22LR Rimfire Suppressor and Transonic Velocity Range

[zimagold]

Anyone hear of a suppressed rounds noise increasing as the speed of sound is approached?

I am new to owning suppressors. In my recent trips to the range, I have been surprised to find my bolt action seemed noticeably loader than my semi-auto with CCI Standard Velocity. Same suppressor, same barrel length (16”).
Doing some research, I found notes that sound generated by a projectile increases just before the speed of sound. The more margin to the speed of sound, the less noise. The recommendations I found were of making sure the suppressed round velocity is 7-8% below the current speed of sound given local conditions.

Indoor Range, 70 F = 1128 ft/sec (Speed of Sound)
Less 8%, 1038 ft/sec (Best Noise Reduction vs. Velocity Loss)

I went back to the range with a chronograph.
- 16” Bolt: 1072 ft/sec
- 16” Semi-Auto: 1033 ft/sec (I assume the velocity drop is due to energy being lost in the blow back action)

I guess I previously always thought of the speed of sound as a limit not to cross. This has me rethinking my subsonic loads for 300 Blackout and looking for another (Edit: 22LR) subsonic load. Anyone else experience this before?

[Circuits]

My biggest surprise shooting suppressed 22 has been first round pop. Empty/cold can volume, the first shot seems almost unsuppressed, then eerily quiet, almost dead silent except for action noise after that first shot.

Standard velocity is well below supersonic in all my 22 delivery systems, so I've never experienced the issue you're experiencing.

[zimagold]

I have been fortunate, the AAC ELement II seems to have very little FRP.

I was initially really disappointed in the Element on the bolt gun compared to ones I had heard before with friends. Then I tried it on my S&W 15-22 and I couldn't stop smiling. Definitely different.

Maybe I got a hot batch of CCI SV. Will try something else in the bolt and run the CCI SV through the 15-22.

[Great-Kazoo]

Outside of FRP, shooting standard velocity 22lr the DB reduction is good across the board. Most of my shooting is done using fed bulk pack, or CCI 40gr.

[zimagold]

Maybe my ears are playing tricks on me

Edit: I don't have a sound meter, so its just my perception.

[XC700116]

Is it possible that the sound of the action on the semi-auto is "drowning out" some of the perceived report on it vs the bolt gun which is only the firing pin and the report?

Dunno, just throwing it out there, I haven't had mine on anything but my bolt gun yet and all I shoot through it is Eley and CCI std.

[zimagold]

Is it possible that the sound of the action on the semi-auto is "drowning out" some of the perceived report on it vs the bolt gun which is only the firing pin and the report?

Dunno, just throwing it out there, I haven't had mine on anything but my bolt gun yet and all I shoot through it is Eley and CCI std.

Definitely affected by the action noise. Will be trying again with a few friends to get a general opinion.

[zimagold]

Has anyone tried this new ammo?

Federal American Eagle Suppressor - 45gr Copper Platted.

http://www.midwayusa.com/product/995...10-boxes-of-50

Edit: Seems like a good option with heavier bullet and cost of $28 per 500, if its ever in stock.

[Great-Kazoo]

I don't have any issues with the fed bulk pack or fed auto match.
Regarding the fired round being louder. I have a YHM Cobra in 45. On the 357 lever it's bolt action quiet. For use on my glock it's one of the worst sounding cans i've ever owned or shot. If one were to inquire for a purchase, i'd strongly advise against it. Not that this has anything to do with your question.

[DFBrews]

I had some fed bulk pack to close to supersonic come out of the mark ii I heard the bullet moving through the air more so than cci sv. The report was pretty much the same sparrow ss can