block method can be tedious. One thing about counting clicks for mechanical zero, best to use a collimator or mirror for that too to ensure the clicks actually move the reticle. Especially with cheap scopes. Ask me how I know.. "dead" clicks at the end of adjustment where the only thing moving is the turret and finger tips. Sometimes lots of dead clicks.
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I have a Parrus .22 and RWS 460 .22 tune by John PA if anyone looking for one its in the Stockton Craigslist.
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Artie,
I'm glad I was able to explain myself.
Good luck and keep us posted!
HM
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Perfect explanation Hector, thank you. If I capisci anyone can.
I have decided to tweak the barrel after reviewing everything I'd done. I must amend an earlier statement I made regarding mechanical & optical zero (mirror method). The two methods may be close, as I stated, or not so much as I determined this morning. That begs the question of which method to choose.
The scope I will be using is a side focus and unlike an AO scope, the objective bell position remains static as I place it against the mirror. I select minimum ocular (zoom) power and infinity for side focus because it offers the clearest image. Relative positions of the reticle and image to each other change very little as the power or side focus is varied. The scope holds zero and is repeatable.
Now a question for the wise:
On this scope my windage mirror optical image and mechanical zero are virtually the same, less than 10 clicks difference. The elevation OTOH, deviates 68 clicks. The mechanical elevation must be raised 68 clicks to lay the reticle on top of its image and theoretically achieve optical zero.
Do I choose one method over the other, split the difference and adjust to that, or quit sweating the small stuff and get to bending?
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Trust but verify.
I measured the barrel several times with a straight edge in relation to the compression tube after removing the front/rear open sights. I measured 3/64" right deflection, 3/64" droop in 12". I then measured a leveled compression tube in relation to the barrel with a machinist level, @ 7/10" bubble fall to muzzle from barrel block.
I then used a sight-in collimator to verify a comparative sight picture of the two centered scopes I was using, the 30mm 3-12 side focus I used in my previous tests and a new 1" Vortex Diamondback AO that I hadn't tested yet. That was after both scopes reticle's were mirror centered then finely adjusted with a vee block to produce a tiny concentric circle around an established 30 yard aiming point. Both scopes were tested on a UTG MNT-DNT06 dropper mount, the same mount I had been using.
I went to this trouble because I wasn't convinced the droop & R deflection was nearly as bad as my previous tests indicated. All my measuring was prooving otherwise and I was right.
The target below shows a five shot, 30 yard group with Crosman premiers and no adjustments. The other pictures show the collimator and sight picture of the two scope's reticle zero-points. Disregard the scale (1=4") on the collimator sight picture, I'm using the grid as a reference point only and not for 100 yard powder burner zeroing as designed.
The side focus scope still impacts 5" low and right.
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Perfect explanation Hector, thank you. If I capisci anyone can.
I have decided to tweak the barrel after reviewing everything I'd done. I must amend an earlier statement I made regarding mechanical & optical zero (mirror method). The two methods may be close, as I stated, or not so much as I determined this morning. That begs the question of which method to choose.
The scope I will be using is a side focus and unlike an AO scope, the objective bell position remains static as I place it against the mirror. I select minimum ocular (zoom) power and infinity for side focus because it offers the clearest image. Relative positions of the reticle and image to each other change very little as the power or side focus is varied. The scope holds zero and is repeatable.
Now a question for the wise:
On this scope my windage mirror optical image and mechanical zero are virtually the same, less than 10 clicks difference. The elevation OTOH, deviates 68 clicks. The mechanical elevation must be raised 68 clicks to lay the reticle on top of its image and theoretically achieve optical zero.
Do I choose one method over the other, split the difference and adjust to that, or quit sweating the small stuff and get to bending?
Dear Artie;
I'm in Poland now, so this will be a brief answer because I have to go check my zero and establish my trajectory at the old quarry where the http://wftc2018.com/ (http://wftc2018.com/) are going to be shot between Thursday and Saturday.
If BOTH your AO scopes (and I have every reason to trust the Vortex Optics AO one in particular) say that the barrel is not that far off, as the results of your 30 yards test group shows, then the problem is your SF scope.
Change it.
Explain to the retailer or person that sold it to you, or even the manufacturer if that is needed, the tests you have run and that the scope's mechanical axis is OFF in relation to its optical axis, and that you cannot control the optical axis, just mount to the mechanical axis.
If they do not change the scope, then you write here the brand and complain, because no scope should have that much deviation between mechanical and optical axes.
Glad you performed all these tests, they point out clearly what is the problem.
Keep well and shoot straight!
HM
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Thank you Hector for the explanation and advise. Good luck over there!
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Very good sharing on the barrel dialing in and expaining. Hate it when the end result throws a scope into the mix but thing happen.
It takes allot of work checking out issues sometimes and it also takes some brain work.
Much knowledge has been thrown out in this post.
Glad you worked this issue out.👍