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Alstone · Moderator & Site Supporter

Just lately I’ve been having trouble with zeroing for windage and I’m not sure what the problem is, although I think it is me.

The weather is quite good at the moment so I took the opportunity to go down the field and do some long distance shooting with my TX200; I set up targets for 15 and 25m to start with. After zeroing in at 15m and firing a few test shots, which were ok, I moved on to the 25m target adjusted the elevation but left the windage where it was set, after shooting a few rounds they were all going to the right of the bull, so I adjusted the windage and brought the shots back on target, everything was now ok and getting good groupings, anyway I moved back on to the 15m target and the shots were landing to the left of the bull. To my way of thinking once the windage is set I shouldn’t need adjusting only for the wind and on this day there wasn't any.

The scope is level and lines up with the gun ok, I even strapped a laser on to it and it lines up perfectly. So to test things out I drew some lines on to a piece of card and set it up at 15m, then shot a test round with the TX with the scope set at 9x, good shot right on the cross, I then got my QB78 out of the car loaded it up and using the red dot fitted, shot off a few rounds which fell to the right of the vertical line, which didn’t matter as this was only a test to see if the pellets hit the same spot at 25m. Moving on to 25m the shots from both guns fell to the right of the poi, so I must be the problem not the guns.

So what could the problem be I have tried changing the way I hold the gun, adjusted the trigger, these tests were all done with a bench rest and a leather bag filled with sand as support, I’ve tried with and without a silencer fitted, changed the scope mounts and changed my glasses but to no avail. It happens with different guns so I can only think that I am doing something wrong, but what?

Al

Rogerflat · Silver Status Member

Yep. At least now I don't feel as bad for my shooting troubles. It's so dumb too. You tune your rifle in to be spot on, then set it down. When you pick it up again it is way off. It is probably something in the scope that does it. Frankly, it is really starting to annoy me though.

My philosophy is that you may be "pulling" the POI to one direction or another, but as long as your pull is consistent, then you should be able to account for it. I sight in by resting my rifle on the window sill, so it is far from secure, but my shooting is so consistent that I can get tight groups by doing that.

I get into trouble when I change distances, angles, and have to set the gun down overnight.

My theory is that Robert Gulay sneaks into my room late at night and turns the dials on my scope. That is the best explanation I can come up with.

Alstone · Moderator & Site Supporter

Once set for say 20m it stays there no change whatsoever, it's only when you increase or decrease the poi that problems accrue, which if you want to do a bit of FT mucks things up a bit.

Al

23ib0d0n · Moderator

Are you using a scope level in your tests to eliminate cant issues? 5° cant would produce about 10mm variance from point of aim at 25m with a 16 ft/lb gun IIRC in .177, although gravitational effects vary with velocity and ballistic efficiency.

http://www.arld1.com/images/swfs/targetplottrajectory3.swf

Other than cant, it would seem to be 'walking out' with the trigger pull.

Alstone · Moderator & Site Supporter

Hi J
I do not have a scope level but I did check the level of the target box, and line up the cross hairs with it.
I'll print out the test target and give it a try tomorrow, also J what is Thumbing as that looks like a possibility.

Al

Rogerflat · Silver Status Member

It's possible that you are doing so much thumbing that the cant of the scope is causing some walking out and scope creep.

That may not actually mean anything, but sometimes its fun just to use scope jargon.

23ib0d0n · Moderator

"Thumbing" refers to excess or inconsistant pressure applied by the thumb. Kind of a 'white knuckle ride' concentration. Using video to critique the trigger pull process can help alot with hold issues.

If you set up targets at several different distances, are results progressive? If results are progressive, then cant is more likely a suspect.

Hold problems are often very similar looking, even when targets are nearer, which is why cant was the first thing I thought of. That, and you outshoot the majority in competitions.

Use of any simple level to allow consistant hold between the bore of the rifle in relation to the line of sight to show if it is a cant induced error. I've used carpet tape and a small picture frame block level on occasion to check the amount of angle I induced when seating the buttpad into my shoulder crease.

If you had more problems with actually hitting targets, then hold problems could be more plausible Rolling Eyes

broommaster2000 · Moderator

Trigger-finger?

Mar · Veteran Member

Maybe something like this link shows is happening.

http://www.arld1.com/nutation.html

Alstone · Moderator & Site Supporter

J, I went down to the range this morning to try and sort the thing out, first I borrowed a clamp on level set everything up and things did improve, the variation between 15 and 25m was 15mm, now it’s down to 6mm, which is an improvement, no problem with “thumbing it” as I tend to hold the TX fairly loosely. One thing the guy who owns the range did notice was the way I hold the forestock, this is the result of breaking my left arm when I was 5 years old and it not being set correctly, this means I am not able to get my hand fully round the forestock properly especially with the thickness of the TX, with only my finger tips getting round to the right hand side, this according to the range owner puts a bias to the right when shooting and the more kick the worse it gets, I did try and screw my hand further round the stock and things improved quite a bit but it is difficult to repeat this way of holding the gun for each shot.

So for now I will have to alter the windage for different rangers when target shooting, as when zeroed up for a particular range my shots remain constant. Also with field target shooting most of the targets have a 20 to 40mm hit point so with a 6mm variation I should be able to hit anything between 15 and 25m without needing to adjust the windage, or should I say the gun can hit the target whether I can is another story

Al

Update
Went back to the range after lunch and was talking to a guy who is well into Field Target, and he was saying that some people using springers especially Air Arms TXs and Weihrauch, have been dropping the power to about 10.5 flb which gives them less kickback a smoother gun and better accuracy, if this is complemented with a lighter pellet you can keep the same velocity.

As my TX output as been creeping up towards 12flb and is in danger of going “hot”, It only takes a few minutes to remove a power adjustment washer so I striped it down and removed a couple of washers, put it back together and gave it a try with a crony, the output had dropped to 10.3 flb, also the problem I had to start with had all but disappeared, and the accuracy as improved.

So all in all a good days work.

Al

23ib0d0n · Moderator

Glad to hear it improved.

As for the forestock 'hold' try this and see if it is helpful for you; I also have problems with my forearm due to torn muscles and tendons, so I don't 'hold' the the forestock at all.

I open up my hand and rest the stock on the palm pads while lettings the fingers relax. This method of just supporting the forestock usually works pretty well for me shooting springers and it is the offhand style I used to win the hunter FT at AAF in Lavon, Tx a few years back.

How I support the rifle . . . offhand hitting the 100m bunny.

The win . . . me in the long sleeves.

AirGunEric · Site Admin

Good job there Al- glad you got it sorted out.

J.- has anyone ever actually seen your face? Razz

In respect to the holding technique as well- you could try the match hold the "experts" advise people to use (typically on very low powered springers, other relatively recoil-free guns like Co2 and PCP) where you use the top of your hand to merely support/hold up the forearm of the gun. Personally, I can't shoot like this at all, I find it uncomfortable and irritating. Of course, I also don't seem to shoot worth a darn these days- so my opinion on the issue is of little consequence.

Alstone · Moderator & Site Supporter

Hi Eric
The problem is I cannot hold my left hand palm upwards, the nearest I can get to that is 90 degrees so I have to hold a gun in the V between my thumb and first finger which works quite well until you need to grip the stock, which on any airgun but a Springer would be no problem.

Anyway reducing the output to 10.5flb seem to have done the trick, and I needed to reduce it because it was getting very close to the limit, you never know when your gun could be checked by the police that it is under 12flb.

With the weather improving at the moment I have used my co2 rifles this weekend for the first time, and compared with a Springer they are very easy to shoot but you do not get the same satisfaction.

Al