HW90 help needed

If you have not already check it over a chrony and make sure fps is stabile, then get to testing different pellets, check the muzzle crown, breech seal, pivot bolt and other usual suspects...

Dave Slade at airgunwerks can also take a look at it and see if the pressure if off or what else might be happening. http://airgunwerks.com

If you have not already check it over a chrony and make sure fps is stabile, then get to testing different pellets, check the muzzle crown, breech seal, pivot bolt and other usual suspects...

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Bingo!

napairgunner Dave is probably in U.S.,I'm in Canada. Thanks Crow

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Yes he's in TN but he knows those rifles better than anyone so good to ask him any questions if you can't get them answered here. 

Dude before you go wasting money, not actually wasting it with David but unnecessary spending I should say, go through things that you can do for yourself now. Like put a tissue over the breach area and shoot see if it blows that will indicate a French seal problem I believe. Then there's proper tensioning on the barrel pivot. It might be too tight it might be too loose. Then there's the crown you can check. And just like Mike says you should chronograph it. And along with that would be different pellets. How does it shoot with open sights at 50 yards or 25 yards?

These rifles have a pressurised piston that can be pressurised or depressurised. Out of the box, that piston is very highly pressurised and I found the same accuracy issue with my .22. I test fired some pellets into a drum of water. 

You must do that yourself because my English is limited and I cannot properly describe what I saw. The pellets came out as a straight sided tube!

The piston creates so much pressure inside the rifle that they blow out the sides of the pellet and it exits the barrel in the form af a tube. Therefore there is zero accuracy.

I got the pump kit and reduced the pressure by about 25 % and then it started shooting better.

The quality of the pellets also play a role. Cheaper, thin-walled pellets dont hold up, but the better quality pellets with thicker walls like the JSB's '15 and 18 grains are doing well.

Just my 2 cents.

I absolutely love these adjustable Theoben and Beeman/HW/Theoben guns!

Many will tell you these guns are built for 20 FPE and should be shot at that level. I have found that by adjusting the pressure you also affect the shot cycle timing. Small changes can have a profound effect. In .177 right around 12 FPE produced the best accuracy, around mid 13 FPE for the .20. You may have a hunting case where you would be willing to trade some small amount of accuracy for power or an FT case where you are limited to a certain FPE. But in terms of chasing accuracy only, this has worked out well for me. 

This of course assumes you have ruled out the crown and soft part concerns. 

BTW have you tried a really good barrel cleaning? If you do, please understand it may need to lead in again a bit before the best results are found.

Your mileage may vary.

My 27+fpe Eliminator, 3 Kodiak's 27-30fpe and two 32-36fpe Dual Magnums have NEVER distorted a pellet in such a manner as you describe UNLESS firing into water. It's the water that will distort most pellets from many guns!

Cocking effort is almost always relative to power output but can be lessened or increased pending barrel/lever length.

Thanks for posting this Crowski. Was about to pick up an hw90 myself, in .20 ...now am on the fence following this thread...some popcorn in had to see what the findings are; ultimately if worth the purchase. Thanks again, all also.

Sounds like if one were to pick up an hw90, best to pick up the gauge and pump so you can adjust the pressure accordingly(?)

I have one of these and had the exact same problem. I found that it was difficult to cock, the firing behavior was unpleasant and loud, and accuracy was nonexistent. You may notice that the ram is pressurized to 26 bar. I bought a rock shox pump and a number of fittings to create an interface between the pump and the rifle, all of which are outlined in an easily found post on GTA, and then adjusted the pressure to 22 bar.

The results were immediate and gratifying.

The rifle, once unpleasant as hell to shoot, is now one that I can count on to perform very well. It is accurate and recoils in a mild and pleasing manner. Also, it is much easier to cock, and the loud bark is notably diminished.

And if anyone doubts the effectiveness of a 20 grain pellet (H&N 19.9 Field Target Trophy) moving along at 619 fps, keep in mind that at thirty yards the pellet completely penetrated a 5/8 thick cedar fence picket and then embedded itself into the concrete mastic of a cinder block wall. It's plenty powerful enough for most small game hunting.

Do yourself a favor, lower the pressure to 22 bar. It'll transform the rifle.

The pressure guage is really not as important or even needed if a chronograph is used. Even Theoben says to go by chronograph and staying within or below the fps recommend for each particular/your gun. The PSI/BAR will never match the accuracy of a chronograph or fine tuning to a pellet of choice.

I read this with interest! I still haven’t posted a review on my hw90 in .22 because of accuracy issues- cantaloupe happy at 25 yards. However, some problems were the scope backtracking, and I’ve since got the back mount to stop sliding while front mount is keeps the actual scope from backtracking due to swell....

Anyways, I did not find any heavier pellet accurate, over 18 gns. I was told HN pellets were usually best, but in the end it was the jab 15.9’s that have done close to half an inch at times. From the bench I often feel the hw90 twist or move differently after the shot. I’ll soon be testing off my knees sitting to see if my body alone provides a more consistent motion.
looking forward to seeing what