Darno Posted May 14, 2013 Report Share Posted May 14, 2013 Hi This might be a stupid question but I have a sub 12ft lbs air rifle that I use for a bit if pest control. A friend gave me a lovely scope but it won't zero in, The vertical adjustment is dialled all the way down but it's still shooting about 3 1/2" high. My verdict is that the scope won't zero inside 50yrds. My question is - can I shim either the front or back of the scope up to bring it into zero, and if its shooting high then which do I shim?? Any replies would be great! Thanks Pete Quote Link to comment Share on other sites More sharing options...
harry69koi Posted May 14, 2013 Report Share Posted May 14, 2013 Im no expert but i would say you need to shim the mount closest to your eye piece m8ty,to bring the rear up a tad Quote Link to comment Share on other sites More sharing options...
secretagentmole Posted May 14, 2013 Report Share Posted May 14, 2013 (edited) OK now this may surprise you but you can have front and rear mounts, so first centralize the scope, count how many clicks the adjuster turns and then turn it half way! Swap the mounts round and replace the scope. Is it any better? Harry is wrong. You need to lift the front of the scope UP, so shim the front mount. Plastic is very good for this and 35mm film negatives ideal! Using packing get it as close as possible! Then use the adjuster to get it spot on! If you bring the rear up, it will move the cross hair lower! Edited May 14, 2013 by secretagentmole Quote Link to comment Share on other sites More sharing options...
Dekers Posted May 14, 2013 Report Share Posted May 14, 2013 Hi This might be a stupid question but I have a sub 12ft lbs air rifle that I use for a bit if pest control. A friend gave me a lovely scope but it won't zero in, The vertical adjustment is dialled all the way down but it's still shooting about 3 1/2" high. My verdict is that the scope won't zero inside 50yrds. My question is - can I shim either the front or back of the scope up to bring it into zero, and if its shooting high then which do I shim?? Any replies would be great! Thanks Pete What is this lovely scope that does not appear to want to zero? As above secretagentmole, shim the FRONT if it is shooting high, but just the same something seems VERY wrong here at airgun distances. Quote Link to comment Share on other sites More sharing options...
pauleamonn Posted May 14, 2013 Report Share Posted May 14, 2013 ........so shim the front mount. Plastic is very good for this and 35mm film negatives ideal! Alternatively, if you don't have any thin plastic or film negative to hand, you can use folded foil. Quote Link to comment Share on other sites More sharing options...
Darno Posted May 14, 2013 Author Report Share Posted May 14, 2013 It's a BSA sweet 17, the dial on the top says 17hmr so I imagine its not designed for a sub 12ft lbs springer:-) Will try above suggestions and see if it brings it into zero. It's bang on left to right and if I allow for the fact it's shooting high then it's bang on! Quote Link to comment Share on other sites More sharing options...
bruno22rf Posted May 14, 2013 Report Share Posted May 14, 2013 (edited) Cut a piece off a used 12g cartridge case and pack the mount nearest the barrel-mole was pretty much on the button as ever Edited May 14, 2013 by bruno22rf Quote Link to comment Share on other sites More sharing options...
Capital Bee Posted May 14, 2013 Report Share Posted May 14, 2013 Found this : Quote Link to comment Share on other sites More sharing options...
bigman Posted May 14, 2013 Report Share Posted May 14, 2013 If its shooting high surely you need to raise the rear mount to bring the poa down to allow for adjustment? Shimming and raising the front mount will only make it shoot higher, Quote Link to comment Share on other sites More sharing options...
goodo123 Posted May 14, 2013 Report Share Posted May 14, 2013 If its shooting high surely you need to raise the rear mount to bring the poa down to allow for adjustment? Shimming and raising the front mount will only make it shoot higher, I was thinking the same.... Quote Link to comment Share on other sites More sharing options...
pauleamonn Posted May 14, 2013 Report Share Posted May 14, 2013 (edited) Actually, Mole is correct. If you think about it, the line of sight to the target (what you see through the scope) is being crossed from below to above by the pellet. That is shown by the fact that the pellet is striking high. This means that the front of the origin of the line of sight (the scope) needs to be raised in order to make the point at which the line of sight hits the target coincide with the POI of the pellet. Hence the need to pack up the front of the mount. Edited May 15, 2013 by pauleamonn Quote Link to comment Share on other sites More sharing options...
weihrauch hw100 Posted May 14, 2013 Report Share Posted May 14, 2013 prob easyier to pay 35 quid for a cheapy scope that will solve all ur problems Quote Link to comment Share on other sites More sharing options...
Darno Posted May 15, 2013 Author Report Share Posted May 15, 2013 prob easyier to pay 35 quid for a cheapy scope that will solve all ur problems That's crossed my mind.-) shame, it's such a nice scope!Will have a play about with it, if I can get it to work them great but if not was thinking about a nikko sterling mount master! Quote Link to comment Share on other sites More sharing options...
pauleamonn Posted May 15, 2013 Report Share Posted May 15, 2013 Darno - have you done as suggested by Mole? It would be a shame to lose the opportunity to use such a nice scope due to not trying all the options. Quote Link to comment Share on other sites More sharing options...
Dekers Posted May 15, 2013 Report Share Posted May 15, 2013 (edited) If its shooting high surely you need to raise the rear mount to bring the poa down to allow for adjustment? Shimming and raising the front mount will only make it shoot higher, I was thinking the same.... Sorry, but as already said that is incorrect. In effect the scope is straight but the barrel is pointing up now, so to bring the POI down the FRONT mount needs shimming, this will have the effect of lowering the barrel. But as I have already said, something more fundamental is wrong here! Edited May 15, 2013 by Dekers Quote Link to comment Share on other sites More sharing options...
weihrauch hw100 Posted May 15, 2013 Report Share Posted May 15, 2013 That's crossed my mind.-) shame, it's such a nice scope! Will have a play about with it, if I can get it to work them great but if not was thinking about a nikko sterling mount master! ive got a spare nikko scope if your interested.it works fine i just upgraded.id let it go for 15 quid.cheers Quote Link to comment Share on other sites More sharing options...
secretagentmole Posted May 15, 2013 Report Share Posted May 15, 2013 The problem is that the scope is designed for a .17 HMR (Hornady Magnum Round). These fly like the proverbial bat out of hell with optional rocket boosters! So the extra speed will equate to extra height, which is why the scope won't centre! IE if your pellet was bombing out at the speed of an HMR round it would impact higher (remember we aim using an arc shaped trajectory)! Quote Link to comment Share on other sites More sharing options...
chrisjpainter Posted May 15, 2013 Report Share Posted May 15, 2013 That's crossed my mind.-) shame, it's such a nice scope! Will have a play about with it, if I can get it to work them great but if not was thinking about a nikko sterling mount master! Just had a read of the brochure for the Sweet 17. this is the key line: 'The Sweet 17 is specifically calibrated for the 17 grain HMR bullet, and marked for ranges from 100 to 300 yards' Shimming might compensate for that range change, but as suggested get something designed for airgun ranges with a reticle to match - something like a mil-dot scope is ideal. Quote Link to comment Share on other sites More sharing options...
secretagentmole Posted May 15, 2013 Report Share Posted May 15, 2013 (edited) I already made that point, well sort of! I was in the same area! Edited May 15, 2013 by secretagentmole Quote Link to comment Share on other sites More sharing options...
timmytree Posted May 15, 2013 Report Share Posted May 15, 2013 The problem is that the scope is designed for a .17 HMR (Hornady Magnum Round). These fly like the proverbial bat out of hell with optional rocket boosters! So the extra speed will equate to extra height, which is why the scope won't centre! IE if your pellet was bombing out at the speed of an HMR round it would impact higher (remember we aim using an arc shaped trajectory)! If the extra speed of the HMR round means extra height then surely that means the problem is even worse? The OP can't adjust the POI down far enough with a sub 12 that comparitively speaking has a trajectory like a brick fired by knicker elastic. It seems to me as though it's a scope or mount problem or even something more serious like a bent barrel. What gun is it on, break barrel, underlever or PCP? Quote Link to comment Share on other sites More sharing options...
chrisjpainter Posted May 15, 2013 Report Share Posted May 15, 2013 I already made that point, well sort of! I was in the same area! Yeah I know; I was in the process of typing an almost identical post to yours when you beat me to it! So, I had to put something extra in - like a quote from the BSA brochure, which I had to download purely to include that one line. Wow, it was definitely worth it. Quote Link to comment Share on other sites More sharing options...
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