Converting the Hammerli 850 .177 to PCP

Ongoing project,
I really like my Hammerli 850 in .177, it is low power, very accurate at 25m and it is backyard friendly. The only annoying thing is the CO2 88gr and the cooling effect. If you wait 20 seconds between shots then the speed is constant. If you shoot faster, the CO2 cools the cylinder and the pressure drops resulting in slower exit speed of the pellet and loss of vertical accuracy.
On a warm day its different than on a colder day...
HPA would solve all this problems of course.

basic idea:

• get a small aluminium paintball cylinder: 

  

  First Strike 13CI 3000PSI with hero regulator (800-900psi)

  
  
• get a conversion adaptor from 88g co2 thread to Paintball : 

  

  Best fittings 850 Air Magnum Adaptor 

• get a remote filling line for paintball 
  

2 possible solutions

solution 1

Use the remote fill and the conversion fitting.

pros:

• no need to chop up anything
• consistency of HPA
• can still use 88g co2

cons:

• the small hpa cylinder needs to be carried along.
• small hole needs to be cut, to let the remote line exit

First results:

With the standard pressure on the hero regulator of 800psi I get the same results as using CO2. The pellet speed is very constant @530 fps with 15grain H&N. Which is 9.4 Ft. Lbf or 12.7 Joule.
I'll do some more tests in the coming days with the regulator set at 900 psi.


some photos:

small hole drilled to feed the air

My new benchrest gun in .177

solution 2

Do a full permanent conversion.
the air cylinder needs to be mounted on the hammerli and holes need to be cut for the fill nipple and the gauge

pros:

• no need to carry the cylinder anymore
• consistency of HPA

cons:

• holes need to be cut into the hammerli
• no more co2 possible

I'm going to start with solution1 and if it works great,  I'll do solution2 after all my CO2 88g runs out.