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Very Unusual CFX, CPL & Prochrono results

March 28 2007 at 10:24 AM
  (Login rjbirnbaum)
YC

I’ve had a B-19 for 5 years that I home tuned with tar, moly,and new Apex seal when I got it, but I’ve had a love/hate relationship with it (mostly hate) mainly cause I could never get it to shoot as accurately as I wanted. I recently added a GTX trigger which has helped but I still thought it should do better. I wanted to tinker myself and I was itching for a new gun so I bought a Gamo CFX and a Prochrono Digital. I figured between the CFX, which is known to be pretty accurate and easy to shoot, and the chrono I’ld be able to get a good read on the B-19’s mechanicals, a comparison on shooting technique of two different springers, and basically determine what potential to expect from the B-19. Of course, I also wanted to start tinkering with the CFX.

Part 1 - I wanted to start out by getting a baseline on both guns with the Prochrono and various pellets. This is where the fun begins. It was a less than ideal day, very bright sun and windy. Here’s the sequence from that day:

- B19 w/CPL avg 630 fps +/-8 I thought this was very low, must be a spring problem.
- I wanted to quickly check the chrono so I grabbed my Marksman 2004 w/CPL but I got 354 fps. I thought this was very low, but an extremely consistent string. I next tried the 2004 with a Gamo Match and got 413fps which is about what I’ld expect (again very consistent string).
- Then I tried the Gamo Match in the B-19 and got about 775fps (very consistent string,..I’ll stop saying this because all my chrono strings were consistent). I thought this was still low for the B-19, and 150 fps is big difference for pellets that are suppose to be only 0.4 gr difference.
- Next was the CFX:
- CPL 727 fps Surprisingly low
- RWS Suprdome 866 fps Seemed about right.
- FTS 741 fps Was expecting higher, this is >2ft/lbs below the RWS
- CPL 726 fps Still very low but matched the first CPL string

I called it a day but didn’t know what to conclude. The conditions were lousy, the CPL results were crazy, but the strings were extremely consistent, no read errors on the Prochrono, and the CFX/CPL result was repeated identically.

Part 2 – Last night I rigged up some lights indoors just to see if I could get the Prochrono to work inside and do more testing. To cut to the chase, it worked fine and I got nearly identical results.

Part 3 – I brought a few pellets of each type with me to work today to weigh them on our professionally calibrated analytical scales. Guess what,…the CPL’s I have are really CPH’s. They averaged 10.6 gr. All other pellets seemed ok but the Gamo Matchs avg 7.8gr vs a nominal spec of 7.5gr.

My comments/questions/conclusions:
1. Watchout for CPL’s that are CPH’s!!!
2. The Prochrono seems great, easy to use, not sensitive, no read errors, and I’m concluding that it is calibrated precisely based on the Marksman 2004 Gamo Match results, and overall repeatability/consistency.
3. My B-19 needs some work. It averaged between 9.4-10.6 ft/lbs. I have a new JM spring and seal I will try.
4. I’m not sure what to think about the CFX. The RWS Superdome results seem OK. A little low, but maybe that’s normal for brand new gun. However, the variation in muzzle energy between the RWS (13.5 ft/lbs) vs FTS (11.1 ft/lbs) & CPH (12.4 ft/lbs) is bigger than I would expect. Comments?

Sorry for such a long post, but I would appreciate any comments particularly on the CFX.

Regards,

Ron

 
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