.22 LR going supersonic

I bought a brick of cci subs a few years ago, 50% we’re running too hot, have been using eley 38gr since , absolute tack drivers out of my cz455 and all stay subsonic even in cold weather 👍🏻
That's interesting, why would cold weather make them go supersonic?
 
That's interesting, why would cold weather make them go supersonic?
Cold air is denser, making she speed of sound slower so subsonic rimfire ammo that’s running close to the edge is more likely to go crack at say -2’c than at 20’c it’s all pretty marginal but I’m sure it makes a difference on the cold nights .. I learnt this while trying to work out why said boxes of cci sounded like an HMR half the time ,, 🧐
 
Cold air is denser, making she speed of sound slower so subsonic rimfire ammo that’s running close to the edge is more likely to go crack at say -2’c than at 20’c it’s all pretty marginal but I’m sure it makes a difference on the cold nights .. I learnt this while trying to work out why said boxes of cci sounded like an HMR half the time ,, 🧐
Hmm, ok. Never thought of that.

A quick Google...
Screenshot_2024-11-13-09-34-20-464_com.google.android.googlequicksearchbox.webp
 
Have you tried shooting some past a chronograph?
Perhaps post some figures if you do.

Cheers, Ken.
 
I had the same issue with cci, tried all the brands I could lay my hands on, settled on eley subs 38g. Also use zlang for real close.
Eley subs below.
 

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For target shooting I weight 22LR . The round weight difference on SK match are up to 1.2 grain .
So the velocity vary as well .
 
Recently tested Eley Sport, Club and Contact, all supposedly subsonic. I need to dig a chrono out because my ears tell me Eley’s specs are nonsense.
See below - I chrono’d a number of Eleys when doing an ammunition test, 16” barrel T1X and Garmin Xero chrono.

IMG_7021.jpeg
 
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