Remington Summit--puzzling accuracy problem

[kkoenning]

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

[longislandhunter]

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

[kkoenning]

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.

[longislandhunter]

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

[tjk]

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

[kkoenning]

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

[kkoenning]

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?

[longislandhunter]

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

[moon]

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..

[kkoenning]

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.

[longislandhunter]

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

[shadow]

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

[kkoenning]

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.

[longislandhunter]

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

[kkoenning]

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.