Tuning Dr. Bob's bottle conversion on hw100

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MEC17670

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May 8, 2015
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Prunedale,California, United States
Hey Guys,

Just curious if anyone out there has tried the Dr. Bob's bottle conversion kit?

I put one on my gun which I found to work great. Increased shot count at a higher ftlbs.

I do have 1 problem as it drops about 100 bar overnight. Didn't at first, but after pulling on a sling mount bracket mounted on the bottle. It started. I thought that the sling might have turn the bottle some causing the oring to stop sealing. Tird rotating the bottle abit but no go.

Not a deal killer, as it will last for the days hunt, just an itch. 

Any thoughts?
 
Here's the finished product. The major thing is when you chop the stock is now you are taking away the linear support of the action in the stock due to the lack of the oring air vessel/ barrel support in the fore stock. Alignment of the action/stock screw must be done very carefully.

During non-pesting season , I'm planning on attaching a wooden under forestock to put upward pressure on the bottle, thus aligning the action better. But for now it works fine.

The bottle is a Fx 480 ci carbon fiber bottle, with a fill of 3600 psi.

My HW100 has a FX smooth twist barrel, AZ tuned with a custom moderator. Extremely quiet. Regulator set at 140 bar allows me 75 shots at 33ftlbs. 18.1 gr. Pellet at between 870 to 875 fps. With the FX .22 gr. hybrid slugs I'm getting 820fps. I have to move my elevation know on my scope 10 clicks up for zero. Windage remains the same. The slugs really smack. I've tried others but these slugs seem to provide the best accuacy.

The

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One thing more for the interested parties should know , which would be a great opportunity for those machinist, is the male end of the DBC unit , where the bottle screws into the unit does not allow for bottle valve on the fx bottle to be screwed into the unit. I had to remove the valve for the bottle be able to be screwed into the unit.

Here's the catch, the oring on the bottle that seals the bottle to the unit run when seated will run across the main unit hex headed screw joint that is used to install the unit to the gun. Seems flakey. 

If some interest machinist would make a female sleeve that would match the male end of the unit oring , then extend with a slightly larger based male end that would then screw into the bottle allowing for the bottle oring the seal correctly against a solid groove. This would eliminate the slow air leak from around the bottle in the original configuration. 

Food for thought. Any ideas?
 
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I'm sure the bottle conversion serves its purpose, but man, it really ruins the classic appearance of the rifle. Obviously, that's a subjective observation, and just my opinion. It's a great rifle, so expanding its usefulness is a good thing for those who want it. Like a lot of European rifles, I assume the HW100 was designed around a 12 fpe platform, so big power and high shot count, relative to the market today, may disappoint some owners. Mine is a back yard and short range pesting/plinking rifle, and for that, it's perfect as is, even in the smaller capacity carbine version. 
 
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I totally agree with you. 

The main market for the Hw100 is the sub 12 ftlb market in the UK. The Hw100 is a very classy airgun with beautiful lines, super smooth action, and at a sub 12 ftlb level provides everything needed for the hunters in the UK , a fantastic tool.

I am surprise that Hw hasn't developed a rifle for the U.S. FAC market. Hint, hint!

It was a very hard decision to make but having already installing a smooth twist barrel, I chose to go forward with the modification.

I needed to have a refresh tune put into the rifle so I sent it to AZ and let him know what I was planning to do and to tune it at a higher ftlb tune, which he did a wonderful job.

The reality of my decision became very clear to me as I started chopping the stock to fit the action into the stock, but with a vision of my end goal, I painstakingly proceeded slowly cutting the stock down, taking small pieces at a time . 

Having reached the point where the action would fit , I put air into the air vessel and gave her a go. I wasn't disappointed, more power, higher shot count, and maintained the rifles pin-point accuracy. 

No regrets. First outing , I killed 56 ground squirrels out to 76 yards without having to refill the air vessel. 

This rifle is a work in progress, next step is adding a forestock to support the bottle and action better. 

It is my hope that Hw sees the market for adjustable power leveled airguns and put thier engineering talents and manufacturing skills to the next level.

Thank you your input.


 
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