I shot some a couple of weeks ago [65*ish] through a suppressed cz , every shot went supersonic . I just looked and the box says 1100fps and I'm maybe 60-70 feet above sea level .

Doesn't getting close to supersonic speed like this defeat the purpose of target ammo ?
It didn't shoot well in 2 cz's and a savage .

That stuff shoots great out of all the guns I've shot it out of. That being said, it wouldn't be the first time a particular ammo that shoots well for several guns, doesn't shoot well for any particular gun you try. It's been very consistent for me but also, it is not a true match grade ammo .

Jim ,

I was just surprised that it was making the supersonic crack - I thought at lower elevation guns got less velocity than at high elevation . Staying under supersonic velocity is where the accuracy comes from .

Does this ammo stay subsonic for you ?

I shot some RWS HP subsonic right after the Tac-22 and it was subsonic and shot bugholes at 50 yards .
All the standard velocity I have shot in my three 22's have shot good too great only this ammo has not .
Maybe I got a hot loaded [bad] lot .?.
I'll just use it on the trapline I guess .

It isn't the bullet velocity that is critical as much as flow field velocity. Nose form is the issue.

My 10-22 likes it a lot. It won't chamber in a minspec match chamber in another rifle. Tac bullets in the lot I have mic at .225" diameter.

Mike i shoot it out of my guns at the range and have hearing protection on and have no idea if it goes super sonic or not. Have you thought about calling Norma and see if they won't exchange it for you. At very least I would think they would want to know they have a QC issue at hand.

DigitalDan ,

Not exactly sure what that means , but I'll take your word for it -grin.

JimHnSTL ,

No I haven't -that's a good idea -thanks .

The reason I mentioned this thread is I'm wondering why they get so close to supersonic , if a round goes supersonic then subsonic the accuracy is out the window ?

I've been shooting some Norma Match and Norma Tac22. Not surpressed so I can't comment on supersonic crack. Next trip to the range I'll chrono both and report velocity. Accuracy has been good with each firearm, pistol and rifle. Match slightly better in the CZ 452. Limited sample size so far but I'm happy with both.

Never having used a suppressor I don't know what to expect with or without the sonic crack. Have you tried other subsonic ammo with it and noticed a big difference? Wearing double ear protection (plugs and muffs) I guess I've never paid attention to the noise.

Reading your posts again I see that you have shot many other subsonic brands. I'll still see what the Chrony says and post the results.

Wiki says the speed of sound is 1125fps. 1100 seems to be pushing the limits to remain SS in everything. I believe that's why real match ammo is usually rated at 1080.

Doubt that the crack is having all that much negative effect on your accuracy. Probably just need to look elsewhere. Everyone with a .22 rifle needs a companion handgun to burn up the culls.

FWIW I shot 10 rounds of Norma Tac this evening over a Pro Chrony. Used a CZ455 with factory 16" barrel. Results:

1069 Avg FPS
23 ES
9 SD

Too cold and getting dark to do more. Hope this is helpful.

I just shot some in a new to me Remington 541S, it was one of the more accurate ones of several. I agreed that 1100fps is on the edge of supersonic, but with ears I did not hear or feel any difference from match ammo that was at 1080. Funny thing was the rifle did not like Norma Match.. Each one is unique to itself.

A sonic crack/boom occurs when air is accelerated past the speed of sound. In simple terms air is not compressible (fluid) until it reaches that threshold (Mach 1), then is compresses into a shockwave (sound). A long sleek bullet form such as a VLD profile promotes less acceleration on the linear axis while a blunt form (Flat nose/HP/Round nose) causes more acceleration. This is how "sub-sonic" bullet velocity generates supersonic flow/shock waves in the flow field around the bullet.

1100 fps is tickling the dragon's tail in this context and the speed of sound is variable, influenced by air density (altitude) and temperature.

All in all, it's not something to worry about insofar as accuracy is a consideration. It can defeat, to some extent, the purpose of a suppressor or other sound attenuation devices/objectives.

Air is not compressible until it reaches mach 1?

Not in the aerodynamic world. It behaves like a fluid and engineers of the plane design sort calculate it as such. Remember, we are talking an unconfined circumstance, not a scuba bottle.