# Gamo Big Cat, sighting scope issue



## avv604

Greetings all,

I have just purchased my first air rifle and first rifle with a scope. The scope is a Gamo 3-9x40.

Since I have never attempted this before, I searched the internet and found several ways to sight in a scope.

At 10 yards I finally got it sighted in to where three shots were almost in the same hole. Now, I would move the target back to ~20 yards and tested again.

Side note: I zoomed in the scope to maximum for each shots at 10 and 20 yards.

At ~20 yards I could not get anywhere close to the target. The hits were 3" to the right and each additional shot went about 1/2 to 1" below the previous shot almost in a straight line.

So, after a couple of days of trying to get it working at 30 yards and 10 yards... I am not sure what the issue is.

Ideas?


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## Ambush Hunter

Is your parallax set correctly? - Does that scope have an adjustable objective?
Is it mounted properly?
Are the stock screws tight?
Are you using an "artillery hold"?
Do you "follow through"?
Are you squeezing the trigger and not jerking?
What is the trigger pull like?
What rings do you have on the gun?
Have you tried to shoot at a lower magnification?
What pellet do you use?
What do you use for a rest?

More than often accuracy suffers due to improper shooting techniques. The farther you shoot, the more frustrated you get. The gun+scope you have is of mediocre quality at best, but still capable of 1" groups at 30 yards.


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## avv604

Ambush Hunter said:


> Is your parallax set correctly? - Does that scope have an adjustable objective?
> Is it mounted properly?
> Are the stock screws tight?
> Are you using an "artillery hold"?
> Do you "follow through"?
> Are you squeezing the trigger and not jerking?
> What is the trigger pull like?
> What rings do you have on the gun?
> Have you tried to shoot at a lower magnification?
> What pellet do you use?
> What do you use for a rest?
> 
> More than often accuracy suffers due to improper shooting techniques. The farther you shoot, the more frustrated you get. The gun+scope you have is of mediocre quality at best, but still capable of 1" groups at 30 yards.


*Is your parallax set correctly?* Yes-I would presume

*Does that scope have an adjustable objective?* Can you please let me know what the objective is.

*Is it mounted properly?* Yes, according to the directions.

*Are the stock screws tight?* Yes. Without question. 

*Are you using an "artillery hold"?* Not sure of this type of hold. Please explain.

*Do you "follow through"? *Since I am new to air guns and rifle firing altogether, can you describe more fully as to what you are asking? 
*
Are you squeezing the trigger and not jerking? *Squeezing, according to articles I have read on the internet.

*What is the trigger pull like?* Easy and then tough toward the end, then it snaps back (which of course is when it fires)

*What rings do you have on the gun?* Can you provide more information as to what "rings" are and how one finds them? Please remember the label I currently carry regarding air guns, which is "newbie."

*Have you tried to shoot at a lower magnification?* I have. I started out, on the first attempt, on "3" and sighted the scope in at 10 yards and then tried ~20 yards. I did not have much luck so I zoomed in the scope. That did help but it was still not as tight of group.

*What pellet do you use?* Gamo Raptor.

*What do you use for a rest? *I took a backpack and put clothing in it. This provided a rest for most of the gun, except the stock. I then took the scope caps and used the small end to put the stock in (not sure what to call the small protrusion at the bottom of the stock). With this setup I was pretty stable. 
I know sand bags are recommended but I did not want to spend another $100 just to sight in a scope.  With this setup I did not have to touch the gun really as it would stay in the same spot and easy to get back to the same spot after a reload.

I am aware this gun is not the "best of the best." However, I should be able to get, as you mentioned, 1/2 to 1" groups... not 3-6" groups.

*Does this aid in the attempt to help this newbie?*


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## blowgunner62

Your problem could be the Gamo raptors. They are much lighter than other pellets. This makes them shoot faster, but they are inherently inaccurate because of their light weight and instability in flight. (Anyone feel free to correct me if I'm wrong.) Also don't rest your air gun directly on a sandbag or other rest. I know it does make the gun steadier but spring-piston guns tend to group poorly this way.

For the pellets you'll just have to see what works in your particular gun.

Suggested pellets to try:

Crosman Premier hollow points

Beeman coated hollow points

There are a lot more out there than just these. Pyramid Air (www.pyramidair.com) has many different kinds of pellets that you could try, but don't go crazy buying up thousands of pellets of the same variety. Instead, get a couple of different tins and then buy more of the ones that shoot accurately in your gun.

Hope this helps.


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## Ambush Hunter

AO (adjustable objective). Does it have a ring on the front that you turn in order to get a sharp view? If not, there is a possibility that this scope has a parallax set at longer distances. If that's the case, you have a parallax error. Do a little test. While looking through a scope, move your head up and down, left to right. Does the reticule also move with you moving? If so, you have an error.

Spring piston airguns are notorious for being inaccurate if held in an inconsistent manner. An artillery hold is when you hold your rifle losely, let it move while it's going through a firing cycle, another words, let it breathe. Don't hold the stock too tight to your shoulder. Everything counts here, the way you put your cheeck on the stock, the way you exhale, squeeze the trigger, etc. 
Pyramydair.com have some good articles in their library on spring piston guns. Do a search.

Since the "lock time" on springers are relatevely long, compared to PCPs and Gas-Ram piston guns, the "follow through" is also important. Lock time is the term that describes the time frame between the trigger tripping the sear and the moment when pellet leaves the muzzle. So since this time frame is longer, you have to try to stay on target after firing. You have follow through the whole process.

I suspect you have rings that came with a scope. (rings that scope sits in on your gun).

Now, do yourself and your gun a favor and through away those Gamo Raptors. They are too hard for the barrel and too light to be accurate. Go to pyramydair.com and purchase good quality German and Chezh pellets.
Raptors are only 5 grain and more that often go supersonic or close to that. Pellet that is fired at supersonic speeds becomes unstable hence inaccurate. Don't even question that. It would be a good idea to put your rifle through a chronograph. You need to choose heavier and higher quality led pellet. What's more important, a bit less velocity but more accuracy or a hyper velocity with accuracy down the toilet? Sometimes by choosing a heavier pellet, even though your velocity drops, you gain extra energy in return, and energy is what you really need.

Get Beeman FTS, Kodiak, and variety of JSB pellets. Always choose a dome shaped pellets since they have better ballistic coefficient than hollowpoints, pointed, and wadcutters.

Generally, hard rests are not suited for spring piston guns. You need something cushy underneath the front of the stock. Sand bags -no. Forget what you know about firearms, because airgunning is a whole another science. Try putting your palm between the rifle and your back pack. Just rest it there whithout grabbing.

For right now my quess is that it's either a scope or a pellet that gives you problems. Most likely pellets. Change your ammo, work on your mechanics, and go from there.


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## avv604

All,
Wow, thank you so much for the advice. I know very little about shooting a rifle and it sounds as if I have a whole lot to learn.

I also have purchased Gamo Pro Magnum pellets (750). Since I am clueless as to what to get I just searched for the best and got those. So perhaps I need to purchase some hollow points?

Also, last night I was asking my father-in-law (big hunter, etc) and he gave me some oooooold pellets that are very dull and made from lead.

They are flat on the end. I believe they are called "wadcutters"?

Is there any article links regarding how to shoot these types of guns I can go to and read? 
--I did go to pyramydair.com but I am having a bit of difficulty in finding articles to which apply to my newbie situation.


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## avv604

I found this article. It seems to address a few of my questions. 
http://www.pyramydair.com/blog/2009/03/gamo-big-cat-part-4.html

Are they any others that might help out the newbie?

Thank you all for your responses so far.


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## avv604

Ambush Hunter,

To now answer your question "Are you using an "artillery hold"?" No sir, I am not. I have read a blog posting ( http://www.pyramydair.com/blog/2007/07/artillery-hold.html) and it explains how to hold it.

Thinking back, at 10 yards I was holding the gun looser. However, when aiming at 20 yards I tried to tighten it to make sure the gun would not move.

I also think the ammo is part of the problem too.

I have some homework to do!! 
Thanks all!


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## Ambush Hunter

Do not buy hollowpoints. Dome pellets have better aerodynamics. Throw those that your father-in-law game you away. Throw away Raptors, too.

Good luck :beer:


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## blowgunner62

Hollow point pellets will do just fine if you find one that shoots accurately in your gun. Like Ambush Hunter said, put something soft (your hand) between the gun and your rest. This is extremely important with a spring gun.


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## avv604

Well,
I tested the different hold this morning and re-sighted the scope in to 20 yards. It was not much of an adjustment and I was seeing smaller groups. However, there was an occasional stray. The strays I now chalk up to my incorrect holding of the gun.

I just now watched the video of the artillery hold. NOW I see what the posts are about and understand better.

The gun seems pretty accurate, if the user will practice. 

This morning I used the Gamo Pro Magnum pellets, they seemed to be ok.

One other item I have noticed. After each shot now there is smoke in the barrel. I can blow the smoke out after each shot. What is that?

Lastly, it appears the inside of the barrel needs cleaning. What type of "cleaning kit" is recommended?

Thanks again for the wonderful help.


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## avv604

Ambush hunter,

My apologies as I never answered you question. 
*AO (adjustable objective). Does it have a ring on the front that you turn in order to get a sharp view? * Yes sir. I got the Gamo Big Cat with the 3-9X40 AO scope.

Another term I am unfamiliar with is parallax. What does this mean?


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## Ambush Hunter

You can read about parallax and parallax errors here. You can also google it.

http://www.6mmbr.com/parallax.html

The "smoke" in the barrel is what called dieseling. It happens a lot in new spring-piston rifles. The reason - too much of lubricant, tar, and greese. Some of this stuff gets in the compression chamber and barrel, and burn upon firing. Dieseling goes away on its own, all you have to do is to shoot the gun often. Nothing to worry about. Or you can disassemble the rifle and clean spots that needs to be clean leaving lubricated what needs to be lubricated. Usually it take several hundreds of shots for dieseling to stop.

*DO NOT *use hard brushes and rods for airgun barrels. Only soft pull-throughs. If you do choose a rod, make sure it's covered with soft plastic.

Generally, airgun barrels do not need to be cleaned as often. I only clean it when the accuracy starts to suffer. Even then, I eliminate other reasons before I mess with a barrel.

*Never Ever *fire a spring-piston gun without a pellet in the barrel. *DO NOT* shoot hard steel darts either.

What do you see in the barrel that makes you think it needs cleaning?

GET SOME HIGH QUALITY GERMAN PELLETS! They are not just better consistency-wise, but also cleaner.


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## avv604

Ambush Hunter said:


> GET SOME HIGH QUALITY GERMAN PELLETS!


I am getting the idea about purchasing some quality German pellets.  Is there a name brand is can search for or just Google for German pellets?

Thank you for the advise. Wonderful tips for the newbie. 

Ok, pull through cleaners... will do. Thanks again.


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## Ambush Hunter

Pellets:

pyramydair.com
straightshooters.com
airgunsofarizona.com

You will not find good pellets at wal-mart or bass-pro. You have to use one of those web dealers. There are many others of course. These are top three off the top of my head.

Here is an idea how accurate spring-piston airguns can be. First, .177 Air Arms TX200HC and two groups, one at 25 yards - one hole 5 shot groups. Second is a 50 yard group, it is right at 1" on a good calm day.

Then .20 Beeman R9 at 30 yards - right at 0.5"

And third, a .22 Air Arms TX200MK3 at 30 yards - right at 0.5"


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## fprefect

avv604 said:


> Greetings all,
> 
> I have just purchased my first air rifle and first rifle with a scope. The scope is a Gamo 3-9x40.
> 
> Since I have never attempted this before, I searched the internet and found several ways to sight in a scope.
> 
> At 10 yards I finally got it sighted in to where three shots were almost in the same hole. Now, I would move the target back to ~20 yards and tested again.
> 
> Side note: I zoomed in the scope to maximum for each shots at 10 and 20 yards.
> 
> At ~20 yards I could not get anywhere close to the target. The hits were 3" to the right and each additional shot went about 1/2 to 1" below the previous shot almost in a straight line.
> 
> So, after a couple of days of trying to get it working at 30 yards and 10 yards... I am not sure what the issue is.
> 
> Ideas?


I don't know if your scope and instructions are the same as mine, but both the scope and the instructions for adjusting the windage is *backward.*

Also if your scope is the same as mine,(Gamo??) that has no adjustment f for parallax on the objective lens, and shooting indoors at a range of only
30 ft or so, even if the ocular is turn counterclockwise to it's limit and the power is set to 3X, there is still enough parallax to change the point of impact by as much as 1/2". The only way over avoiding this is to be sure your eye is perfectly centered behind the ocular lens. If there is any vignetting (blurring) near the edges of the field of view, your eye is not centered and will result in a different impact point. At longer ranges, this parallax is not present to nearly the same extent.

F. Prefect


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## spentwings

> Ambush Hunter said:
> 
> 
> 
> Here is an idea how accurate spring-piston airguns can be. First, .177 Air Arms TX200HC and two groups, one at 25 yards - one hole 5 shot groups. Second is a 50 yard group, it is right at 1" on a good calm day.
> 
> Then .20 Beeman R9 at 30 yards - right at 0.5"
> 
> And third, a .22 Air Arms TX200MK3 at 30 yards - right at 0.5"
Click to expand...

Missed this thread...that's fine shooting with a springer AH!


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