Zeroing

[Stealth Stalker]

I was out yesterday with Pin zeroing the .22lr after its recent circumcision

 

After getting some nice groups at 30 yds ( after winding it a hell of a long way left ) ,we moved back to my preferred hunting range of 50 yds & we were both getting some lovely groups, most of which were in the same holes Only problem was they were 20mm left of the aim point

So we wound it right about 8 clicks to get the same hole groups again but still wondering to the left a bit

 

I came back to the 30 yrd target and was even further left :o Surely at the closer target it should be nearer the center of aim point?

 

We were shooting in a small quarry so wind shouldn't of been the cause?

 

The only thing I can think of is the grip is quite awkward and I'm pulling the shot left?

 

Any ideas?

 

SS

[Dunkield]

I take it it has been chopped SS?

 

If it was OK before I would check what has been done to it, have a look at the crown, is there any obstruction at the muzzle end maybe?

[Stealth Stalker]

StuartP

 

Yes I had about 6 inches chopped ( I know thats some circumcition)

 

Just taken the mod off & there's a build up of dust & **** at the end of the muzzle?

 

I gave the rifle a good clean after I got it back.

 

SS

[Dunkield]

6 Inches! aye corumba that's a fair old chop.

 

What is the gun?

Are you sure the thread is true and the rounds aren't clipping the inside of the mod?

Try it without the mod, that will eliminate that.

[Stealth Stalker]

Its a cz brno, it went in for the chop because of the poor crown thread, its come back a hell of a lot better & shorter.

 

I've given it a few pull throughs with the boresnake & there's aload of **** in there

 

I won't have a chance to try it without the mod till the weekend is there anything else to try or look for?

 

Many thank SS

[Graham M]

If you are pulling the shots they would go right. Make sure you aren’t canting the rifle towards you and that the scope hairs are perfectly parallel to the bore.

If the vertical cross hair is leaning out as you look through the scope it will have the effect of causing the shots to go left, although saying that it would be worse the further away you placed the target.

Give the scope a light tap after you re-sight it in again.

G.M.

[Dunkield]

Get a picture of the muzzle up here if you can.

 

 

I've given it a few pull throughs with the boresnake & there's aload of **** in there

 

Black sort of lead residue **** or another type of ****?

[Stealth Stalker]

Stuartp

 

As requested some pics of the muzzle

 

The **** is of a fine gritty/ greenish variety

 

 

 

 

Hope these are ok

 

Cheers SS

[deadeye ive]

Can you get a better photo SS ............from these photo's the crown does not look like it's got a countersunk finish on the internal bore ..............easily rectified with a marble and some abrasive paste ........Not the point though if it's shoddy workmanship

[Devilishdave]

Looks like a bad job on the crown the finish should be as smooth as glass and the crowen nicely counter sunk. It has very similar results to a ben t barrel as well.

 

Dave

[kip270]

There dosen't seem to be a crown at all, take it back to the guy and get he to do it properly

[Stealth Stalker]

Cheers fellas

 

The crown has got about half a mm of countersunk finish on the end, you can't see it to well in the photo.

 

As for a smooth finish, its fairly rough.

 

I'm gonna play about with it at the weekend & if its still playing up its going back .

 

Cheers for the replies

 

SS

[Dunkield]

Unless anyone wants to contradict me, I think it should be 11 degrees?

 

I would.

 

Keep it simple, try zeroing it without the mod on.

 

If that goes OK, introduce the mod, the POI may change, but you should be able to dial that back in with a few shots.

 

If that doesn't work, stop there and take it back the man that did the work.

[Stealth Stalker]

Ok, Pin & me had another go at zeroing on Sunday first with the mod off at 30 yds, getting good 10p groups so mod back on & the same result (good groups)

 

Moved back to the 50 yrd mark & after a complte miss of the target And 8 clicks right we were both getting good 10p groups some shots same holes Confidence restored, before we left a fly was noticed on the 30 yrd target so for a bit of fun I had a go at it, COCK 25mm to the left, I then put another 15 shots and all were grouping 25mm left

 

I think it was Devilish dave that mentioned a bent barrel, could this be what I'm experiancing?

 

I ******* hope not

 

Cheers for all the help guys

 

SS

[Dunkield]

SS,

 

If it shoots OK at 50 yards and shoots 25mm left at 30 that sounds pretty heavy.

I have no idea what could cause that.

Looking at it logically, we are saying the bullet path is curved

 

I would suggest it is time to call in the big guns, have a word with GM,MRY, Devilishdave etc.

Let us know how it goes.

[CharlieT]

I can't tell what make of rifle it is from the picture.

 

 

Is the barrel floated or is there pressure on one side

Have you over tightened the action screw

Try it without the bipod as attaching the bipod may be causing the stock to bring pressure on the barrel.

Try a different scope and make sure it is fitted correctly.............my first suspect in this would be the scope.

Have you been doing as GM suggested and tapping the scope each tine you alter it. Try the scope out by counting the clicks and shooting a square and see if you end up where you started.

 

Keep us posted

 

Charlie

[pin]

I hope SS won't mind me answering while he's out at graft, might move things on a bit..

 

Its a BRNO

The barrel is floated

Don't know about the action screw, one for him to check

Using the bipod at 30yds, then moving to 50 (POI moves 1inch left) then returning to 30yds brings the POI back bang on ( I know, madness)

 

Again this is SS's thing but I have been there with him and seen this a few times. The scope is decent, a Leupold 3-9x40. Leaving the scope completely alone, with it zero'd and cloverleafing or tack driving at 30yds, if you move to 50yds without touching anything, same ammo batch, POI is 1" left. Again don't touch anything and move back to 30yds and POI is spot on.

 

If it were the scope surely the POI wouldn't return to dead centre at 30yds would it?

 

I have a theory that it will be further left at 70yds, if POI is 2" left then it has to be a bent barrel?

 

Just some other random thoughts, it's not clipping anything, too consistent and does the same without the mod. Its not something one shooter is doing wrong, we have both fired 100 rounds+ each trying to sort this out, from prone. The reticule in the scope is nice and thin and we can see the aiming point perfectly.

[MC]

Pin,

 

Your theory is correct, if the barrel is bent then the error will get worse the further out you go. Although 1" to the left for another 20yds sounds excessive in reality it isn't.

 

A bullet does not fly straight in its lateral axis, It will actually fly in a large right hand spiral. Just because you have moved back 20yds it doesn't necessary mean that the POI will just be low. The only thing for certain is it will be different.

 

When I target shoot at 15yds my sights are bang on, when I move to 50mtrs they are alomst the same, just a couple of clicks higher. This is due to the bullet rising at 15yds and dropping through the same point at 50mtrs.

 

But left to right is normally a long way out to the left.

[CharlieT]

Good post Pin, you have answered all my questions and I now understand your problem.

Talk about frustrating, I think indeed that we are getting to the stage where one has to question the straightness of the bore.

I think the time has come to return the rifle to the supplier.

It does not seem that there is any variable left to check and this problem really seems to be one of manufacture or damage.

 

Charlie

[pin]

I guess there is the action screw to check, but I don't know enough to know if that could cause what is happening here?

 

No doubt SS will read this thread at some point, will mention to him to try at 70yds and see if it's further left - if it is then we are saying its definitely bent?

[MC]

I would be suprised if it is the action screw as this would play havoc with the grouping. It would in no way be consistent.

 

Still it wont harm it being checked.

[CharlieT]

I don't think in this case the action screw will have any bearing. All the problems I have had over the years I've only come across this when I bent the barrel on an old .22 when it fell out of the rear of a tractor and got run over.

So yes...............bent

[pin]

Thanks to all who have replied with advice and help!

 

Hope SS is having a good day, I am fairly sure he won't want to hear this

 

That said, it wasn't bent before he had the gunsmith chop / re-cut & crown it so I guess he'll be on to them

[MC]

You could always give it a bang to the right! You probably can't make it worse. Or split the difference and zero it at 40yds, it will only be 1/2" out left or right then.

[Devilishdave]

Next stage is to view the barrel, if you se an non uniform shadows in the form of a cone going off to one side then it is a bent barrel. when you view a barrel ensure you have both eyes open and dont try to use the barrel as a telescope and hold the barrel about 12 inches away. view from both ends and turn 90 degrees at both ends.

 

Dave