denton;
Good evening to you sir, I hope the day's been a good one for you and all who matter to you are well.
Two years ago now, the Shooting Chrony which I'd had for years began to show excessive readings at higher velocity. Strangely enough I was there with a buddy who was testing his which was a newer model of Chrony - a green one with the metal diffuser stands. He said he was getting odd readings from it on occasion as well, so we set the two up in tandem.
As a matter of practice and likely something that John has written recommending if I'm not wrong, I run a few shots with a .22 with the same box of ammo on all chrono days.
The crazy thing is that they stayed correct or at least within 20fps of where it should have been and both chronographs confirmed that.
When we chronographed a .17 Rimfire Mag my Chrony was a little bit too fast however. Then when I ran a few loads from a 6.5x55 my Chrony reading was 150fps too fast. Lastly I ran a few rounds through my .308 Norma which were loaded maybe 5 years back and in all subsequent chronographings had been consistent until that day when my Chrony readings were way too fast.
After a bit of correspondence with John and on his recommendation I picked up a Pro Chrono from a retailer here in BC who had one in stock.
All of the "known" speeds went back to "normal" again with the Pro Chrono.
Anyways that's my experience with a Chrony losing it's way, but again it was a very old one with the cardboard light diffuser holders - pre metal rods - and it'd served me for decades so I got good life out of it.
Hopefully that made sense and was useful to you or someone out there.
All the best.
Dwayne
Edit;
Both were Chrony's but different ages.
Last edited by BC30cal; 05/22/22. Reason: checked my notes - both were Chronys
