GTA
Airguns by Make and Model => Hatsan Airguns => Topic started by: SteveP-52 on July 23, 2017, 04:16:46 PM
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After using the gas ram and piston from the rifle to gas ram one of my VMX .20 cals, I took the spring and piston from the VMX and after doing the debur and honing, installed them in the 1000X .25 to see what kind of difference I'd get in fps between gas ram and spring.
A few notes:
There was a small flat spot in the original piston seal, so it got replaced with a brand new Vortek seal. The inside of the piston was kind of rough and knowing I couldn't get down in there to polish it out, I polished a stainless flat washer and dropped it in there with moly paste on both sides to give the spring something smoother to ride on.
The spring guide had both a plastic and metal washer on it and the plastic one was removed and the metal one polished up for the other end of the spring.
None of those pieces had anything remotely resembling lubrication on them, they were bone dry. The only places I found anything that might be lube were some black goo around the piston seal and some yellowish stuff in the slot on the bottom of the piston for the cocking arm, so if you got one of the Amazon VMX rifles, I'd guess it's a safe bet yours has next to nothing for lubrication and you're going to need to.
The one other thing I did because I've been wanting to try it was to clean that cocking slot very well and put a thin layer of 2 part poly epoxy in there to see if it would help with the cocking noise of the arm sliding against the piston. The stuff self levels and dries in under 10 minutes and with a little moly paste and a deburred and polished cocking arm end makes a noticeable smoother and quieter difference when cocking the rifle. Don't know how long it will last in there but we'll find out...lol
The difference in the fps numbers?? Very little actually except a way lower ES with the FTT's:
JSB King 25.39gr:
-With gas ram: average 560, ES 24, SD 7, FPE 17.68
-With spring: average 556, ES 21, SD 6, FPE 17.43
H&N FTT 19.91gr:
-With gas ram: average 621, ES 31, SD 9, FPE 17.05
-With spring: 618, ES 12, SD 3, FPE 16.87
I still have a short range hammer, only the spring version can be tuned more than the gas ram to make it quieter and the action now is most definitely quieter and smoother than the gas rammed version.
Now to just find time to at least lube tune the other 2 VMX rifles I have sitting here because it's a safe bet they both need it.