Weihrauch HW100 T has become completely inaccurate

[Lavant_Lad]

Have you got a friend you can swap barrels with for 1/2 hour?

[Rapidnick]

I will admit to not having read every single post on this thread so I may well be repeating advice already given. As a general rule a deterioration in performance from a quality air rifle like the HW100 means either 1)the barrel needs cleaning 2) the barrel is loose 3) the moderator is causing the pellet to clip so test without the moderator or 4) try different pellets. In addition as a specific issue with the HW100, the 'figure of eight' barrel clamp may be causing a problem so try a test with the clamp removed.

[jepho]

I will admit to not having read every single post on this thread so I may well be repeating advice already given. As a general rule a deterioration in performance from a quality air rifle like the HW100 means either 1)the barrel needs cleaning 2) the barrel is loose 3) the moderator is causing the pellet to clip so test without the moderator or 4) try different pellets. In addition as a specific issue with the HW100, the 'figure of eight' barrel clamp may be causing a problem so try a test with the clamp removed.

Thank you for your response: 1) done 2) done 3) done 4) done

The barrel band does not appear to be restricting the barrel and it serves to hold the barrelled action into the stock at the front end. It may be possible to nip it up far tighter than is desirable and bend the barrel and hold it bent. I guess the torque required to do that would be significant. Until I removed the barrelled action, there was no previous removal of the barrel band and no obvious reason for its retaining bolt to have tightened itself. I will let my gunsmith know that this is a thought that requires some investigation.

[Rapidnick]

Thank you for your response: 1) done 2) done 3) done 4) done

The barrel band does not appear to be restricting the barrel and it serves to hold the barrelled action into the stock at the front end. It may be possible to nip it up far tighter than is desirable and bend the barrel and hold it bent. I guess the torque required to do that would be significant. Until I removed the barrelled action, there was no previous removal of the barrel band and no obvious reason for its retaining bolt to have tightened itself. I will let my gunsmith know that this is a thought that requires some investigation.

Sorry for my late response to your post replying to mine. I'm not convinced that the barrel clamp isn't responsible so I strongly recommend you remove the barrel clamp entirely and run the gun with a free floating barrel. It is odd to think that a barrel can deteriorate without explanation to the extent you have experienced. Certainly any idea that the power plant is at fault can be confidently discarded.
Good luck-it must be very frustrating for you.

[Amac]

In addition to the wise advise already provided, I would strongly recommend an "intensive" barrel cleaning process with something like VFG blue paste/felts. I have seen many barrels brought back from the dead following a good seeing too with this cleaning regime. I also know of several top shooters who have resorted to using the infamous copper brush coated with cleaning paste to achieve the same outcome, although I am personally not brave enough to be so aggressive with an airgun barrel.
Andy

[Shed tuner]

I also know of several top shooters who have resorted to using the infamous copper brush coated with cleaning paste to achieve the same outcome, although I am personally not brave enough to be so aggressive with an airgun barrel.
Andy

have done this a couple of time, with great results, but only on barrels that I was ready to scrap, so had nothing to lose. Not recommended in any other situation really.


And it helps to have a lathe to machine a new one if needed

[jepho]

have done this a couple of time, with great results, but only on barrels that I was ready to scrap, so had nothing to lose. Not recommended in any other situation really.


And it helps to have a lathe to machine a new one if needed

Did you forget the power feed, the gun drill for coolant, a coolant capable lathe, the travelling centre and the four jaw chuck?

[jepho]

Sorry for my late response to your post replying to mine. I'm not convinced that the barrel clamp isn't responsible so I strongly recommend you remove the barrel clamp entirely and run the gun with a free floating barrel. It is odd to think that a barrel can deteriorate without explanation to the extent you have experienced. Certainly any idea that the power plant is at fault can be confidently discarded.
Good luck-it must be very frustrating for you.

Thanks for your response. Will the free floating barrel have a better chance of being accurate? My sense was that the barrel band is just providing an attachment point to ensure that the barrelled action is fixed to the stock at two points. If I leave the band off the barrel, is there no other point that holds the action and barrel into the forestock?

The barrel deterioration has been relatively sudden, with no warning that the barrel was becoming defective in some way. Why can the power plant be eliminated as a possible culprit? Frustration is a very good word and it describes my lack of understanding... perfectly. Thanks for the good luck wishes.

[Shed tuner]

Thanks for your response. Will the free floating barrel have a better chance of being accurate? My sense was that the barrel band is just providing an attachment point to ensure that the barrelled action is fixed to the stock at two points. If I leave the band off the barrel, is there no other point that holds the action and barrel into the forestock?

just try it, to see if it sorts the problem. if it does, we can think about the long terms fix...

[jepho]

just try it, to see if it sorts the problem. if it does, we can think about the long terms fix...

Thank you. I will see what the gunsmith uncovers. If I have no choices left, I will consider removing the band. I am struggling to understand how an 18 month excellent performance (with the band) requires the band to be removed in the hope it may change something that did not need changing previously. /pedant

[Rapidnick]

Thanks for your response. Will the free floating barrel have a better chance of being accurate? My sense was that the barrel band is just providing an attachment point to ensure that the barrelled action is fixed to the stock at two points. If I leave the band off the barrel, is there no other point that holds the action and barrel into the forestock?

The barrel deterioration has been relatively sudden, with no warning that the barrel was becoming defective in some way. Why can the power plant be eliminated as a possible culprit? Frustration is a very good word and it describes my lack of understanding... perfectly. Thanks for the good luck wishes.

I am used to a free floating barrel on my Rapids and I have run a HW100 with the clamp removed and it was fine as the barrel is located pretty firmly in the action.. Will it work? The answer is 'I don't know' but barrel clamps can get disturbed or knocked and as stated by Jon, removing it and testing is a zero-risk strategy so you might just as well do it. A few minutes work and nil financial outlay has to be worth while. In any event if it isn't the clamp is will probably end up being diagnosed as the barrel itself which will cost you a few bob to get fixed. It is certainly also worth checking that the two parts of the action have not become loose. One of the major criticisms of the HW100 is that the block is in two parts bolted together with not particularly heavy duty 4mm hex bolts. They shouldn't be loose but again always worth checking when you have the action out of the stock.

[jepho]

I am used to a free floating barrel on my Rapids and I have run a HW100 with the clamp removed and it was fine as the barrel is located pretty firmly in the action.. Will it work? The answer is 'I don't know' but barrel clamps can get disturbed or knocked and as stated by Jon, removing it and testing is a zero-risk strategy so you might just as well do it.

A few minutes work and nil financial outlay has to be worth while. In any event if it isn't the clamp is will probably end up being diagnosed as the barrel itself which will cost you a few bob to get fixed. It is certainly also worth checking that the two parts of the action have not become loose. One of the major criticisms of the HW100 is that the block is in two parts bolted together with not particularly heavy duty 4mm hex bolts. They shouldn't be loose but again always worth checking when you have the action out of the stock.

Thank you for this helpful response and your input.

There is only one single angled grub screw holding the barrel into the action. One bolt holds the stock against the action and the bolt through the barrel band holds the fore-stock against the cylinder. I can see that the testing of the barrel without the band holds little risk and it would be worth testing the issue while the gun is shooting like a shotgun.

If my gun were to come back from the gunsmith and fund to be shooting absolutely accurately, then there would be (to my mind) less value in testing the gun in this way. I am working on the assumption that all parts of any design have a specific purpose and removing any of them can presage and unwanted effect. I did check for the integrity and tightness of the bolts holding the two parts of the action together and they seemed to be as tight as required.

Whatever may lie behind the gun failing to produce the accuracy to which I am used to seeing; I am inclined to agree with you that the issue lies within the barrel in some manner. I am prepared for the costs involved and I will try to look after my gun differently if it can prevent the same thing. For now, I have to wait and see what the gunsmith can achieve.

[jepho]

Have you got a friend you can swap barrels with for 1/2 hour?

Sadly, No. Where the barrel is mated to a specific action at the factory, is this pathway likely to encourage inaccuracy? I cannot be sure what test this provides and what the outcome would tell you.

[rockdrill]

Where the barrel is mated to a specific action at the factory, is this pathway likely to encourage inaccuracy? I cannot be sure what test this provides and what the outcome would tell you.

I would hardly call an HW100 barrel 'mated' to the action, these are 'assembly line' guns not hand built specials. A barrel will be taken from the rack and inserted to an action and the grub screws tightened to lock in in place.

By changing barrels it could well indicate whether your barrel has developed a fault or whether it is a power plant issue.

[jepho]

I would hardly call an HW100 barrel 'mated' to the action, these are 'assembly line' guns not hand built specials. A barrel will be taken from the rack and inserted to an action and the grub screws tightened to lock in in place.

By changing barrels it could well indicate whether your barrel has developed a fault or whether it is a power plant issue.

Thanks for the helpful response.

I don't have a barrel to exchange. All guns must be tested to some degree at the factory and signed off as a collection of parts that can be sold as a whole gun, which meets the company's QA standards for that model. For my purposes, that is mated to the action.

Where the barrels can vary widely, as is suggested by many of the posts here, a change to another barrel may not reveal the issue because of the inherent variability in manufacture. For now, I have not received any explanations which can tell me why the gun is no longer able to group pellets. There have been many suggestions but not all of them have considered all of the circumstances which were posted. We are not talking about a millimetre or two away from the expected point of impact.

The behaviour I wish to have explained is this: I can hold the gun on a sandbag and point at the target centre through a reasonable scope, that was exchanged for two others without making any difference. I don't shoot drunk or drugged. The cross hairs of the sight are on the dead centre of the target and the pellet may land within a few millimetres of the centre of the cross hairs. The next pellet may land 2 inches below that one and be at the extreme edge of the target. I was used to having every shot land where I pointed the gun.

It may be that the pellet goes right, up, down or left. The following pellet will also hit the target randomly. The gun is not moved and the scope cross hairs are not positioned differently. Ten shots in ten different places is not about the large group made by covering 6.5 inches of the target face. There is no group at all. The gun has not been abused, nor dropped. The scope is not at fault.

The gun appears to have no damage to the bore or crown of the barrel and all of the working parts work without giving any hint of obstruction or damage. The magazines appear to feed the pellets cleanly and on axis. To all intents and purposes, the gun appears to be working correctly except in the single respect that the pellet point of impact cannot be adequately guided or predicted.

My knowledge is insufficient to draw any adequate conclusions from what has been said here and from the gun's behaviour and my limited inspection of it. If you tell me what faults a barrel can develop just by being used as intended, then I am reasonably sure that I could devise a test to reveal that developing fault.