Weihrauch HW100 T has become completely inaccurate

[Shed tuner]

is it a mag problem ? have you tried a different mag ? Has the batch of pellets you are using changed (not likely to cause such a big degradation, I concede)

If the FPS is consistent (sounds like it is), and the moderator is removed (good idea for testing), all that's left is the barrel itself, it's mountings (fore and aft), the pellets, or the mechanism by which pellets are fed into it.

[jepho]

is it a mag problem ? have you tried a different mag ? Has the batch of pellets you are using changed (not likely to cause such a big degradation, I concede)

If the FPS is consistent (sounds like it is), and the moderator is removed (good idea for testing), all that's left is the barrel itself, it's mountings (fore and aft), the pellets, or the mechanism by which pellets are fed into it.

Thanks for the thoughts. No, definitely not related to the magazines. All are genuine Weihrauch ones and seem to be working correctly and feeding well.I have tried several pellets, From Rifle and Pistol weight match grade R10s, which are my own favourite pellets. RWS Super Fields, JSB exacts, Bisley Practice, Bisley Magnums, H&N FTTs and so on. They all give the same random results.

My chrono does not show up any glaring errors for energy or fps. Had another look at the barrel this afternoon, both inside and out, and at the rifle mounting points. Removed the cylinder and checked every visible seal and mating surface. Everything looked to be in the expected order. Re charging the cylinder was easy and I did it very slowly to try and detect anything untoward or leaking as it reached its working pressure.

The grub screw holding the barrel appeared to be utterly secure. there was no lateral movement or axial end float in the barrel when mounted. The crown looked untouched. The bore looked untouched by anything sinister. The visible working parts after the stock was removed looked to be working correctly. The magazines indexed correctly. At one point I thought that the barrel was laying somewhat loosely in the stock very slightly, noticeable by a very slight rattle when the gun was moved laterally. The two securing screws were nipped up a little tighter and the rattle was gone but the random POI remained.

I tried to see if the gun would behave any differently with a different telescopic sight fitted. It made no difference to the POi. The expected POI was not what was actually achieved in test firing 70 plus pellets. Nothing really helped the gun to show the groups that it was capable of for the last 18 months. I am at a loss to know what to do next.

[Squintykid]

if accuracy improved slightly after cleaning...take the barrel off and blow it through with aerosol brake cleaner to remove any sign of grease or oil.

Double check the probe, breech o-ring, pellet seating depth, breech face and port for interference or a burr.
seat a pellet push it up to the port, push it back and look for any irregularities or shaving . Rod one all the way through past the choke to see if the problem is that end.

A sudden loss of accuracy but not power/consistency like Shedtuner has already mentioned would imply barrel or loading system.

[jepho]

A sudden loss of accuracy but not power/consistency like Shedtuner has already mentioned would imply barrel or loading system.

Having done all of the things suggested on this forum; I will take the gun back to the gunsmith today. I am of the opinion (possibly wrongly) that when a person cannot do a thing the first time around, it demonstrates an inability to do it all. He may have been having an off day so I will give him the benefit of the doubt. (the worrying quotation often attributed to Einstein springs to mind... i.e. to keep doing the same thing and expect different results is insanity). I wont be paying any huge bills though. Failing which... I need to find a gunsmith who does understand what is required and can do more than just talk a good repair.

[gingernut]

I’m with Murphy on your pellet choice.

R10 are match pellets for short range low power target work.
They come in rifle and pistol variants.
They will also probably be a bit loose in your barrel.
Superfields are not great either.

Try Air Arms Diablo Field in 4.52.
Or H&N ftt.

After you have cleaned your barrel the gun will take quite a few shots to settle down with any pellet.
As it does when you change pellet.

[jepho]

I’m with Murphy on your pellet choice.

R10 are match pellets for short range low power target work.
They come in rifle and pistol variants.
They will also probably be a bit loose in your barrel.
Superfields are not great either.

Try Air Arms Diablo Field in 4.52.
Or H&N ftt.

After you have cleaned your barrel the gun will take quite a few shots to settle down with any pellet.
As it does when you change pellet.

I have had outstanding results with R10s. Pellet on Pellet at 25 yards. They make a range of sizes and 4.52 was as close fitting as I could use in my gun.

The H&N FTTs were also excellent and I used these when I first bought the gun and periodically since. Look at the images I have linked below. The 25 yard group of 5 shots, pellet on pellet, tells me that I must be doing something right. The subsequent scattergun targets with the appended text show me that something is amiss with the gun, rather than the pellets, of which I have tried several very well known makes, as I had listed previously.

I cannot understand why people are trash talking RWS R10s other than their own prejudices. I have found them to be a fantastic pellet for removing yet one more variable. In one 500 pellet tin for my pistol, I found one pellet which did not weigh 7.0gr. it was 7.1gr. That tells me something about the care taken in the manufacturing process and the subsequent quality assurance processes of RWS.

Of course, your own mileage may very well vary from mine but... forgetting your own experiences with pellets and guns for a moment - My experience with the pellets mentioned has been nothing but fantastically accurate. It now is not the case and for no obvious reason. I am trying to find out what that reason is because it is clearly something which has changed in the gun. This rifle has been used every week for 18 months without missing a beat.

Please excuse me for saying that the pellets I have chosen to use; appear (to my mind) to have absolutely nothing to do with the change in performance that has taken place in a gun which has demonstrated near match accuracy. I would score in the high 230s on a target face of 11mm at 25 yards from a sandbag and a score of 70% hit rate on a bench-rest target of 6mm at 25 yards while using a sandbag.

Look at the well grouped shots on linked target face one and then the rest. I see no engineering rationale for the previously successful pellets producing such wild variations. I am more than willing to learn and would be delighted to fill the numerous gaps in my engineering and shooting knowledge. I will of course be happy to try something that I have not already tried. thank you for your suggestions.

https://www.dropbox.com/sh/hxyps7ma7...th61b3PDa?dl=0

[old goat]

Like yourself had the same problem with my previously accurate HW100 went through the list of barrel cleaning and all the checks you have tried without any improvement, about to give up when a club member suggested I try a different batch of the JSB Exacts I had been using,problem solved,the Exacts i had been using differed vastly in size and length from my previous batches,i have always found my HW100 barrel to be pellet fussy

[gingernut]

I’m not trashing R10s.
I use them in my match pistols and rifle.
At 10 yards.

At 25 yds a bit of wind will send them all over the place.

[zephyr]

Hello Jeff,

I too would be flummoxed after having gone through the checks you have.

Are you still using the same tin of R10s? or a different tin?
Has the grouping also suffered with the other pellets you said you had previously been happy with?
As unpalatable as it may be, is there anything the shooter is doing that introduced the expansion of the groups?

Clearly something has changed from when you were able to get the fantastic group. You quoted Einstein (with which I totally agree), so to quote someone else "Once you eliminate the impossible, whatever remains, no matter how improbable, must be the truth.". You now have to think of the improbables, which will include everything not just the mechanics of the gun. The checklist will be vast, good luck.

ps different guns for different people - I sold my HW100 and kept my Mk4is.

[NewPaul]

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[rapidave]

hello jepho i had a similar problem with my .20 hw100 t but that was because i had adjusted the regulator to high. so after a lot of adjustment with the hammer plus regulator turned down the pellets were not spreading but grouping very tight, have you your self adjusted your reg at all. hope this is of some help to you.

[jepho]

Like yourself had the same problem with my previously accurate HW100 went through the list of barrel cleaning and all the checks you have tried without any improvement, about to give up when a club member suggested I try a different batch of the JSB Exacts I had been using,problem solved,the Exacts i had been using differed vastly in size and length from my previous batches,i have always found my HW100 barrel to be pellet fussy

Thank you for your time and the valuable response. In engineering terms, I don't understand pellet fussy as a description. If that means that Weihrauch makes a barrel that is set to handle different pellet configurations in different ways, then the parameters used to manufacture the barrel are known and the best pellet for that specific configuration of the barrel is also a known. Knowing how German engineering tends to handles issues, I would expect Weihrauch to understand barrel variation and the implications of each standard deviation barrel from the expected norm.

Hitherto, all of my pellet choices have demonstrated and underlined the accuracy of the HW100... so much so that my son called it "cheating", every time I used the gun; regardless of the pellets I used. For now, I have left the gun with a highly recommended gunsmith and will report back to the thread once I know what the problem is and how it was solved. As a scientist and an engineer, I want to learn about the explanations that make sense to me. Feelings and beliefs have no place in my world and all things are explicable.

Since the problem began, I have used just about every high quality pellet available and still I am not seeing any improvement. This fact alone suggests that pellet choice is not responsible for creating the problem. For the sake of furthering the debate, if we accept the assumption that all pellets are different, then I should have seen an improvement representing consistency, even if the group was orange sized when I changed my pellets. No such improvement in consistency has been seen. All pellets produce the shotgun patterns shown.

[jepho]

I’m not trashing R10s.
I use them in my match pistols and rifle.
At 10 yards.

At 25 yds a bit of wind will send them all over the place.

Thank you. My mistake and I am sorry you got caught up in what I saw as another complaint against a perfectly usable pellet. 🤭
FWIW, all of my recent shooting has been done indoors so I don't have the wind to contend with. I am currently waiting for the completion of a 70 yard outdoor range.

[jepho]

Hello Jeff,

I too would be flummoxed after having gone through the checks you have.

Are you still using the same tin of R10s? or a different tin?
Has the grouping also suffered with the other pellets you said you had previously been happy with?
As unpalatable as it may be, is there anything the shooter is doing that introduced the expansion of the groups?

Clearly something has changed from when you were able to get the fantastic group. You quoted Einstein (with which I totally agree), so to quote someone else "Once you eliminate the impossible, whatever remains, no matter how improbable, must be the truth.". You now have to think of the improbables, which will include everything not just the mechanics of the gun. The checklist will be vast, good luck.

ps different guns for different people - I sold my HW100 and kept my Mk4is.

Hi zephyr. 👋🏻
Thank you for your thoughts and your helpful input.

I have taken pellets from 7 different tins of R10s. I have added JSB exacts, Bisley Magnums, Bisley Practice, H&N FTTs and RWS Super Fields. The random scattering of shots has occurred with every pellet from every tin.

I am not drunk or drugged when shooting every week. I can and have shot freehand, standing and sitting plus I have used a sandbag and a bench-rest and the results are similar across all modes of shooting and all pellets. I don't believe that my technique has changed and suddenly become inaccurate. At the weekend , I shot a group of five from 16metres. The group was less than the size of a small fingernail and it was produced with a fairly old Walther LGR. At 25 yards, I shot a group about the size of a 5p piece with open sights and an HW77.

Hopefully my leaving the gun with an expert gunsmith will throw some light on the issue. More anon once I know what has changed.

[jepho]

hello jepho i had a similar problem with my .20 hw100 t but that was because i had adjusted the regulator to high. so after a lot of adjustment with the hammer plus regulator turned down the pellets were not spreading but grouping very tight, have you your self adjusted your reg at all. hope this is of some help to you.

Hello rapidave. Thanks for the thought. I have never adjusted any aspect of the gun since I first bought it. If the problem can be solved by adjusting the hammer and the regulator, I am sure my gunsmith will do it. I know just enough to know when I don't. In this particular case I don't know enough to make an effective attempt at adjusting whatever requires twiddling and fettling.