Bad accuracy

[SSMOOTHY]

Hello airgunners!

I recently bought the Hatsan AT44 .22 (single shot) as my first venture into the dark side, along with a Hawke Panorama (4-12x40 AO).
Right after having received the thing i chronied it and did the "3 valve hole plug mod", with great results as far as the speed/shotstring goes.
Then i tested for accuracy using JSB Heavy (18.1gr) and JSB Exact (15.9gr), and both made me cry..
I have only tested at about 15 yards distance, on a steady bean bag, but the pellets just seems to hit about half an inch left, right, up or down, whichever they seem to feel like.
Then sometimes, it will put 10-15 pellets in the same hole (at random pressures), and 10 minutes later it will be bad again with occasional 1 inch+ flyers.

I so far have tried pushing a pellet through the barrel; doesn't look bad. The crown doesn't look way off (to me). The inside of the barrel seems ok.
I have also tried removing both barrel bands, removing one barrel band, removing the o-ring in the barrel band, put just one barrel band at the barrel-end. No improvement.
I do have a weihrauch moderator fitted, which i basically can't shoot without in this neighborhood, but i tried removing it just to test, and while the occasional flyers seemed to disappear, after adjusting the scope, the whole grouping barely improved.

I'm really at a loss here. Especially the occasional random 1-hole accuracy has me puzzled. Sending the gun back is sadly no option.
I came to pcp thinking accuracy would be great, but this is just sad.
Is there anything i should try before i give up? Could a different pellet make that much of a difference? Could it be the brand new scope?

I hope someone can help me out here.

[BenjiHunter]

Take a q-tip in the muzzle and see if you have burrs in the bore.
If it gets stuck, you have to clean the bore from burrs.

[amb5500c]

YES, pellet types, weights, shapes, brands, head diameters, etc. can make ALL of the difference. Until you've tried every pellet out there, you'll not know for sure which one is best for your gun. Most folks experiment until they find ones that work satisfactorily. Hopefully without having to try too many, to keep costs down. But, the moderator on your gun could be part, if not all of your problem. It could be that its not centered perfectly and the pellets are clipping it on the way out. It may have to be drilled enough for clearance, or tweaked some other way.
Richard

[Dog-gone]

Sounds just like a scope to me. Can you take it off and try the iron sights to be sure ?
Good luck.

[SSMOOTHY]

Thanks for the replies.
I have just taken the barrel out, checked for any burrs or irregularities but all looked ok.
Did push a few pellets all the way through it, and while the rifling marks looked very crisp and clean, it was very noticeably harder to push right behind the transfer port (where the rifling starts) and again where i presume the choke is at the end of the barrel. The transfer port itself doesn't seem to catch on the pellet.
Could a pellet with a slightly smaller head size be the solution?

(I guess i'm just finding it hard to grasp that the JSB Heavies aren't accurate in this gun since i've only read from people saying they work great in theirs.)

@Dog-gone; i did try the iron sights, but aiming at the exact same spot from anything more than 5 yards away is too difficult for me to determine if it's me or the gun.
I also did clamp the gun in a pretty stable work bench/vise, and there was still too much spread, but i'm sure this isn't 100% foolproof.

I knew this gun needed some tweaking to shoot accurate, but when everything i try fails, and i can't seem to figure out what is causing this, it's slowly but surely starting to drive me nuts 

[Dog-gone]

What you are trying to do can be extremely frustrating no doubt. It sounds like you have spent a lot of time going through the rifle. I mentioned the scope because your description of the problem stated that at times you get one ragged hole and then they start jumping around. This description that you explained is exactly the same problem I recently had and the problem was the scope. Im not saying that your problem is the same for sure but the description of the problem sure does match the problem I had. If its still jumping around with open sights then youve eliminated the scope as you already know. Im sorry that I cant further assist you with what would be the next logical step for troubleshooting or a good process of elimination. For heaven sakes surely we will get you headed on the right track before you give up on it. Its none of my business and you are in no way obligated to answer but Im curious why you said that sending the gun back is not an option ?
Either way the best of luck.

[Bwalton]

YES, pellet types, weights, shapes, brands, head diameters, etc. can make ALL of the difference. Until you've tried every pellet out there, you'll not know for sure which one is best for your gun. Most folks experiment until they find ones that work satisfactorily. Hopefully without having to try too many, to keep costs down. But, the moderator on your gun could be part, if not all of your problem. It could be that its not centered perfectly and the pellets are clipping it on the way out. It may have to be drilled enough for clearance, or tweaked some other way.
Richard

I have to totally agree with Rich, In my guns I have tried over 10 different pellets before arriving at the right one. JSB are known also for their deformed skirts. If it is a new gun you have to let it settle in a bit, check for loose things like screws, and scope mount. You have to do a process of elimination, check for loose things and tighten them, then  hand pick 50 good pellets. Then do 5 groups of 10 shots. Adjust the scope as needed, but remember when adjusting the scope you need to take a few shots to let it settle down also.

[SSMOOTHY]

Thanks again guys!
@Dog-gone; i agree that it still could be a scope problem. I just wish i had another scope around to test the gun, or another gun with good accuracy to test the scope ofcourse. Sadly i don't, so i'll have to come up with some other way of doing it.
I'm thinking of just bringing the scope back to the dealer i bought it from, and saying i highly suspect the scope has issues.
(I know they have a shooting range in the basement where they zero their customer's firearms, so i'm sure they could test a scope as well.)
But i've found out they're not very willing to spend time on their "airgun customers" unless they can make money doing it.
The problem with sending the gun back is that i have taken the gamble to order the gun abroad, for nearly half the price they are selling them in my country, but with a chance of never actually receiving it or getting it in a couple more pieces than you were expecting.
Luckily i did receive it after a long wait, but sending it back for replacement is certainly pushing my luck too much.
But i do however highly appreciate your input, no matter if it happens to solve my particular problem or not, so thanks again!

@Bwalton; I guess i really should just stock up on different pellets then, and see if there's any that can turn this sprinkler into a tack driver.
My local gunshop doesn't have that great of a diversity in pellet choices, especially not in .22, but are there any particular brands you could advise?
I'm guessing i should just skip the cheap pellets and go for the trusted ones? (Already tried some cheap Gamo's but quality was horrible on every pellet in the tin.)


I did buy the cheapest mounts they had available, the NCstar RB25, but only because they seem to get good reviews.
Could this possibly be the problem? I'm in no way knocking the scope or mounts in between shots...

[SSMOOTHY]

Just to rule out the obvious i took some pictures of the crown and pellets after having been pushed through the barrel.

[SSMOOTHY]

Managed to try out a different scope today, and i've pretty much ruled out a scope issue. Bad accuracy still 

[Voltar1]

Redo that crown, smooth breech leade concentric to bore, Aerosol and GooGone the bore
Repeat tests.

[Bwalton]

Managed to try out a different scope today, and i've pretty much ruled out a scope issue. Bad accuracy still 

Process of elimination good keep going...

[AudiS4]

Managed to try out a different scope today, and i've pretty much ruled out a scope issue. Bad accuracy still 

You should let a friend that can shoot, test your gun.

[mobilehomer]

That crown is terrible. The chamfer should be sharp and well defined. This one is way too deep.  There are several good crowning videos on YouTube. Take your time and have fun.

[nappyman]

I agree, the crown looks like Steve wonder worked on it