GTA
General Discussion To Gateway To Airguns => China Gate => : kkoenning January 06, 2009, 02:29:55 PM
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I have about 400 to 500 shots thru this gun and recently (about the last 50 shots) the shots have dropped 1/2 inch and right maybe 1/8 to 1/4 inch. The grouping is still the same as it was (dime size or less), just down and right of where it was shooting. Of the three springers I have (Remington Summit, Crosman G1, and Gamo Big Cat 1200), this one had been the most accurate.
The gun is as supplied from the factory except for a GRT-III trigger. I am shooting indoors at 25 feet from the target and using the same pellets (Crosman premier hollow points--from the same tin).
Did my scope go away? AFAIK it has not moved.
Did something happen to the gun? Breach seal looks very flat?
Thanks in advance for any suggestions.
Puzzled
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Did you re-sight in the scope and if so is it holding zero or is the POI continuing to change ????
Are the last 50 shots from the same batch of pellets or are they new pellets ???
I'm just throwing stuff out here.
Jeff
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I have not touched the scope adjustments since I sighted-it-in 400 to 500 shots ago.
The last 50 shots are from the same batch of pellets (a tin of 500--only a few left now). I settled on the Crosman hollow points because they were the most accurate and made the tightest groups.
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If it's holding it's "new" POI and still maintaining consistent dime sized groups I would venture to say your scope / mount setup has probably shifted a bit due to the recoil of the gun. Either that or your stock screws loosened up a bit.
Check both, re tighten stock screws and scope mount screws using blue loc-tite,,,,,, give the loctite 24 hours to dry and cure and see what happens.
I'm sure some of the others will chime in with other suggestions, but my best guess is the stock screws or scope mount screws......
Jeff
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Jeff's probably right on this one. I experienced the same things with my quest variant. I would just add that if you haven't already, you should get it tuned!! It will make your rifle alot more enjoyable too shoot!! Best of Luck! tjk
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I checked the stock screws and they were tight and I had used blue loc-tite when reassembling after I installed the GRT-III.
All of the scope mount screws seemed tight and I did use blue loc-tite when I first assembled the scope to the rifle.
Not sure if it is holding its new POI, I will have to check it today.
Any other suggestions?
TIA
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Yes, it is the stock scope. It is a crosman 3-9 x 40 AO and it uses a one-piece mount. Four cap screws are used to clamp onto the dovetail and four cap screws (smaller) on each ring. The stop pin is screwed down into the stop pin hole in the gun.
If the scope is moving, is it likely to be slipping to the rear or front? (I am a newbie--hope this is not a "dumb" question.)
I will have to remove the scope to see if the stop pin has slipped or did not hold its position.
Visual inspection (without removing anything) does not seem to indicate slippage. Perhaps the scope is failing?
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Take a fine lined pencil and make a mark on the receiver in line with the front and rear of the scope mount. Then take the pencil and trace a line on the scope tube on both sides of the 2 top straps. Now take the rifle out and shoot for awhile. After your done shooting look at the pencil lines. If theres been any movement, either the mount or the scope tube in the rings, you will be able to see if the pencil lines have "moved".
Whenever I mount a scope on a new rifle, or a new scope on an old rifle, I always mark them this way so that I can always tell if there's been any movement at all.....
Just a suggestion...........
Jeff
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If rifles gain velocity when you "break them in," the point of impact should change too, shouldn't it? A lot of things happen in that short period. Lubes move around, the barrel gets smoothed out with friction, the seal seats itself etc..
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I decided to remove the scope. It appears as if it MIGHT have moved on the receiver--maybe 1/32 of an inch toward the rear. Don't know if it moved in the rings or not.
I will remount using blue loc-tite as I did initially. This time however, I am modifying the stop device. I am removing the stop set screw which was cone shaped and would only go into the hole in the receiver a very small amount. Since hole in the receiver is threaded, I am going to use a flat head screw through the mount (after cutting a countersink in the mount) and into the threaded hole in the receiver. This will also be loc-tited.
I will also take longislandhunter's advice and put pencil marks on the receiver and scope tube so I can keep an eye on any movement.
After the loc-tite sets up, I'll rezero the scope and post my results--if anyone's interested.
Thanks to all.
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Before you re-mount the scope make sure you clean the top of the receiver, dovetail grooves and all surfaces of the scope mount and the scope tube with denatured alcohol. After doing that then go ahead and do your re-mount with the blue loc-tite. I have a feeling it may solve your problem....
As for posting your results after re-mounting,,,,, please make sure you do cause I'm certainly interested in the results and I'm sure the others who responded are also......
Will be looking forward to your upcoming post :)
Jeff
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Jeff's spot with that advice and I do the same thing, I mark key area's on the scope to mount and mount to receiver area. I can tell in a second if any of the above moves at all.:) Keep us posted. Ed
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Well, I re-zeroed the scope after a remount. The group is just as tight as before. I originally had to add 90 clicks of "up" on the scope elevation; now I had to add an additional 35 clicks of "up". Windage adjustment was 15 clicks of "left"--originally had added 20 clicks of "right".
Newbie questions here: Isn't 125 clicks a lot? How much before I run out of adjustment? How will I know I have run out of adjustment.
Thanks in advance.
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Now that you've got the rifle re-zero'd spend some time and shoot it. Keep an eye on those pencil marks you made to track any scope/mount movement.... If you don't get any movement and your zero holds then you've got the problem licked......
As for knowing when you've run out of elevation or windage.................that's easy,,,, you won't be able to adjust the POI as far as you need to because the dials simply won't turn anymore.....
Let us know what happen. I'll keep my fingers crossed for ya.
Jeff
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Yesterday I shot 40 shots and they were excellent--less than dime size groups right on the intended POI.
Today it is now shooting the same tight groups but now 3/4" high and 3/8" left of the intended POI. I looked at my marks on the receiver and the scope tube and it HAS NOT moved!.
I have to believe the scope is faulty. Guess I will be calling Crosman on Monday morning. The gun is about 5 weeks old.
Thanks.
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Interesting,,,, first time it was shooting low and right,,,, now it's shooting high and left,,,,,, I think you've discovered the problem. I've never dealt with them but I've always heard that Crosman is very good about warranty, repairs and that sort of customer service thing. Let us know how it turns out. At least you found out the problem......
Jeff
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I had a similar problem with my RS2 and the Leapers 3-9X32 AO scope that I put on it. I found that my groups would get farther low and left the longer I shot until they ended up 1" low and 1" left at 25 yards. When I'd give up for the day and then come back out the next day (or later the same day) it would be spot on at first and then got low-left again. If I adjusted for the low-left POI then when I would come back out the next time I would be shooting high-right for a while. It finally dawned on me that it was a 70 ° day when I zeroed and on the days that I saw the shift it was in the 30s. After being inside for a while the scope would warm back up and shoot the original POI. I checked the forums here and found several references to shifting POI with temperature. If if Crosman used the Centerpoint scope in that combo then its possible that it might be the same thing. I see that you're shooting indoors and I haven't done any testing to see how dramatic the temperature change needs to be to cause the POI shift, but temperature might be something worth checking.
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Welcome to the GTA forum kkoenning and bearded_spock. You beat me to it, I was thinking of temperature changes also. Not only that, I've read a thread about how you lay the gun down...ie. left or right side can also affect POI...strange huh? I had the POI change on my Gamo Viper a few months ago.....one night I was shooting 1/4" dots 8 out of 10 times at 10 meter distance all night. Next morning (Less than 6 hours in between) I went down to the basement to shoot again....I couldn't believe it....all my shots were 1/2" low. Nothing moved...I checked all the marks on the scope and scope mount. So I had to "click" the elevation knob about 20 times to get back on target. After that everything's fine. I think in my case it was the gun settling down. Hope that's the case for you as well kkoenning. Or maybe it is the scope's fault.
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After reading through the various replies, my money would be on the ambient temp affecting your scope. When I take my rifles outside to shoot, I usually lay them on a beach towel on top of the picnic table. Then I walk away and let it sit for a while and give the scope time to aclimate itself to the outside temps. Sometimes I'll even 'flip it over' and let it lay for a little longer if the inside and outside temps are really different. This Is a great time to grab a cold one out of the fridge, play with the dogs,.....feed the dogs, take a load of trash out, etc.......you get the picture. It took me a long time for me to realize this little trick, but the results have been alot better than before. If your Summit came with the same "Crosman" ( Relabelled Center-Point), that my SP came with then I wouldn't exchange it for another one just yet. Their pretty good scopes for a "combo'd" rig. If anything, I'd try another one piece mount and see how things go. I had to get an adjustable mount to keep my scope rets centered in the scope, then I only had to give it a few clicks to get her zeroed. But give the "let her rest" method a try and see if things turn out better,....I hope they do!!!, tjk :emoticon:
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I called Crosman this morning. They told me to send the scope in and they will replace it. So, I boxed up the scope and took it to the UPS store. Now I just have to wait for the replacement.
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kkoenning - 1/7/2009 9:10 AM
Yes, it is the stock scope. It is a crosman 3-9 x 40 AO and it uses a one-piece mount. Four cap screws are used to clamp onto the dovetail and four cap screws (smaller) on each ring. The stop pin is screwed down into the stop pin hole in the gun.
If the scope is moving, is it likely to be slipping to the rear or front? (I am a newbie--hope this is not a "dumb" question.)
I will have to remove the scope to see if the stop pin has slipped or did not hold its position.
Visual inspection (without removing anything) does not seem to indicate slippage. Perhaps the scope is failing?
When mounting a scope don't discount the fact that it needs to be plumbed as any variance will throw your shoots side to side and when mounting read on proper install > http://www.pyramydair.com/site/articles/scopes-part2/ :)
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Hey Keith, Dealing with these Gremlins keeps the pellet makers in business it seems.Been there, done that. A new scope mount would be on my wish list if I were you. You may be using so much of your scopes adjustments to get POA to POI at the '25 ft distance your shooting at that the scope can't hold the reticle firm.It wanders 'cause it's in the "mushy" end of it's adjustment range. An adjustable mount would allow you to compensate for elevation and windage adjustments without adjusting your scopes windage or elevation adjusters.Keeping the scope very near it's optical center will help eliminate it's likelyhood that the scope is the cause for wandering groups.But that temperature thing,definitly for real. Your gun is only" sighted in""for the temperature and conditions you are shooting on that particular day. Zero'd at 75 deg. ain't necessarily Zero'd at 35 deg.Also your gun is still new. Not unusual to need several hundred shots for the gun to wear in and stabilize.Also, believe it or not, you might benefit from a barrel cleaning.Some guns do.Good luck with your replacement scope and if the same old problems persist, get a better scope and mount.
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Replacement scope arrived today. Total time was 10 days (8 business days). Pretty good!
I installed today and will zero it in tomorrow. I'll let you know how it goes.
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Replacement scope is zeroed and have maybe 50 or 60 shots through it.
Seems to be holding--so far. I will post if I have any problems with the replacement scope.
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Agree with progun, get drooper mounts or adjustable mounts, try to start with scope as near center optically as possble. John
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Friday my shots were low and right just like with the original scope--maybe a total of 100 shots now. According to the marks on the scope tube and the receiver, scope has not moved. Zeroed and shooting in the basement with constant temperature. I have re-zeroed but I expect it will change again.
Maybe I can try some adjustable mounts--anyone have any suggestions for affordable adjustable mounts?
Any suggestions for a reasonably priced ($60 - $70) scope that is known to be reliable on springers? Guess the Center Point supplied with the Summit just cannot handle the recoil of this springer!
Thanks in advance for any suggestions.
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Keith, is your rifle tuned yet?!? If not, you'd be well advised to make the investment on one. A real good Adj. mount is the Beeman 5039 model,....made by the Sports Match company. It's pricey, but very solid and reliable. That scope you have is quite adequate, but the re-coil of an untuned springer will cause just about any shooter to have doubts in his scope!!!! LOL's Have you installed a GRT-III trigger on your rifle?!?!? That will cut your accuracy issues in half even without a tune!!!! Good Luck. tjk
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Wow, lots of thoughts on what could be doing this, but what about this? How many times do we put our cheek down on the stock in the EXACT same spot? I found that a lot of unexplained POI changes came not from defective equipment but from me! Mark the stock for a cheek rest, zero in to that, and then see if using that same spot, EXACTLY the same spot, each time, results in better POI. It has been my experience defective equipment POI changes are not as perfect, resulting in scattered hits rather than just moved groupings.