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View Full Version : Zero at 35yds 3" to the left at 55 yds?



Meerkat
23-05-2004, 06:31 PM
Ok Guys,

I know there's a simple explanation, but I don't know it :(

At 35 yds I can get everything within a 5p piece. But at 55 yds it's well to the left, (and no, there wasn't any wind). It's also consistently off to the left.

Is this something to do with scope alignment, i.e. I've either not got the scope reticule exactly vertical/horizontal or I'm not holding the rifle vertical, (you know what I mean - I'm not pointing it straight up!)?

Looking at the reticule, it looks to be correct, and how much rotation of the gun do you need to get 3" the left at 55 yds when it's zeroed at 35 yds?

Cheers,

Steve

BoNeS
23-05-2004, 06:36 PM
i am interested in this too as i had a similar problem a while back with another scope

The Golden Shot
23-05-2004, 06:39 PM
your scope may be canted, Marks all to aware of this ;)

only jokin m8:D

dwb
23-05-2004, 06:40 PM
look like you got something called crossover
to put it simply the scope does not line up with the barrel
suggest packing one side of the scope rail
DWB

wkhudson
23-05-2004, 06:49 PM
I agree on the crossover. To test this you need to get that 35zero nailed down to one hole in zero wind. Then, make a pellet hole in something ten yards away. Shoot your next pellet at that hole. Carry on for five more pellets.

If the pellets form a trend going to the right (opposed to your leftward trend at 55) then you've got crossover.

Problem is, the amount of deviation will be harder to spot at ten yards than at 55.

Paul Hudson
23-05-2004, 07:15 PM
I'm with Dave and Wayne.

Instead of packing the rail though, you could try turning one of the mounts around so that it's clamped on the other side. See whether this makes the problem better or worse.

It can also be caused by cheap mounts - spending a bit extra on the mounts pays dividends in eliminating crossover.

It's also worth checking that you've tightened the top clamps down evenly - try measuring the gap with feeler gauges.

HTH.

Paul.

Beer Hunter
23-05-2004, 07:42 PM
Yep, totally agree with the others.
If it were cant, with .22 you would have to be out by about 14 degrees and in .177 about 22 degrees!

TERů

Darren Petts
23-05-2004, 09:44 PM
Check your barrel is straight with the air cylinder. The fig of 8 clamp can hold it off to the side if it's had a whack.

swamprat
23-05-2004, 10:35 PM
When I had this problem there happened to be a thread on here where someone suggested that, to check for crossover, remove scope, leave bottom clamps on and place a knitting needle in bottom of curve to check alignment with the barrel. I used a welding rod - a far more manly solution - it's a crude method, but I saw that my scope was way out.

Turned one of the clamps round but it didn't work.

Bought some BKL centreline mounts (available BAR I think). Should have sorted the problem... but...

...and there's always a but with such problems...

...I discovered that, when I adjusted the parallax on my scope (an Airmax), the POI would change. Sent scope back; got another; not much improved. Resorted to standard scope.

Now did the BKL sort my problem out, or was it the changing of the scope? I honestly cannot say, but now that I've got it sorted I ain't changing anything.

To muddy the waters still further (sorry), with a non-parallax adjustable scope, failure to seat your cheek on the stock in exactly the same position for 55yds as for 35yds will cause an offset aim. But I think the latter problem may cause a more scattered grouping (or to be more precise, a couple of mini groupings within a larger group) rather than a neat offset.

Sorry for the rambling, it's just the mood I'm in tonight. Hope at least one piece of some of what I've offered may help.

Scarecrow
24-05-2004, 08:54 AM
If you can't suss out the crossover or cant, a short term fix would be to set your windage turret whilst shooting at 55 yards. You will be out at 35 yards as a result, but due to the shorter distance, the difference will be a lot less than 3 inches.

Assuming everything else is consistant, I reckon the above fix would have you grouping 2 inches to the right at 35 yards. Not much of a solution is it!? :(

Enzo
24-05-2004, 10:20 AM
Steve - just a thought - are you adjusting the focus (parallax) when you change between 35 and 55 yards? I had a scope where changing the parallax would change the POI. Actualy it was not the POI changing - it was the point where the crosshairs were lining up on the targe which changed. :rolleyes:

The reason I ask this is because I find it difficult to get my head round the crossover theory. If you are zeroed at 30 and out by (say) an inch at 60 yards - then assuming light and pellet travel in straight lines (pellet when viewed from above ), then your scope would have to be 1 inch out from centerline. Or am I missing something?

ATB Gordon

woody2906
24-05-2004, 10:37 AM
I've had this problem too, being left handed i used to secure the scope mounts with the allen bolt on the left hand side of the rifle having been told it didn't matter which side they were secured.

It does matter! As has been said try different combinations of securing the scope mounts.

max headroom
24-05-2004, 10:59 AM
not often i get to comment on the general section.
before anyone says thank christ, i`ll say it for you.:rolleyes:
i had a mk1 superstar for ages, fitted with 3-9by40 tasco silver antler. it was attached by low single mount. never a problem.
i now have a mk2 with 3-9by50. attached with two piece high mounts. lots of problems. the bsa dampa system doesnt like it.
it might be worth a few quid to get a one peice mount and see if it makes a difference.
since i went two peice i have to check it every time i go out. the one piece stayed true all the time.
just a thought though, if you have iron sights use them now and then. this makes you hold the rifle in a fashion you will take up. irons won`t allow you to cant, as wont diopters.

Enzo
25-05-2004, 08:15 PM
Steve - if you do eventualy suss this problem out - can you post back on here as I'd be interested to know the cause - (probably speaking for the others too)

ATB Gordon

jools27666
25-05-2004, 08:33 PM
Originally posted by BoNeS
i am interested in this too as i had a similar problem a while back with another scope

did you have it on the right way around ? :D :D

FLEETY
25-05-2004, 08:57 PM
smiler
I have also had this but being a novice could not sought it out,
I have got MK3 & tried to set eveything up as I proceded bang on @ 35 yds & worked my way out to 55 yrds & be hold fine but all shots were going to the right ( help I thought to my self but took advice & try different pellets) Which I did & behold as I was shooting & 55 yrds with a different pellet (which I found to be the correct one for the gun) & getting dead on groups I worked inward yardage wise & found all was OK after that. It may be the answer i do not know but I still think to my self why do one make of pellets shot to POI to others. Hope this helps
Fleety

submariner
28-05-2004, 05:20 PM
I was interested in this problem.
Buying some new mounts the sportsmatch say they fit 9.5 to 11.5 mm dovetails. As they only clamp on one side I checked my dovetail width. Hmm it was 11mm. So I think that means the scope will be 0.5mm out of line with barrell i.e. 0.5 to the left of the barrel or am I missing something?
If so then I must be setting the scope windage to aim right a little at say 20 yards [if this is my zero] - So therefore when I aim at 60 yards will I only be 1.5mm off to the right theoretically or am I off with my theory

Jon Budd
28-05-2004, 10:21 PM
Originally posted by submariner
If so then I must be setting the scope windage to aim right a little at say 20 yards [if this is my zero] - So therefore when I aim at 60 yards will I only be 1.5mm off to the right theoretically or am I off with my theory

Exactly - not too big a deal is is ? ;)

To work aroud the prob, you could zero the gun so it's 1/2mm off, then it wil always be 1/2mm off at any range :)

nath
02-06-2004, 06:17 PM
i would never pack a scope on the side but if your scopes on the cant try setting it up with a level downrange and one on your gun always works for me or your barrels bent

Tigger C
02-06-2004, 06:24 PM
It doese'nt take much of a breeze to shift the point of impact at fifty five yards! Come to think of it doese'nt take much of a wobble to produce this problem either, or poor trigger technique either. No offence, just trying to be constructive :)
Regards
Chris.