What am I doing wrong?

[melter942]

I have the Gamo Urban 22 mounted with a Hawke Vantage IR 4-12 x 50 scope. 
My back yard range has the shooting bench inside my tool shed with target stands built at 15, 25, and 50 yards.

The gun is a great shooter, but every time I take it out back for some shooting fun, I have to start the shooting session with re-zeroing the scope. A couple days ago, I posted pics of some sub-1/2" groups shot at 25 yards. Today, I went back out, set up and loaded with the pellets this gun likes best, and it was hitting 1/2" low and 2" left. Once dialed back in, it sent everything I fed it into nice tight groups.

In my last thread, someone had mentioned removing the barrel band. I don't fully understand the concept, but I need to try something. I bought this gun for varmint control (chipmunks and squirrels) and most of that activity will be shot from the second floor of the house into the back yard. My fear however, it that by the time I take the gun back to the house and stand it next to the window, it will have already lost zero.

Here's a pic of today's fun, but it began with sighting-in the FX 15.89s shown in the center of the target sheet.

 

[nitrowoodtic]

Yes remove or cut the barrel band

.

It,s much easier to just cut the top part for the barrel band off. Leave the bottom part so the fill port cover fits properly.

Then move your forward scope mount as far forward as your scope will allow.

 

[biohazardman]

A few more suggestions for troubleshooting your problem.

Clean the barrel and shoot a few shoots after you do before you expect your accuracy to return.

Try a different scope

Remove the silencer

Check for leaks at the breech

Also check for burrs at the crown or the chamber

 

[Odoyle]

Don't rest or lean the barrel on anything.

Check to be sure the barrel is tightly securely mounted and won't twist nor pull out or in.Try testing if the barrel moves deliberately pull hard push hard and twist it.

Wedge a piece of PA Pellet tin packing foam between the stock and wall you lean it against if leaning the gun so the barrel doesnt touch anything.

You also want to tighten all the scope ring screws top to bottom and if it still does the POI zero problem the next time you shoot after all this and stop leaning the barrel against anything then time to change your scope.

 

[Willie14228]

Don't rest or lean the barrel on anything.

Check to be sure the barrel is tightly securely mounted and won't twist nor pull out or in.Try testing if the barrel moves deliberately pull hard push hard and twist it.

Wedge a piece of PA Pellet tin packing foam between the stock and wall you lean it against if leaning the gun so the barrel doesnt touch anything.

You also want to tighten all the scope ring screws top to bottom and if it still does the POI zero problem the next time you shoot after all this and stop leaning the barrel against anything then time to change your scope.

Yep I found out about this one with the Marauder, I would stand it up at the back door come back and my zero will be different drove me nuts

 

[L.Leon]

Just loosen the barrel band screw, you don’t need to cut the band off. 

 

[nitrowoodtic]

Easy to test.

Zero the rifle. Push the barrel to the left or right, and release. Shoot a group.

 

[thammer]

I'd start with remounting the scope and ensuring everything is tight. If that isn't a fix try a different scope before cutting a barrel band. You could remove it and see but there are 100 topics of adding barrel bands for the same issue you're having. 

 

[Ripper]

I learned a while back not to lean my shrouded barrel gun against a corner or a wall. They always changed POI Every time. Now that I stop doing that, no more problems.But I’m sure that it’s more of a problem for certain guns.Like others have said, check your scope mounts also but I would say leaning the gun against something is your main problem.

 

[boscoebrea]

I have a couple of PCP that the barrel band does not keep barrel tight,it seems not to matter,the barrel "floats" within the band.

I also have that "problem" of not keeping zero.....I "used" to reset scope....Not anymore!,I now blame it on a cold barrel,or

a cold shooter,,,,shoot without doing anything and see if the rifle come back to zero,if not then adjust..

Also I should say .some of my PCP barrels are not snug,some are...I have a target pcp that the barrel is not snug yet it does not seem to matter,it stays on target...almost like the barrel has a memory where to be.

I also have the same rifle,never had that problem Good Luck finding a cure.

 

[Parrotculler]

Surprising, as the gun is not regged and cannot therefore suffer creep. Are you starting your shooting sessions at around 195 bars for a flat curve?

I suggest you start out with checking if the scope ring screws are all tight (don't overtighten either ...!) Then check if the barrel is tight in the breech without slop.

If the Zero shift persists, and the gun is not subject to significant temperature swings, it is likely to be a scope issue. What is the history of your scope? If you have ever used it on a springer you may have discovered your root cause right there. In that case you could do much worse than try the Marcool SF from you know where, or the even cheaper Diana 4-16*44 (front bell focus, illumination, 45 smackers, unbeatable price/quality ratio) from the same place.

Just like Troy I recommend against cutting off the barrel band. That is irreversible and likely to be unnecessary -- this short and rigid BSA barrel is unlikely to move in the band as long as you do not kick the gun around. Rather loosen or remove the attachment screw, and perhaps the o-ring, in the band. If you really want to remove the band, then unscrew the barrel at the breech and you'll be able to take the band off without destroying it. (The silencer as we know is not removable, so the band cannot slide off of the muzzle end.)

Good luck -- and welcome to the PCP troubleshooting club. It comes with the territory 

 

[melter942]

Surprising, as the gun is not regged and cannot therefore suffer creep.
1.) Are you starting your shooting sessions at around 195 bars for a flat curve?

I suggest you start out with checking if the scope ring screws are all tight (don't overtighten either ...!) Then check if the barrel is tight in the breech without slop.

If the Zero shift persists, and the gun is not subject to significant temperature swings,
2.) it is likely to be a scope issue. What is the history of your scope? If you have ever used it on a springer you may have discovered your root cause right there. In that case you could do much worse than try the Marcool SF from you know where, or the even cheaper Diana 4-16*44 (front bell focus, illumination, 45 smackers, unbeatable price/quality ratio) from the same place.

Just like Troy
3.) I recommend against cutting off the barrel band. That is irreversible and likely to be unnecessary -- this short and rigid BSA barrel is unlikely to move in the band as long as you do not kick the gun around. Rather loosen or remove the attachment screw, and perhaps the o-ring, in the band. If you really want to remove the band, then unscrew the barrel at the breech and you'll be able to take the band off without destroying it. (The silencer as we know is not removable, so the band cannot slide off of the muzzle end.)

Good luck -- and
4.) welcome to the PCP troubleshooting club. It comes with the territory 

1.) I refill to around 200 bar every fill and get 30 good shots. The first 5 shots on a fill often shoot a slightly looser group. This isn't a loose group. This is POI shift. Note the center row in my photo where I zeroed the scope. Each 2 shot group was pellet on pellet. I was aiming at the target on the right (marked FX Airguns Domed). 
Also, these were not the first shots of the session. I had shot one full air cylinder, 30 pellets at another target set at 50 yards. All grouped well, just not on the bullseye.

2.) The scope is brand new. It arrived the day before the gun. Both are only a couple weeks old and the scope has never been mounted on another gun.

3.) I won't be cutting or even loosening the barrel band just yet. My current plan is to first double-check all scope mounting hardware, then check the barrel to action fit.

4.) Thank you! The folks in this group are most helpful!

 

[Ripper]

I had forgot that that gun didn’t have a shrouded barrel. But it could be the barrel mounting screws that was already Mentioned. And I had the same problem with a scope that I had on a springer and then put on a PCP rifle would move Poi.

 

[melter942]

Don't rest or lean the barrel on anything.

Check to be sure the barrel is tightly securely mounted and won't twist nor pull out or in. Try testing if the barrel moves deliberately pull hard push hard and twist it.

Wedge a piece of PA Pellet tin packing foam between the stock and wall you lean it against if leaning the gun so the barrel doesnt touch anything.

You also want to tighten all the scope ring screws top to bottom and if it still does the POI zero problem the next time you shoot after all this and stop leaning the barrel against anything then time to change your scope.

Scope mounts are/were tight and secure.

I pushed, pulled and twisted the barrel as directed and I did not detect any movement where the barrel mounts to the action.
BUT... the following 10 groups were shot and POI adjusted by pushing the barrel in one direction or another. I very purposely moved the POI back to zero 2 times during this exercise, and never took the covers off the scope turrets. All adjustments were made by moving the barrel!

Can this be fixed? How can I affix the barrel to the action so it doesn't move so easily???

 

[variable]

I would double check your stock bedding screws make sure they are evenly tight. If this were a powder burner this would be a bedding issue. 

 

[AntwuanMaxx]

Went through the same with my Urban. Absolutely loved the rifle, but soon became frustrated with it after constant point of impact shifts. I didn't want to void the factory 5 year warranty by cutting the barrel band off, so I elected to disassemble the gun and remove the barrel, which allowed for the barrel band to slide right off without damaging it. This seemed to help, somewhat. Still experienced some poi shifts, but not nearly as dramatic as before. I usually rest all of my guns in my gun cabinet with the barrel resting against the cutouts for each slot. Once I stopped doing that and began resting the gun without any pressure on the barrel, the poi shifts pretty much went away. The only thing is now, without a barrel band, it can be knocked around and lose zero when hunting . Had this happen the other day while squirrel hunting, but still managed to bag a few squirrels after I figured out where to hold. I'm currently looking for an aftermarket barrel band to use while hunting for this very reason.

 

[Long_Gun_Dallas]

Any photos on how the barrel is mounted on this gun?

 

[Odoyle]

Don't rest or lean the barrel on anything.

Check to be sure the barrel is tightly securely mounted and won't twist nor pull out or in. Try testing if the barrel moves deliberately pull hard push hard and twist it.

Wedge a piece of PA Pellet tin packing foam between the stock and wall you lean it against if leaning the gun so the barrel doesnt touch anything.

You also want to tighten all the scope ring screws top to bottom and if it still does the POI zero problem the next time you shoot after all this and stop leaning the barrel against anything then time to change your scope.

Scope mounts are/were tight and secure.

I pushed, pulled and twisted the barrel as directed and I did not detect any movement where the barrel mounts to the action.
BUT... the following 10 groups were shot and POI adjusted by pushing the barrel in one direction or another. I very purposely moved the POI back to zero 2 times during this exercise, and never took the covers off the scope turrets. All adjustments were made by moving the barrel!

Can this be fixed? How can I affix the barrel to the action so it doesn't move so easily???

You can try to wedge a thin piece of material such as a feeler gauge Or make your own out of sheet metal door stop wedge in between the barrel and barrel band in 2 or more points to force it to stay in the proper position. 

 

[nitrowoodtic]

From my experience, your not going to stop the barrel from moving when bumped. What my goal was, is, to get the barrel to return to its natural position when pressure is released. The band restricts this on the Urban and Coyote. On my rifle, the band held the barrel below its natural position.


to remove the band on my rifle, I had to remove the breach / action from the air tube due to the barrel mounting set screws being on the bottom side of the breach.


The action is not as rigid as you might think. It flexes enough to throw off your groups. By moving the forward scope mount as far forward as you can, your using the scope as a stressed member of the assembly, reducing flex of the structure. This mainly helps once the barrel band is removed.