Barrel Misalignment

[vivek009]

Dear all,

After about 400 rounds with my new Crosman, I realised that while my shots group well even out to 35 yards, all the shots seem to be placed on the right side of the bullseye (or on the right half of the paper target). Out of the box, the rear sight was set a few notches on the right side of the slide scale, so after each group, I moved it a bit left to make the impact point shift left. I kept on doing that till I reached the dead center of the slide scale. That, I thought, should be the place to keep the rear sight. But even that didn't solve the problem, so I kept on moving the sight to the left of slide scale center. The impact points did shift left.

However, I thought to myself that if the front sight is right on the center of the barrel/muzzle and the rear sight is also placed in line (in short, everything is absolutely straight), the rear sight must be kept on center of the slide scale to hit dead center on target. However, if eveything is not straight, the rear sight will have to be moved to right or left to compensate.

Indeed, looking closely at the barrel, I could see that the barrel is ever so slightly "bent" to the right. However, this bend can only been seen at the muzzle. I am sure this slight bent can be compensated for using the rear sight. Only that the sight will have to be moved too far out in one direction. But, then this does not feel comfortable. Have you guys ever faced such a problem? How can one "straighten" the barrel?

Looked at CharlieDaTuna's site. There is a method given there to correct for barrel misalignment. But that is absolutely brutal, and I don't have the heart to perform that on my air rifle.

Any suggestions would be greatly appreciated.

regards
Vivek

[snIPer]

" Looked at CharlieDaTuna's site. There is a method given there to correct for barrel misalignment. But that is absolutely brutal, and I don't have the
heart to perform that on my air rifle. "

Hi can you please paste a link for that site - i would like to know more about the method used

[dev]

groups to the right may be due to the trigger squeeze and the way you are holding your spring air rifle. Normally they are hold sensitive, so before you make a gun that can shoot around corners check these possibilities out .
dev

Dear all,

After about 400 rounds with my new Crosman, I realised that while my shots group well even out to 35 yards, all the shots seem to be placed on the right side of the bullseye (or on the right half of the paper target). Out of the box, the rear sight was set a few notches on the right side of the slide scale, so after each group, I moved it a bit left to make the impact point shift left. I kept on doing that till I reached the dead center of the slide scale. That, I thought, should be the place to keep the rear sight. But even that didn't solve the problem, so I kept on moving the sight to the left of slide scale center. The impact points did shift left.

However, I thought to myself that if the front sight is right on the center of the barrel/muzzle and the rear sight is also placed in line (in short, everything is absolutely straight), the rear sight must be kept on center of the slide scale to hit dead center on target. However, if eveything is not straight, the rear sight will have to be moved to right or left to compensate.

Indeed, looking closely at the barrel, I could see that the barrel is ever so slightly "bent" to the right. However, this bend can only been seen at the muzzle. I am sure this slight bent can be compensated for using the rear sight. Only that the sight will have to be moved too far out in one direction. But, then this does not feel comfortable. Have you guys ever faced such a problem? How can one "straighten" the barrel?

Looked at CharlieDaTuna's site. There is a method given there to correct for barrel misalignment. But that is absolutely brutal, and I don't have the heart to perform that on my air rifle.

Any suggestions would be greatly appreciated.

regards
Vivek

[Mark]

My apologies if this has been discussed before, but what model crossman is it?

[Mack The Knife]

Mark,

It's a Crosman Quest. Made in China.

http://www.indiansforguns.com/viewtopic ... c&&start=0

Mack The Knife

[vivek009]

groups to the right may be due to the trigger squeeze and the way you are holding your spring air rifle. Normally they are hold sensitive, so before you make a gun that can shoot around corners check these possibilities out .
dev

[/quote]

Thanks for reminding about the trigger squeeze Dev. I am aware that if the squeeze pressure on the trigger is not uniform, the shots could hit right or left of the target, depending upon which side of the trigger the pressure is more.
It is hold sensitive alright, and I do try to hold it as lightly as possible and the same way each time. However, I am still perfecting it, and that could be the cause of the problem.

Mark,

It's a Crosman Quest. Made in China.

Mack The Knife

Yes, it is actually the Xisico B-19 (XS-B19) made in China, sold in US by Crosman under the brand name "Quest".

regards
Vivek

[Mark]

Ahh OK, just googled it.

So it is a break barrel then.

As Mack The Knife mentioned, one of the first thing to do with a poor shooting gun is to have someone else shoot it for a while! If it does the same thing to them that is does to you or if it does something different are imortant things to know and help find the problem.

Now I must apologize again, but to make sure I understand this, is the bore offset on the muzzle end? As if it was not drilled on center?

Is this what your front sight looks like:



The simplest thing would be to reposition the fiber optic element over the bore. The nicest looking would be to make a new banded front sight with the offset built in so it wouldn't be that noticeable.

You can check the straightness of a barrel by stretching a fine wire through the bore and holding it against the sides, if the bore is not straight you'll see it.

[vivek009]

Mark, Thanks.

The bore is drilled straight alright. The problem is that I think, relative to the receiver, the barrel is not absolutely straight i.e. the receiver and the barrel are very slightly misaligned, if at all. The problem is best expressed in the picture below (this is not a picture of my gun, I found it on net, but this explains the misalignment well):

[albumimgl]59[/albumimgl]

Since the "bent" is to the right, I think it could be taken care of by moving the rear sight to the right on the windage scale. But there must be some way to put the barrel and receiver in line with each other.

regards
Vivek

[Mack The Knife]

Vivek,

To check if the barrel is ever so slightly bent, either use Mark's method or look straight through the bore from the breech end. If you see a perfect circle then the barrel isn't bent. However, if you see an ellipse, however slight, then the barrel is bent. If so, I can tell you how to fix it though I personally haven't tried doing this.

If the centre of the breech block - barrel assembly is not aligned with the centre of the cylinder - you claim that it is right of centre, in which case you should try shimming. The shim (circular washer) will have to be placed between the breech block and the breech block jaws (on the right side in your case). The barrel pivot pin/bolt will pass through the shim.

Incidentally, before you do any of this check that all your stock screws are tight and do a few test groupings.

Don't try shimming the breech block or straightening the barrel at this point of time. Let me know how the rifle groups after you have tightened the stock screws.

Mack The Knife

[Mark]

Vivek,

It sounds funny, but the barrel being mis-aligned will not cause the gun to shoot to the side as you describe since the sights are mounted on the barrel.

You can check barrel misalignment be removing it from the stock and putting it on a flat counter top, or table. First lay the gun on the right side and then the left. You could also use a rule and measure the difference in height at the muzzle and use a sine table to get the angle of misalignment.

However, realize that since the sights are on the barrel, if the sights were proper it would still shoot even if the barrel were angled 10 degrees unless the problem is where the barrel fits to the breech block. If that is the case it will really go crazy when you mount a scope, but on the other hand I suspect someone who is careful with a hydraulic press could straighten this without much difficulty.

[shahid]

Try a different make of pellets. It might help. Instead of Crossman, say use GAMO and see how they group.

[vivek009]

Thanks Rusty and Mark.

Let me first carefully look through the bore and see if its a perfect circle. Although I remember seeing a circle while cleaning the bore. If it isn't, however, will get in touch with you Mack The Knife. Unfortunately, I don't have any pellets other than the GSmiths, so cannot test with different pellets. As for the stock screws, they are, while not loctited, but have been screwed in with Permatex blue (equally good I suppose).

Yes you are right Mark, the sights are mounted on the barrel. Hence the sights, relative to the barrel, will be straight no matter how much bend is there. But I think the problem is at the breech block or it could also be that the barrel is straight, but the front sight is very slightly rotated in one direction. Difficult to tell just by visual inspection. If nothing else works, I think I'll remove the front sight and put it back on with as much precision as possible. Only thing is, the front sight is pressed on the muzzle, and will not be easy to remove.

regards
Vivek