D460, Bend Barrel?

[nced]

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.................

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.............

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............

[Mark 611]

excellent post ED!!!!!!

[Artie]

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.

[Jr007]

I have a Parrus .22 and RWS 460 .22 tune by John PA if anyone looking for one its in the Stockton Craigslist.

[HectorMedina]

Artie,

I'm glad I was able to explain myself.

Good luck and keep us posted!



HM

[Artie]

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?

[Artie]

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.

[HectorMedina]

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/ 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

[Artie]

Thank you Hector for the explanation and advise. Good luck over there!

[WHITEFANG]

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.👍