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 Posted: Tue Aug 03, 2010 3:21 pm |
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| Alstone |
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| Joined: 01 Mar 2007 |
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| Location: Linconshire, ENGLAND |
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A buddy of mine brought a QB78 down for me to have a look at, evidently some pellets shot well and others such as Superdomes went anywhere. So I had a look at the crown which seemed ok and nothing was lose and moving about, so I put a few AA fields through it and they were spot on but other pellets I tried went all over the place.
One thing I did notice was that when closing the bolt you had to push hard for the last little bit, something not required on my QB, so I whipped out the barrel to have a better look inside and the culprit was found.
The lead in for loading the pellet should be smooth as if feeds in to the rifling, but on this gun there was a step, and on some pellets it was shaving a bit off the pellet nose as it was pushed into the breach.
A little bit of emery on a stick and spun in a drill soon smoothed out the lip, and now pellets load very smoothly and Superdomes plus others which didn’t shoot well are spot on.
You can see where a bit as been sheared off the pellet.
The lip inside the barrel can just be seen.
Al |
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| Posted: Tue Aug 03, 2010 4:44 pm |
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| AirGunEric |
| Site Admin |
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| Joined: 20 Jan 2007 |
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| Didn't a few people around here have other issues with QB barrels- i.e. bent out of shape, crowns that were ragged and rifling that was damaged? Seems the QB factory needs to keep track of quality control a bit better... |
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| Posted: Wed Aug 04, 2010 3:46 am |
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| Alstone |
| Moderator & Site Supporter |
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| Joined: 01 Mar 2007 |
| Posts: 4139 |
| Location: Linconshire, ENGLAND |
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I have had a QB for 3 years now and it never shot properly because of a faulty barrel, so I bought another barrel from Archer airguns, on this one the hole came out so far off centre it was impossible to line a scope up with it, it was eventfully cut down to 7” and used on a 2240 with good results.
Back to the original barrel it was in a hell of a state with score marks and ribbing grooves all down the bore, but It has now come good.
A friend of mine had a endoscope for deep hole inspection and this we used to map out the bore damage, we found out that there was a good 5” section 2” down the barrel from the muzzle, so after chopping off the 2” and doing a quality re-crown the QB now does 6mm groups at 20m, and is now my favourite light weight gun. 
Al |
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| | | | | | | | | Faulty Barrel | | | | | |
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