by norton850 on Sun Dec 18, 2016 9:30 pm
Hi,
so after a good deal of time and wasted expense, here's where I have ended up.
When the gun was dry fired the hammer hit the back of the valve chamber and distorted the main valve hole ie. minutely reduced the diameter of the hole.
As a result of the narrowing of the hole diameter the main valve pin was unable to seat back on the main valve. I had initially thought the main valve stem was 'bent' but this was not the case. The replacement valve stem also would not sit fully home on the valve seat.
I bought a small hole gauge to measure the valve hole and noted the reduction and the size of the main valve to be 3.7 mm.
I bought a 3.7 mm drill off ebay and using a hand drill chased down the main valve drilling, the metal is very soft and only a few turns was required.
I had thought of using a hand reamer as this would be my usual choice of tool for an accurate hole but this seemed to have worked well with just the drill.
Other points to note
1. The use of the .177 hammer/spring (including the screwed threaded into the hammer) is all about getting the gun to FAC compliance at less than 12 foot pounds.
The physics behind this is that the hammer opens the valve for a microscopic duration allowing air through the gun and into the barrel - pellet velocity is a product of pressure and volume so a longer duration and higher regulated pressure will fire at higher velocity, my rifle has the BTAS regulator from new setup for the sub FAC gun .
So lower impact speed will open the valve for shorter duration and this setup delivers the 12 foot pound limit.
Personally I think any design that physically damages the gun when fired without being pressurised is suspect, but I do see that this was a case of operator error causing the damage.
Still you live and learn, I heard Ben Taylor had retired, I wouldn't blame him in any way for this outcome.
One last point, I had a heck of a job removing the hammer spring adjuster - it is loctited in place but no amount of heat helped and in the end I dremelled a deeper slot into the brass head and used a large bladed screwdriver to remove the brass end cap (it just chewed up with the standard slot and heat).
I replaced this with the steel one now available that has a hex slot cut in it for adjustment, the fitment/adjustment for the hammer spring guide is now the same as with the brass slotted screw and a much better solution (brass is way too soft for a regular adjustment)
I believe that if you want to FAC to gun all that would be required would be
1. Standard hammer
2. The hammer weight setup from the .22
3. The reg pressure to be raised from the 80 bar to around 120 plus.
So in the end my gun is now working (it has been in a cupboard for years although it does still look like new)
The moral of this tale is that the fix was a £1.99 HSS 3.7mm drill and the cost of investigation and unnecessary spares/tools was substantial, I now have a new spare main valve stem, main valve, valve spring etc. tools are never in my mind wasted and I have these for future use.
Overall though having spent a great deal of time on this I 100% understand how the gun works, and how to assemble disassemble and service.
I also note that my air cylinder is now well past its inspection date.
I am thinking of going FAC for other reasons but would probably sell/px the cyclone - it is a lovely gun but I think it might be better to go straight for an unmodified ie FAC gun.