Hatsan Mod 95 Custom Ram Conversion Machine Parts

[gene_sc]

Here is the procedure I used to custom fit a Crosman NP Gas Ram into a Hatsan Mod 96. First I take measurements of stroke length of piston when fully cocked to determine if this would wok. I have done enough of them now that just by looking at the parts and stoke lengths I have a pretty good idea a no or no go..
 
The Mod 95 I knew would take a NP ram as soon as I broke her down. Originally I was just going to use the spring and give her a nice turbo tune with custom fit JM seal and lube. But since I own a Winchester 850 XS now that is the exact same powerplant that I tuned using the original spring and custom seal I decided to just make the Mod 95 a Gas Ram.
 
Custom part to make this work are generally per model and not just generic. To do it right you have to have a certain amount of preload on Gas Ram plus till have enough room for trigger block. Sometimes it can be very close like within thousandths. Remember the stroke has to be full length of ram and no less and still have piston engage the seer properly on the trigger. This can be a safety issue which really makes or breaks a close call.
 
Below are the part or parts that make up the conversion. This particular job was very basic and easy. NOTE: One thing that really tipped me off about the conversion was when I was cleaning the inside of piston and following up with a light to shine down inside piston to see if there were any visible dirt or chips was I spotted the key to the project.. Hatsan has made the new style pistons with a recessed hole at front inside of piston to facilitate a Gas Ram shaft centered.. This tole me that Hatsan has some future ideas in the oven...
 
I also might add that I cocked up the piston in the mill and cleaned up the cocking slot. As well as using a JM seal that I custom sized to fit bore of combustion chamber.
 
The gap on the nipple end of piston where seal sits has to be opened up approximately 0.30 so JM seal will seat in slot. I did this process on the lathe with cutoff tool. If you do not do this step your seal will not work on the piston.
 
 
 
 

[Smackey54]

Looks pretty slick, Gene! Is that collar at the rear of the NP to maintain the piston centered?
Man! You got some nice toys to work on those with! I am GREEN with envy!

[Toolmaker]

Nice work Mr. Gene!

[gene_sc]

Yes Mark you can see that I drilled bored the piece in the lathe. Hole for nipple on front of trigger block plus larger hole for piston end to sit in. It also has to have flat spot on top so it willnot interfere with the trigger seer. Worked out just great and the cocking and shooting cylcle was like glass.

[GarthThomas]

Did you have the option of facing the piston either direction if you wanted, and do you think the weight of the piston cylinder moving forward would cause too much stress on the other components. Would putting a gas spring likely lesson the chance recoil damage to scopes.

[gene_sc]

IMO and basic mechanical common sense I would not reverse direction of ram. Why?, because you risk damaging the internal parts of the gas ram. Remember that is where the gas is stored and pressurized. With the Ram body facing to front of gun it takes all the impact.

Did you have the option of facing the piston either direction if you wanted, and do you think the weight of the piston cylinder moving forward would cause too much stress on the other components. Would putting a gas spring likely lesson the chance recoil damage to scopes.

[Scotchmo]

gene_sc,
I also thought that the gas spring body should be in the back of the rifle but have since changed my mind. I now mount it in the direction that is the most convenient and/or performs the best. No problems with the reversed gas springs yet. Theoban was an early adopter of gas springs and they also sold a variety of conversion kits for different rifles. Many of those kits had the gas spring reversed.