Hi Footloose,
I have spent a lot of time with my .177 DRS Classic in 500mm. I am trying to get it to the point where it can be my backup FT (Hunter Class) rifle. I am looking to shott 13.4 gr pellets as I have had a lot of luck with the FX and JSB original monsters with the same pellet liner in my Crown Mk II. After 5 months of on and off work on it I am finally getting there.
The issues I ran across are the same as for almost any new rifle. I had trouble finding the right combination of regulator pressure and hammer spring compression to really tune the rifle. When it is "happy", the rifle shoots really long strings (80 shots +) with an SD 0f 1.7 and an ES of 7. Off just a bit from that spot it goes south fast. I also polished the valve pin and greased up the rear o-ring and gasket on the valve cover to keep the valve pin from sticking (even slightly). I also polished the hammer, the ends of the hammer spring, and the trigger sear for good measure.
The place that needed the most work was the barrel inlet. Early on I was getting three or four bad flyers when shooting the AGN 30yd Challenge targets. I would have 12 - 14 x's (out of 20 shots), but 3 or 4 7's and 8's. Extensive internal polishing of the barrel inlet, the actual transfer port hole, and the liner has for the most part made the bad flyers go away. And I mean a lot of polishing on the barrel liner. The breech end was initially so tight that I had to really push the cocking lever forward to seat the pellets.
I also found that the o-rings that came with the rifle to keep the liner centered in the barrel housing seemed too small. The liner was kind of loose in the housing before I tightened the liner lock nut. I found the carbon fiber liner tube did a better job and am now using that (still haven't decided whether or not to epoxy it to the liner). Also found that the new generation of liner lock nuts do not have o-rings (7 x 1 NBR 70) in them like the ones on my Maverick or King. It's the same part number, but in the past the .177 and .22 liner lock nuts had two o-rings in them. I noticed the liner rattled around in this also. I called UA and after talking with Travis for a bit he went back into the shop and found me an old one and I bought it.
As it sits now, in its new FORM Stock, the rifle is shooting a very consistent 818 fps with the FX 13.4 gr pellets and I am getting 80+ shots from 250 bar before falling off the reg at 110 bar (oh ya, I bought the Carbon Fiber barrel tube from Europe Airguns). It is loud, so I am running all 4 modules of my Huma 40-4 Avalanche moderator to make it backyard friendly. I may be trying it in a friendly FT match next weekend. It shoots my home 50+ yard FT targets with 1.5-inch KZ's just fine (depending on my ability to read the wind).
Cheers,
Greg
