Accuracy Report
For some reason my POI changes in steps as I use up air in the tank. I can understand the pellet dropping but it goes from left to right at the same time. Take a look and try to explain.
Talon SS with 18″ barrel, 100 gr.hammer, stock spring, polished hi-flow valve, JBS 18’s and a 2700 psi fill and a 900 psi end.
The point of aim was the bull but I have it zeroed at 45 yds and I shot at 10 meters indoor using my bipod on a table.
The middle circle is 1″ so it does not look so bad here, but at 50 yds it”s a 4″ spread.
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How did the gun shoot before you put on that large cocking arm on your breech?
I wonder if the mass and moment arm of that cocking arm is causing a stress to the tophat and barrel when shot?
Maybe you should take it off and see if it is making a difference.
I kind of thought it was the barrel myself, my other barrels do not do this. Just to try it I turned the barrel 90 degrees, I just moved the bottom bushing holes to the side and just used 2 grub screws.
Point of impact did change, of course, but after 20 shots they still moved left and down, no change.
I’m going to try my 24″ barrel again and see if it is my hammer spring setup.
Like a number of people said, I can pick a fill zone and get a decent 25 shot string and live with that.
I have tried different pellet and weight, same result. What I do find interesting is that it repeats itself over and over again. So I think the gun itself is very consistent, could be just the way this barrel works.
This might sound crazy, but here is what I would try assuming nothing else has helped.
Rotate your barrel in the bushings about 60°. It is quite possible your bore is not straight, and the highest pressures are forcing it straighter in the opposite direction it is bent.
Walt in Hi. mentioned this very principle in a thread about barrels, I cannot remember which thread.
At any rate, if its the barrel you will notice the same trend but in a different direction if you rotate it. If this is the case, you might have to live with it, but you could index it so the POI change works in your favor.
R.C., i meant the excercise as a demonstration of the frames inherent lack of rigidity, not as a field expedient. 😆 it was merely suggested as a way of demonstrating frame flex. i also concur, that hammer is way too heavy. especially for the velocities shown. as far as the maddog stocks being ugly, that’s a personal preference. i kinda like them, myself.
Adam,
Could be, but I suspect this fellow probably understands that. He states that his groups are wandering at 50 yards in a 4 inch spread.
I can’t really understand why someone would want to shoot one at 33 feet, it is not what I would consider a 10 meter gun.
I feel sort of cheating shooting mine at 36 yards, but then that is just me.
The other day I did a eye opening parallax exercise. It was foggy out and I wanted to see what my scope on cast slug gun did as far as paralax when used with the laser.
Activating the laser, I could see the trail it cut thru the fog from the muzzle out to 50 yards easily, looking thru my scope, and doing the side to side and up and down movement to check for parallax was interesting in that it would cross back and forth on that laser beam in the fog, out to a certain point where it was parallx free and did not move acrossed the laser beam.
It was interesting seeing it being parallax free and not parallax free all at the same time.
Being a take down rifle brings its own problems to the table, I have quite a few time where my bottle seemed tight, but when checking it after firing wide groups, a minute bit of play was evident.
Regards,
Roachcreek
I have not noticed it with my AA S410 or my Royale. They do not seem to shift POI like the AF rilfes do.
Which is one of the main things I like about those rifles, in addition to the ergonomics.
RC
First off lets not forget the AF rifles are “Take Down guns”. So you must beware of limitations and work around them.
Also if you push pellets fast enough you will get POI change in any air gun.
The key to fixing a problem is finding the problem. People run around doing a lot of things to their gun hoping they are working on the problem when they do not know if it is actually part of the problem.
Shooting a gun sighted in at 45 yds at 10 meters away is going to be a problem just in the fact the scopes do not excell in focus or parallax correction at 33 feet.
Long Hunter,
May I sugest using a stock hammer instead of clamping it to a 2×4 and then a table.
With the lighter hammer he will notice a superior degree of portability over the 2×4 and attached table while in the field. 😛
Of the Wok guard and the RL stock choice, I have both on Air Force rifles. The RL solution will be the best for combating frame flex, but to me it is simply butt ugly, no punn intended and while the Wok guard does not entirely do away with the frame flex as efficiently as the RL stock, it is indeed more pleasing to the eye.
Regards,
Roachcreek
OK, my 2c. you’re using a heavy hammer. you’re NOT using a WOK guard. your frame is flexing, it would seem, less and less as your pressure drops, causing your poi to shiift. try this, take the forearm off, strap the gun to a 2×4, TIGHT, clamp the 2×4 to a solid table and brace the underside of the trigger guard. make sure everything is nice and level. then shoot a group. you’ll see what i mean. it will probably shoot a one hole group, or damned close to it. if that is the case, you have several options. get a WOK guard, or get an R&L stock from Tony. either way, your shooting will improve.
Adam,
I have not noticed it with my AA S410 or my Royale. They do not seem to shift POI like the AF rilfes do.
Which is one of the main things I like about those rifles, in addition to the ergonomics.
RC
We do.
Talk to LD and he will tell you all you want to know about this.
The middle circle is 1″ so it does not look so bad here, but at 50 yds it”s a 4″ spread.
Parallax my friend.
You have it zeroed at 45 yards (135 feet) and are shooting at 10 meters(32.8′)?
Look through your scope at 10 meters without touching your gun.
Move your head up and down, side to side. Does the cross hair move?
Shooting at 10m is very close and scopes have a hard time at that distance eliminating parallax.
Try this. Shoot your gun at 45 yards with parallax adjusted for that distance on 4x or 6x and you might just watch your groups get tighter.
One of the first things you can try when shooting a gun for accuracy is to decrease magnification down to 3x or 4x and shoot the gun. You will be surprise how all of a sudden accuracy improves.
Try it and let us know what happened
If these theories about speed and expansion of the pellet are true, why do we not see this with other air guns, AA S410/510, FX, and Daystate?
They all deal with pellet expansion and diminishing velocity.
It could be a combination of engineering events that produce a perfect engineering storm: a flexible frame, the valve dynamics, the breech design, hammer impact and poorly secured bushings that create a design flaw, that is partially midigated by a superb barrel.
Regards,
Roachcreek
Maybe pellet skirt expansion, due to more air flow.
maybe the precession of the pellet is affected by varying velocities?
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looks pretty normal to me , i have never had a bullet just drop straight down with a variation in velocity like that, you have over 300 fps in 90 shots…powder or air. get the variable fps down and you get your impact variation down.
bet ya a shiny nickel that a reg condor will not vary like that for a shot string that stays on the reg for a nice SD.
here is some reading
http://en.wikipedia.org/wiki/Magnus_effect