Got a new 98 to day and can't keep it on an 8x11 sheet of paper at 22 yards. Had to tighten the stock screws. Put a proven scope on it. Pellets made no difference. Even remounted the scope just to make sure. Had just taken the scope off of HW97K that was shooting great.
It's very-early in the trial stages, but the tip about cleaning the barrel is a great one. Lots of rifles make the trip overseas with heavy grease in the bore to prevent rust. Once that job's been done, you need to get it out of there. Clean the barrel, shoot 15 pellets to re-season the barrel with lead, and retest.
You should make sure the pivot bolt tension is adjusted correctly, and add just a dab of heavy oil or grease on the detent plunger.
The pivot bolt tension is adjusted correctly when, after the rifle is cocked, the barrel stays put at the location wherever you put it, but not so tight that it binds in the receiver forks. If you give the barrel a slight push, it should move just a couple of inches and stop. If it moves further than that, like if it's 'floppy', it's too loose for maximum accuracy.
And, you didn't seem to mention anything about having a chronograph. Do you have one to use? If so, check the velocity with the pellets you're using to make sure it's consistent. Without one, you can place a tissue over the breech block seam to see if the tissue moves when you shoot a pellet. Weihrauch is pretty good about not having a leak at the breech, but it's still possible.
You said "pellets make no difference". Does that mean you tried 2 different brands, or you tried 6 different brands? Keep in mind that just because the brands you have work for other people who have an HW 98, it doesn't mean they'll work for you.
Make sure the rifle is un-cocked and unloaded, and inspect the barrel crown under magnification and a good light to make sure it looks smooth and even.
There's a fairly-comprehensive tutorial about what can be wrong when a new springer when it won't group. It's about all that I can think of from here and not have to type my fingers to the point of fatigue :). If I was there we could probably figure it out in 30 minutes, assuming we had a chronograph to use. HTH. Let us know.
When you say the hinge was very-tight, I'm not sure if you're saying you mean you think that's OK or not. TOO-tight isn't good, and oiling it alone won't solve the problem.
The correct way to take care of a pivot bolt that's very-tight is to 1. Loosen the lock nut on the shooter's right side of the barrel, 2. Loosen the bolt by its head on the shooter's left side of the barrel, then 3. Re-tighten the lock nut so the bolt stays put. Even when you do it that way, re-tightening the nut on the Weihrauch rifles has the tendency to cause the bolt to re-tighten just a little. You have to test the setting of the bolt at the very-final setting of the lock nut to see if it's just right or not.
With that done, it sounds like you will have covered a few of the most key issues. At that point, it may not be a DIY fix. You may have to get someone with more experience to look at it for you (like maybe the dealer who sold you the rifle?). I'm certainly in agreement with you that the 'accuracy' you're getting out of it is most-unusual and totally-unacceptable. But, I'm sure it can be rectified one way or another.
plain and simply it should be in the mail back to the seller and a new one sent, if you buy a new gun you should not have to post on any forum to figure out what is wrong but to say look at my new rifle or pistol and tell everyone how great it is
new guns don't need to be fixed they need to be shot
It's the gun not the barrel. The hinge was very tight when I got it. It has loosened only slightly with use. I shot it again to day and it shot about 1 inch horizontal and 6 inches verticle. 5 inches between consecutive shots
A barrel cocking rifle with a hinge that's too-tight will produce vertical stringing, even if you oil the hinge and oil the detent. As someone who's tuned and/or repaired close to a couple of hundred spring piston air rifles, I can tell you that I've seen it for a fact, and more than once. It may be all of your problem.
I know I could be wrong, because I haven't inspected your rifle in-person. And, this whole discussion of what's "tight" or not is really kind of subjective, isn't it? It's not like you measured the cocking effort with a scale to compare with the cocking effort of other HW98's (or at least you didn't mention it). It might be close to being acceptable like it is, and the problem lie elsewhere. But, it would be very quick and easy to adjust the hinge for a lighter hinge setting, and retest. You could try it if you want to--you could be literally 15 minutes away from resolving your problem. Take it for what it's worth. It's your gun, and I've certainly been wrong before.
If you're dealer is replacing it, I suppose that's the best fix of all, with all of your bases covered. Hopefully they'll test the accuracy of the replacement they're sending you before they give it to the carrier, and thus they will have verified that it's shooting like it's supposed to. I hope you wind up with a good air rifle.
I think that most of us like to be able to fix what is wrong with thing, anything, maybe it less of a hassle
but it is a big mistake, if the rifle, pistol or anything else, send it back, take it back, this scratching your head trying to fix it is just nonsense
you bought something new and it should be right, bottom line, you can wait for a new one it just doesn't matter, but what does matter is receive first class top notch merchandise not some second rate crap
how many of us have had a problem with something new and had a problem and after a while got it to work right but after screwing with it for X amount of time you hated the damn thing, you kept it but hated it at the same time
if it is not right send it back
rant is over
It's being replaced. I have had a lot of air rifles so familiar with them. The hinge was so tight that it was hard to close the barrel. I loosened it and didn't know how much to tighten it back. It started shooting vertical 6 inches, about 1 inch horizontal. Getting a new one.
Thanks for all the help