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Author Topic: Radical left curve while daily target shooting.  (Read 650 times))

Offline precisionaction

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Radical left curve while daily target shooting.
« on: December 01, 2021, 06:24:57 PM »
Let me apologize in advance if this topic is off topic.

Since getting my new MRod, I have been in a constant cycle of adding custom parts, tweaking setup, and zeroing. One thing that has proven to be problematic is after ever time I remove the scope with rings/mount, I always end up having to make large adjustments to windage to pull right or left. This time, I figured something is out of wack, having to adjust over 148 clicks / 37 MOA to the right. I have never had to do this before with any rifle. What could be going on?

Mrod is gen 2: 25 CAL.
Scope is UTG 4-16 x 54, 1/4 moa.
Rings are BKL dovetail high rise 30mm.
Target: 75 yards down range. Paper.
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Offline lizzie

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Re: Radical left curve while daily target shooting.
« Reply #1 on: December 02, 2021, 12:52:46 AM »
Thread moved to The Darkside...
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Offline anti-squirrel

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Re: Radical left curve while daily target shooting.
« Reply #2 on: December 02, 2021, 08:14:01 AM »
Let me apologize in advance if this topic is off topic.

Since getting my new MRod, I have been in a constant cycle of adding custom parts, tweaking setup, and zeroing. One thing that has proven to be problematic is after ever time I remove the scope with rings/mount, I always end up having to make large adjustments to windage to pull right or left. This time, I figured something is out of wack, having to adjust over 148 clicks / 37 MOA to the right. I have never had to do this before with any rifle. What could be going on?

Mrod is gen 2: 25 CAL.
Scope is UTG 4-16 x 54, 1/4 moa.
Rings are BKL dovetail high rise 30mm.
Target: 75 yards down range. Paper.
I'd start with a different scope and rings.
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Offline AlanMcD

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Re: Radical left curve while daily target shooting.
« Reply #3 on: December 02, 2021, 08:23:30 AM »
I would agree with Peter, but just to check - do your tweaks always involve removing and reinstalling the scope?  What are some of the tweaks that have led to needing the biggest adjustments? No tune adjustment should do that.

I would agree that what you describe is not normal, although with my M-Rods, they can require a bigger scope adjustment after a teardown than some of my "more robust" guns.  My Air Ranger is usually within just a few clicks, where the M-rods might need 10-15 absolute worst case . . . . any more than that and I know I did something wrong and will dissemble and reposition stuff and it gets better.
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Offline FuzzyGrub

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Re: Radical left curve while daily target shooting.
« Reply #4 on: December 02, 2021, 11:08:59 AM »
If the scope/rings are good, suspect the shroud or tightening may be pulling the barrel to one side.  Does the barrel look to be straight down the length of the air tube?  Has the shroud position moved, such that the barrel band needed re-centering? 
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Offline precisionaction

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Re: Radical left curve while daily target shooting.
« Reply #5 on: December 02, 2021, 11:51:49 AM »
Thread moved to The Darkside...

Thanks Lizzie! Sorry for the off-topicness...
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Offline precisionaction

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Re: Radical left curve while daily target shooting.
« Reply #6 on: December 02, 2021, 12:36:15 PM »
do your tweaks always involve removing and reinstalling the scope?

Right now, they have been. I have been testing a few prototype SSG's I have assembled, and tweaking the regulator. Yesterday, my third prototype of the SSG is functional, and my regulator is in better adjustment, although I would like to replace the stock hammer soon.

What are some of the tweaks that have led to needing the biggest adjustments?

By far, the adjustment yesterday was the most extreme at 148 clicks to the right. I had just installed my third prototype of the SSG, which entailed removing the scope, action w barrel, and tube end cap.

Does the barrel look to be straight down the length of the air tube?  Has the shroud position moved, such that the barrel band needed re-centering? 

In an effort to quiet the "ping" of the rifle, I installed two different sized rubber grommets inside the shroud between the barrel and shroud to act as a barrel dampener. This required me to shave off excess rubber from the larger grommets in order to allow them to fit under the shroud. Those larger grommets have been catching the shroud and sliding out of place during installation and removal of the shroud. Yesterday, while the rifle was disassembled, I took some sandpaper to those grommets to prevent interference with the shroud, and admittedly, this might have been the cause for the extreme change in drift. I had assumed, the extremely soft rubber of the grommet and the hard steel of the barrel would not cause interference, but actually provide a cushioning or even a stabilizing effect. I will take off the larger grommets and see if this makes a change in trajectory, the smaller grommets do not touch the shroud, so should not cause any issues.
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Offline Motorhead

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Re: Radical left curve while daily target shooting.
« Reply #7 on: December 02, 2021, 01:15:56 PM »
If your messing with Shroud, Baffles or added an additional LDC ???

CLIPPING most likely
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Offline FuzzyGrub

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Re: Radical left curve while daily target shooting.
« Reply #8 on: December 02, 2021, 01:16:38 PM »
I'd remove all the grommets and install the oem parts, at least for a test. 
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Offline kbstingwing

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Re: Radical left curve while daily target shooting.
« Reply #9 on: December 02, 2021, 10:30:19 PM »
make sure the barrel band is not pushing the barrel one way or the other, or like Motorhead stated, clipping, check the shroud end and the baffles for marks or damage.
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Offline precisionaction

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Re: Radical left curve while daily target shooting.
« Reply #10 on: December 03, 2021, 07:09:32 PM »
Everything has been removed, and right now, my shots are flying every where. I have not bedded the stock yet, seeing how the barrel rests on the air tube, but sure as all get out, it will be bedded by the end of the night.

Anyone have any ideas on what to do with the hole where the pressure gauge used to be? Moved mine to the tube end.
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Offline precisionaction

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Re: Radical left curve while daily target shooting.
« Reply #11 on: December 04, 2021, 02:18:23 PM »
CLIPPING most likely

It was not clipping, thankfully. There are no signs that clipping occurred, no damage to the baffles, nor the cap. The grommets were rounded and ground down as close to the inside diameter of the shroud as could be perceived. The grommet material consisted of a very soft and pliable rubber, that compressed out of the way when the shroud was installed. They have since been removed, reground into a thinner donut shape, and sit in the bottom of my shooting bag indefinitely. I used an expended co2 cartridge as a make shift mandrel, and a cordless drill as a lathe to ensure uniformity and roundness.

I'd remove all the grommets and install the oem parts, at least for a test. 

No OEM parts were removed, and all grommets lay inside the bottom of my shooting bag.

-----

The entire idea came from vibration dampeners used on tennis rackets, which make a big difference in the sound and pitch of some stiffer rackets. I am not sure if hollow tubes with the addition of a few baffles added to the end is the standard for airgun shrouds, but the theory was, there is little distinguishing this large empty space enclosed in steel from an echo chamber. Vibration and sound waves originating from the action, and/or from the movement of the projectile through the barrel, traveled through this hollow chamber and resonated off the steel walls encapsulating it. The purpose of baffles is to disrupt this resonating effect, which they do well, but they do not counter the vibration caused by the resonating effect, nor do they provide any barrier limiting the size of the chamber that resonates. If this hollow area could be replaced with a vibration dampening material and/or sound absorbing material, the effects of the resonation would be minimal.
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Offline FuzzyGrub

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Re: Radical left curve while daily target shooting.
« Reply #12 on: December 04, 2021, 07:18:04 PM »
How does it shoot with the shroud, baffles, and shroud spacer removed? 
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Offline kbstingwing

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Re: Radical left curve while daily target shooting.
« Reply #13 on: December 04, 2021, 08:59:04 PM »
What pellets are you using? is the Breech O-ring in place? is the barrel loose? what FPS is it shooting?
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Offline precisionaction

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Re: Radical left curve while daily target shooting.
« Reply #14 on: December 06, 2021, 05:16:48 PM »
How does it shoot with the shroud, baffles, and shroud spacer removed?

Loud, and my shots are way off the target once removed. Rifle is bedded, and shots are still spraying everywhere. Inspected all parts of shroud, and they show no signs of damage, and the shroud appears to be straight.
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Offline FuzzyGrub

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Re: Radical left curve while daily target shooting.
« Reply #15 on: December 06, 2021, 05:26:13 PM »
How does it shoot with the shroud, baffles, and shroud spacer removed?

Loud, and my shots are way off the target once removed. Rifle is bedded, and shots are still spraying everywhere. Inspected all parts of shroud, and they show no signs of damage, and the shroud appears to be straight.

With all the shroud removed and still spraying pellets, that grouped before, something else is amiss.  The barrel get damaged in the process? 
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Offline dan_house

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Re: Radical left curve while daily target shooting.
« Reply #16 on: December 06, 2021, 06:17:29 PM »
how far does the bedding go?

Way back when, I was advised to only bed the stock from the stock screw back and free float the rest of the air tube. Reason being is the tube can/will expand a bit and push the actionand barrel to other POI
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Offline umtys

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Re: Radical left curve while daily target shooting.
« Reply #17 on: December 07, 2021, 12:06:00 AM »
My Kral Maxi  suddenly started  spraying fliers to paper target in 20 yrds. , was accurate till then .Kral factory is not far away from the place l live so decided to make a visit. One of the workers making new rifles helped me sorting the problem with  directly changing the barrel after checking the leak and loose set screws etc  .It perfectly worked for me. Rifle was heavily used in last seven years and never had serious barrel cleaning other than few cleaning pellets l shot . Just my experience about a similar problem.
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Offline precisionaction

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Re: Radical left curve while daily target shooting.
« Reply #18 on: December 07, 2021, 02:39:27 AM »
The barrel get damaged in the process?

It didn't appear to be, the last time I checked, a few days ago. Since, it arrived, the rifle has been a mediocre performer. I do not know whether this is due to inexperience with PCP's and tuning with the correct pressure or what? I fill the tube up to around 200bar, which is quickly depleted, so I usually have a secondary tank connected and filled to a little less than 200bar as well.

how far does the bedding go?

All the way. I am typically stingy with my application of epoxy. This causes me to layer another application or two on top to fill the gaps/air pockets, but this time I mixed a substantial amount to also fill the hole where the pressure gauge used to go, and to avoid a secondary layer. I still have a gap or two to fill, but all in all, it is a nice application.

The tube was pressurized at around 150 bar during bedding.

-----------------------------------------

I will check out all the shroud and barrel again. This time using a square to check for any deformation.

----------------------------------------

I have been disappointed with the factory length of the barrel, and felt that more performance could be squeezed out of the platform with a longer barrel. So far, this does not appear to be a common mod to the rifle, and I have only found one place that offers upgrades for it.

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Offline precisionaction

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Re: Radical left curve while daily target shooting.
« Reply #19 on: December 07, 2021, 05:33:43 PM »
Now I am more than 17.52 MOA to the right. I am going to take photos of everything.
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