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scope mounting

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dvlnme View Drop Down
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    Posted: 05 Jun 2017 at 9:16am
Not airgun but still realent,changed the scope mounts on my 22 lr double rifle yesterday and didnt 
 align cross hairs correctly to both bores which find important on this type rifle,but you get same effect
 i ended up with often using high mounts required for the big scopes many us use on air rifles that i ended 
 up with on double rifle only on double rifle its worse.
 If scope not square to the vertical line the barrel cross hairs will not be horozontal to bore,as the eye 
 bassically automatically levels the cross hair the barrel will end up pointing to one side,the rifle will be 
 canted to one side or the other,possible to sight rifle in,but usually only at one set distance as will then
 shoot to one side or other at other distances,we have am sure tryed other guys rifles and thought the
 scope wasnt aligned correctly i am sure.
 Effect is evan worse with double rifle due to having two barrels with bores some distance appart scope
 is aligned between the barrels,if scope not aligned to the horizontal of both bores,the effects when
 shooting get interesting for sure,as i found out,this rifle regulated to put both barrels at 50 yds into
 1inch circle,two groups approx 1/4inch apart which is normal grouping for this type rifle,but what i got
 was very different,because rifle was canted,left barrel was being twisted up and to left unknown to me at
 time,sighted using right barrel as allways did,got bang on,fired left barrel,shots went hi n to the right,now 
 thats not usual nor correct,never happened before,had me stuffed eh!!removed scope,shot rifle with open
 sights,was bang on,must be getting dumber as get older coz still didnt figure it out,blaming scope,but
 new scope,so unlikely to be scope eh!!but still hadnt sunk in DURRRR!!
 Took me 6 beers n lasers to figure it out wen got home and i shouldve known right away eh.
 Brought this up as had friend turn up while back with pcp rifle n large scope he couldnt get shooting
 as it shouldve,problem was exactly same as double rifle,scope not aligned correctly to bore,not first
 time found this problem caused otherwise very accurate rifles to have unexplained accuracy issuses
 when shooting at longer distances,and can rear its ugly head with the hi mounts we use for larger 
 scopes on our airguns today.
 Cheers Mike
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Novagun Quote  Post ReplyReply Direct Link To This Post Posted: 05 Jun 2017 at 9:57am
I have always tried to get my air rifle scopes mounted as exactly as I can. I use a spirit level to get the rifle mounted exactly level in a home made vice. That can be a bit of an arbitary level because I don,t know how true the machining of any flat part sight as the top of the beach block is or the two flats on either side of the stock.
In plastic stocks I think it is not too good. Some rifles dont have any flat bit to balance a level on.
Next I mount the scope, after having optically centered the cross hairs, and then level up the scope using a spirit level sitting across the top of the elevation turret cap. Tighten the machine screws on the rings in a criss-cross pattern. Finally check the scope alignment using a plum bob with the rifle at the shoulder.
I also  check by eye that the vertical hair bisects the back of the compression tube exactly, and at the same time the ocular lens. 

Bang-- Bullseye every time. 

The Americans report aiming at a mirror and making sure that the vertical cross hair exactly bisects the muzzle. I got a mirror a while ago but have not yet tried it. Wet day so I will try it today.

Double rifle, I suppose that could be under and over or side by side. And one or each barrel just a little bit off perfect sight in.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Flub Quote  Post ReplyReply Direct Link To This Post Posted: 05 Jun 2017 at 5:44pm
I have spirit levels that fit to the dovetails to getmy rifles level, then spirit level across turret as Novagun says.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote dvlnme Quote  Post ReplyReply Direct Link To This Post Posted: 14 Jun 2017 at 8:01am
setting scopes up correctly never been easy for me am just so fussy,the new larger scopes many us using
 on our airguns today means higher mounts etc putting scope higher still above the barrel etc, and  harder
 to set up correctly eh!!
 The eye i think automatically seems to align cross hair to horizontly,and if bore not exactly vertical to 
 that horizontal will be canted to one side and as distance increases point of impact moves further to that
 side and can become a real issuse eh.
 i hace a scope ring now with built in level that works great for setting up my scopes now,i set rifle up now
 in rest ,adjust until its level using this ring,remove ring ,fit scope and align cross hair with a level line i 
 have marked on a wall,end result both rifle n scope perfectly aligned.
 the double rifle a real pain as botth barrels allso need be horizontal as. i use two cheap laser pointers one
 in each barrel and align lasers with horizontal line on wall,then mount scope and align with horizontal 
 line as well,works beauty as both scope n barrels are aligned horizontally.
 Before i figured this out for the doubles they were really difficult to get shooting right with a scope.
 cheers Mike
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Post Options Post Options   Thanks (0) Thanks(0)   Quote xyon Quote  Post ReplyReply Direct Link To This Post Posted: 22 Jun 2017 at 4:18pm
I'm probably not as anal as I should be about aligning the scope cross hairs, I kinda do what novagun said and align the vertical cross-hair line with the centre of the compression tube. When I do this I move my head (eye) back so there is only a small bright circle visible. This lets me centre my eye and eliminate any parallax error between the cross hair and the compression tube.

I was wondering if anyone laps the mounts with a bar? I have used a 24.7mm bar wrapped with sand paper to remove a mm from the front mount to compensate for barrel droop.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote nunga Quote  Post ReplyReply Direct Link To This Post Posted: 22 Jun 2017 at 4:24pm
I have tried that with sandpaper. didnt do squat :)
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Post Options Post Options   Thanks (0) Thanks(0)   Quote xyon Quote  Post ReplyReply Direct Link To This Post Posted: 22 Jun 2017 at 4:31pm
I managed to remove sufficient metal from an aluminium mount. I wouldn't want to try with stainless steel mounts Cry
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Pauly5 Quote  Post ReplyReply Direct Link To This Post Posted: 22 Jun 2017 at 6:44pm
The other option is to pack up either the front or back with a thin material, though too much would create uneven pressures. Or buy Nungas adjustable mounts.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote dvlnme Quote  Post ReplyReply Direct Link To This Post Posted: 25 Jun 2017 at 6:20pm
got some adjustable mounts on my 22 rimfire double rifle,was only way could get barrels n scope
 properly alinged on bloody thing,mine quite old prob not as flash nungs eh,but they worked n that all
 that all mattered i guess.
 Cheers Mike
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