100fps loss...for one shot in the string?

[ptpalpha]

While shooting some chrony strings after my latest "tweaking" session, I was surprised to see the occasional shot (approx. 1 shot out of 20) clock at about 100fps less than all the other shots.  Before I look inside again, I thought I'd post this here to see if anyone else has run into this, and what, if anything, was found to be the cause.
My gut feeling is that it's a problem with the spring end, and only causes the problem at a certain spot on the spring's rotation.
Any and all comments are welcome.
The rifle is a Mk2 TX200.
Thanks,
Paul

[palonej]

Just a suggestion Paul.....but this happened to me and it turned out to be weird chrony readings.
I set up my chrony so I was able to shoot groups while checking numbers....got some weird readings, but accuracy never changed.
If I got a reading of 800 FPS while the rest were 890 you'd figure that pellet would not be a part of the group.....but it was. Weird!

[ptpalpha]

Thanks, Joe..I'm actually hoping that's the answer.  To be honest, I've been getting frustrated with my Pro Chrono, either continuous "error" readings, or often no reading at all.
I'll try another rifle and see what happens.

[45Bravo]

I had the same issue with the pro chrono also.

It turned out to be a low battery.

Also it was where on the screens I was shooting, if I favored the left side of the sensors, it was one reading, if I favored the right side of the sensors, it was almost 100fps different..

I replaced the battery, and never looked back.

(Also now I shoot from a rest at a target 10 meters away,  with the chrono 2 ft from the muzzle)
 the target is so I have a reference point to keep the pellet path over the same section of the sensors, "just in case"

[tjk]

Ah yes,....The chronograph. It can be a great tool for diagnosing problems, and can also be your biggest antagonist and anxiety inducing aggravation.  If you are hitting good groups, then put the chrony away. I rarely ever use mine for just this reason. It would only get regular use if I were a pcp shooter learning the power curve of these types of shooters. As you continue to shoot the rifle, it will become more and more consistent. Tuning a gun is rarely an instant 'fix'. It's the time you spend shooting the gun post tune that brings a tune to its fullest potential. JMHO.
 

[Motorhead]

Shoot further above the chrony's eyes .... find shots low and close to the eyes give more errors that shots 4-6" above them.

Only a suggestion ...

[Roadworthy]

Paul, did you have a corresponding "flyer"?  If you're shooting any distance and the 100 fps difference is "real" I would expect one pellet to hit a bit below the group in general.  If the group is normal I think the chrony reading is suspect.  Just a thought.

[lefteyeshot]

I wonder if the occasional bent or hard to insert pellet goes down the barrel a little slower?