Lapping aliminium.

[Fat ferret]

Heathen! :x

 

[novocaine]

Thats what I did woodpig. lol love my wobley rider. Love my bsa airsporter too though, different horse for different course)
You want a skinny barrel try a crosman 1077. Like a peashotter. Clad in a curtain rail. You could bend it over your knee. Waste of space chunk of plastic. It didn't last long with me, was only bought for a laugh. Wasn't funny. Do have 1 plastic gun still but thats a joy to use.

Have you changed the breach seal? I've seen where a new seal makes it all feel solid but drops the barrel considerably because its not seated or to fat, often becuase its an old rifle with a modern metric seal in it). A light skim with an emery board to flatten the top was all it took to sort. (fairly sure it was a webley, cant remember)

 

[woodfarmer]

There are a lot of issues here. My feeling is the break lock may just be pointing too low instead of straight. if the rifle is under warranty may pay to take it back and compare it with another.
From there get it chronoed, as [power might be down. You could also try a lighter pellet as it will be faster.
also, maybe try turning the mount end for end.
as a last resort, bore the front mount ring say 3mm and have a bush made with the hole eccentric. the bush could be made from a bit of industrial black plastic such as acetal or nylon.

hope this helps

 

[Harbo]

What rifle is it and if you are breaking it in it must be new.
Also at 24ft/lb that's a powerful gun for this country - needs to be licensed

 

[monkeybiter]

the rifles running at 24ft/lb on ticket.

 

[woodfarmer]

Hi woodpig found the American sites but I note the special bar costs $50 and I would need to import one. I see your valve grinding paste on Ebay and it's around £5. Don't mind if it takes a while as I don't want to grind too much. Should work. Thanks very much.

Harbro I did think of that but unless I use an undersize bar it will be oversize. Thanks anyway.

Novocaine I am not underpowered the rifles running at 24ft/lb on ticket. Recoil is not bad but noticeably more than a 12ft/lb rifle. I can't turn around the mounts as they have an arrestor at the back that fits into the rifles dovetail stops. I can't buy an adjustable mount as I can't find one that fits my dovetail stops and want these to cope with the recoil. I have tried shimming the rear mount but still not enough. At 30yards I am just about have enough adjustment with some pellets I tried but far from ideal. If I shim any further I think I will run into problems with bending the tube. The problem is caused by the barrel pointing down but the lock up is solid. The barrel is not bent it's the breech causing the droop which is common enough even with top brands like hw.

I understand what your saying about other errors but have thought of this. My jig will mean the bar starts grinding at the front edge of the front cradle and I will slowly remove material until I have removed a small amount on the rear cradle and a little more of the front one. I only anticipate removing maybe 1mm from the front of the front cradle tapering to almost nothing from the rear of the rear cradle.
So the mounts should slope down. Then I can screw on the tops of the mounts. If the front one wont tighten up I may need to file it's feet very slightly. There is enough play in the screw holes that the top part wont bend the tube if I'm careful.

Sorry I did not see this post before I wrote my previous answer...

 

[Fat ferret]

Gave it a go.

Shot a group at a 10 meter target with the scope optically centred. 4" low and 1" to the right.

Got a fine file and filed a bit off the front cradle. Then used a 10" strip of 120 grit wet n dry wrapped round a length of 20mm copper pipe to smooth it off front and back twisting it round and round in the mounts. Remounted scope and the group moved an inch up. Repeated a few times and when it was an inch low I used some 240 grit wet n dry to finish it off. Had to file the front cradle arms slightly too.

Mounted scope is now shooting groups on target well within it's range of adjustment at 30 yards. The mount and scope tube meet up perfectly well.

Bit extreme but I now have mounts that have the arrestor system my rifle uses and look downwards a bit too. Not particularly difficult if you take your time. Thanks for all help and suggestions.

 

[monkeybiter]

Excellent result, well done!

 

[woodpig]

Nice job, glad it worked out ok. ccasion5:

 

[novocaine]

excellent. obviously without pictures it didn't happen, but we'll believe you this time.

 

[Fat ferret]

Did think of taking pictures but really not very exciting. Scope in place it looks like an ordinary scope mount.

Never lapped anything but as I removed around a mm of metal it would have took a while if I had .

 

[novocaine]

was more interested in seeing the grouping to be honest. lol

 

[Fat ferret]

Still searching out pellets as it's a bit more choosy being FAC power. Best so far are JSB, 1 1/2" @ 30 yards. Going to try JSB heavy which are 18.2 grain and have some on order.

 

[novocaine]

have you tried crosman premier ultra magnums, they are a heavy weight pellet that should suit (think a .22 is 14.3 grain so not as heavy as the JSB). nicely pressed without any flack, I use them in .177 (10.5 grain) and they've suited everything I own excluding the airsporter (not enough punch for weight). I like them enough to have bought 2 boxes of 1250 pellets instead of in tins.

 

[Fat ferret]

Ok here's a 45 yard 10 shot group of JSB exact 5.52. 9 shots went into 3/4" one had to go and spoil it. Could have been a damaged pellet, bit of lube burning off or just operator error!

[url=https://flic.kr/p/NiUdMx][img]...com/6/5573/30394980593_385c360494_m.jpg[/img]DSCF5393 by fat ferret, on Flickr[/url]

Zeroed at 30 yards shooting bang on target with plenty of adjustment left. I shot groups from 10 yards out to 45 to get an idea of trajectory now the gun is shooting at 20ft/lb. Shoots flat to 35 yards an inch low at 40 and 2" low at 45. Nothing comes close to JSB 5.52 for accuracy.

 

[Wildman]

Hi all. Bit of an odd one but maybe someone can help. Not a usual topic on here but it's still metal working. Will try to explain clearly for those not familiar with rifle shooting.

I am trying to zero an air rifle. The pellets strike the target low and the scope has run out of "up" adjustment. I want to try adjusting the scope mount which looks like this.

https://www.google.co.uk/search?q=s...S7AOIQ_AUIBygC&dpr=1.55#imgrc=Hk_-YHpdOcSitM:

I know I could end up wrecking the mount but want to try anyway.

My idea was to get a piece of 1" round steel bar, same diameter as the rifle scope. Jig the bar so it is rubbing against the front cradle of the mount and apply some cutting paste and rub the bar back and forth over the scope mount thus wearing away some metal mostly from the front cradle and a little from the back cradle. This will make the scope look "lower" where the pellets are striking.

I know there are other answers like shimming the rear cradle, which I have tried but still not enough. Adjustable mounts are available but for various reasons I don't want to use them.

If you didn't understand don't worry, you can still help . I need to know what lapping paste to use on the aluminium to cut it slowly that will work in conjunction with the round steel bar.

Thanks.

the easiest way is to just shim the scope mount. A cigarette paper is .0015 thou, (1 1/2 thousandth of an inch) maybe try a sliver of a coke can first. Save the accuracy of the mounts.

 

[monkeybiter]

A cigarette paper is .0015 thou, (1 1/2 thousandth of an inch) maybe try a sliver of a coke can first. Save the accuracy of the mounts.

0.0015" = 1.5 thou. Sorry, I can be a pedant at times.

 

[Fat ferret]

Wildman, In my original question, which you have quoted, I said I had already tried this but it wasn't providing enough adjustment. I don't mean to cause offence by pointing this out but maybe you should read the thread if your interested? Then again I doubt you have read my response so hopefully no offence will be taken.

 

[novocaine]

JSB are a mighty fine pellet and you only go to prove that.
I found that the s200 was picky about them though and would occasionally send a flyer, where as with the crosmans both the AA and the wobley were happy as larry. I'm putting the exacts through the airsporter at the moment, waste not want not. everyone has there preference when it comes to pellets. (the hw40 is a picky little thing but then it's only got a tiny barrel)

not a bad grouping you've got there, as usual though, 1 has to go and spoil it, only takes one breath and off it goes.