Tuning HW100 T .22 - air puff upon firing

Jump to latest Follow Reply
B

bdzjlz

Member
Jul 11, 2016
2,379
2,376
Terre Haute, Indiana
I have an absolutely brand new Weihrauch HW100 T in .22 caliber that just arrived Wednesday vis UPS. While pellet testing ( it appears to be deadly accurate with about anything I feed it), I can hear and feel a little puff of air come back and hit me in the face with each shot.


Do you think I am correct to assume this is a leak at the pellet probe? Velocities seem to be about what I would expect but the shot count before it falls of the reg is only about 35 to 40 shots.

Additionally, I expected it to be super quiet with the factory moderator but it produces a significant “pop” upon report, making me believe there is an o-ring leak.

Your thoughts would be appreciated. It came from Krale so I am not sure if the service implications.
 
I have an absolutely brand new Weihrauch HW100 T in .22 caliber that just arrived Wednesday vis UPS. While pellet testing ( it appears to be deadly accurate with about anything I feed it), I can hear and feel a little puff of air come back and hit me in the face with each shot.


Do you think I am correct to assume this is a leak at the pellet probe? Velocities seem to be about what I would expect but the shot count before it falls of the reg is only about 35 to 40 shots.

Additionally, I expected it to be super quiet with the factory moderator but it produces a significant “pop” upon report, making me believe there is an o-ring leak.

Your thoughts would be appreciated. It came from Krale so I am not sure if the service implications.
Click to expand...



I’m not familiar with that rifle, but in my experience a puff of air to the face is caused by an o-ring issue or air stripper holes at the end of a shroud being close to your your cheek rest. Try replacing the breech o-ring or the o-ring on the pellet probe. If the breech isn’t sealed off properly it can cause your shots to be louder as well. This is most notable (to me) if you don’t close the breech all the way/secure the bolt and fire resulting in blowing out the breech o-ring. Hope this helps remedy your issue. Someone with more experience may provide more insight here. 
 
Upvote 0
Hi bd,

A test I use. I carefully load a pellet w/o the magazine (at the range!). Put a Kleenex or generic toilet tissue square over the breach area where the magazine goes. Safely discharge the airgun into a backstop and watch the tissue. If it blows off the breech, it is time to do some repair work. I always do it a few times to make sure. I've changed all the O-rings in my HW100. It is a little tricky getting that one in but be patient. A few simple home made tools make it pretty easy.

Enjoy the new HW100. One of my favorite airguns.

Take care,

Nugria
 
Upvote 0
I believe I have this issue fully resolved. 

Thinking back through the rifle's set-up, it seemed to me that the shroud began to spin when I installed the threaded moderator.

I removed the stock and the air cylinder assembly, and the shroud and the allen head shroud locking head screw were very loose. I took a rubber mallet and lightly tapped the shroud all of the way down, and after applying a vibratite sparingly to the set screw, locked the shroud down. I proceeded to reinstall the air cylinder and then the stock and again applied sparingly vibratite to the stock screws.

Testing the rifle, it was totally quiet, no "air puff," and the velocities went up 80 fps with the JSB 18 grain from where it was during my testing the day before.

The bad news, now I will have to repeat all of my pellet testing. The good news, an excuse for shooting another couple of hundred pellets.



DZ
 
Upvote 0
you might also check the barrel set screw, it is the one above the cylinder that is at a 30 degree angle up, snug it down, not to tight about 10 inch pounds is good, glad you found the leak, some of the common leaks are the main valve seals and the breech block seal, 

here's an exploded view of the gun, it's not the hardest gun to work on, just seems more complicated than it actually is, just remember if you have to remove the breech block, remove the barrel and when reinstalling the breech block, install the barrel last, make sure to lube all o-rings when replacing.

HW100 diagram.1644001527.gif

 
Upvote 0
the barrel butts up against the breech block, if the barrel is installed before the breech block, it will keep the breech block from completely seating, causing the O-ring to blow out, it's best to remove the barrel or you can loosen the set screw enough to allow the breech block to seat properly, I learned this from experience, I kept blowing out the breech block O-ring and realized the barrel was keeping the breech block from seating properly, good thing I had a more O-rings, LOL

by breech block I mean part # EC-215, EC-216
 
Upvote 0
I believe I have this issue fully resolved. 

Thinking back through the rifle's set-up, it seemed to me that the shroud began to spin when I installed the threaded moderator.

I removed the stock and the air cylinder assembly, and the shroud and the allen head shroud locking head screw were very loose. I took a rubber mallet and lightly tapped the shroud all of the way down, and after applying a vibratite sparingly to the set screw, locked the shroud down. I proceeded to reinstall the air cylinder and then the stock and again applied sparingly vibratite to the stock screws.

Testing the rifle, it was totally quiet, no "air puff," and the velocities went up 80 fps with the JSB 18 grain from where it was during my testing the day before.

The bad news, now I will have to repeat all of my pellet testing.  The good news, an excuse for shooting another couple of hundred pellets.



DZ
Click to expand...

Good deal. Glad you were able to track down the root cause. Thanks for sharing the problem and process. I’ve been eyeballing this gun. You now have a legitimate excuse to shoot more. 
 
Upvote 0
the barrel butts up against the breech block, if the barrel is installed before the breech block, it will keep the breech block from completely seating, causing the O-ring to blow out, it's best to remove the barrel or you can loosen the set screw enough to allow the breech block to seat properly, I learned this from experience, I kept blowing out the breech block O-ring and realized the barrel was keeping the breech block from seating properly, good thing I had a more O-rings, LOL

by breech block I mean part # EC-215, EC-216
Click to expand...

My mistake. I separated the two major modules, but did not remove that part. I did not need to access the valve.
 
Upvote 0
You must log in or register to reply here.
Top Bottom
Back
Home
Forums
Resources
Menu