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Air Gun Forums » Air gun Alley » Turkish blend » My VMX .20 cal got a Hatsan gas ram...

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Old 07-15-2017, 12:57 AM   #1
SteveP
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Default My VMX .20 cal got a Hatsan gas ram...

I've had an itch to try this since seeing they sold the VMX rifles in the UK with what they called a D-Ram gas piston so during the last sale at Field Supply, I grabbed a Hatsan 1000X Vortex .25 to try it.
The rifles aren't quiteee the same but the difference is inside. I tore both apart and gotthe VMX tuned: deburred everything, honed, polished and finding a flat edge on the piston seal, replaced it with a brand new Vortek piston seal which at least in my case, popped right on with simply setting it on the bench, angling one side of the piston into it and pressing forward and down to seat it. It also fit very nicely into the newly honed cylinder and the rifle went back together with no hitches or glitches.
At least until I tried cocking it....at which point it wouldn't. The piston wouldn't go back far enough for the sear to lock and at that point after 40 hours with no sleep, I set it aside and sent a friend who'd done his own version of a swap a pm asking about his and after reading his reply, I went back and tore it down and found what he figured I might.
There is a difference between the older and newer rifles and it's in the piston. In the pic of the pistons below, the top black one is the new Hatsan piston and the lower silver one is the VMX. The width of the slot the red arrow is pointing at is the difference in the length of them. There's also no hole drilled inside the piston for the end of the gas ram arm, so between that and the extra length of the piston, it was causing the rifle not to cock.
It wasn't quite as simple as just dropping in the Hatsan gas ram, you'll also have to use the Hatsan piston, but the rifle is back together and shoots very nicely. Smooth cocking and shot cycle, no real difference in recoil and because I also took JSB's and FTT's outside with the chrony, it also has more power.
-JSB 13.73gr:
-With spring: Average 715, ES 10, SD 2, FPE 15.59
-With Gas ram: Average 756, ES 27, SD 8, FPE 17.43

FTT 11.42gr:
-With spring: Average 773, ES 19, SD 5, FPE 15.16
-With Gas ram: Average 812, ES 25, SD 7, FPE 16.72

The ram already had something like 100 shots on it before I installed it so I'll be shooting it more to settle it into the VMX at which point I'll chrony it again in 500 shots or so and see if there's any difference, but i'm happy with the swap. Plus, I kinda borrowed/stole Nick's idea and bought a 3rd one that got delivered 2 days ago so the first one I bought will stay bone stock the way it came out of the box (shoots excellent btw), the second now gas rammed one and the third will at some point get a full tune.
Only thing I now have left to do is take the spring setup from the VMX and put the 1000X back together as a springer so I can see the difference between it being gas rammed and a springer.
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My favorites: Hatsan Galatian III QE .25, Weihrauch HW95 .22, Beeman R9 .20, Webley Tomahawks in .177 and (2) .22's and a few (21 for now) others

Last edited by SteveP; 07-15-2017 at 01:00 AM..
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