The Problem with Silenced 300 AAC Blackout…

June 3, 2012

http://www.youtube.com/watch?v=7rqFVh5U5-w

I just walked in the door from the Cedar Ridge Carbine Match out here in San Antonio. Naturally I had brought along my 300 AAC Blackout rifle and silencer, since the larger bullet gives me a hair more wiggle room in the scoring department (and did in fact help eliminate a penalty or two today) and the silencer is just tons of fun to use. But I ran into a problem that I had not anticipated, one that makes me re-think using a silencer for competition shooting…

Time is everything in USPSA / IDPA / 3-Gun style competition shooting. The time you take to knock down the targets is the single most important scoring metric available, and the only way to accurately record your time on a stage is by using a computerized timer. The timer counts from when the buzzer goes off until it hears the last round downrange, and that’s your time for the stage.

Therein lies the issue. These timers are designed to pick up on the traditional loud bangs of firearms going off, using cheap sensors to cut down on the price and therefore not very sensitive. So when you throw a silencer into the mix its a shot in the dark as to whether the timer will pick up on the (comparatively) whisper quiet reports of the firearm.

Thankfully my RSO’s timer was able to pick up my shots, but the nagging question in my head was whether this would be exception to the rule. I have my rifle zeroed with the silencer attached, a factor that drops the point of impact a good few inches compared to the standard configuration, but the question in my mind as I prepare for the summer competition season is whether I should keep it that way. Or should I swap back to my 5.56 gun and forget all this silencer nonsense, since that will definitely be picked up by the timer.

There are definite benefits to the 300 AAC Blackout round. There are definite benefits to a silencer. But I think I may have found the one scenario where a silenced 300 AAC Blackout rifle may actually be more of a hindrance than a help. Guns are loud and obnoxious, and when your score depends on a cheap mechanical sensor picking up the shockwave from your muzzle that’s exactly what you want.

11 COMMENTS

ThatKenGuy June 3, 2012 At 10:30

I haven’t tried my suppressors with my timer. Although I have found that they’re still fairly loud, from the supersonic crack. My Pact MKIV is pretty sensitive, and adjustable. So picking up a timer that you’ve adjusted to register suppressed shots might be your way around this. Although you’ll probably find it too sensitive when at a standard range with others.
- Mike in NC June 3, 2012 At 10:54
  
  I could be wrong, but I suspect that Nick is using the heavy (220 grain) subsonic flavor of 300 BLK and therefor has no supersonic shock-wave to detect. Supersonic 300 BLK usually falls in the 115 to 150 grain range.
  - ThatKenGuy June 3, 2012 At 11:02
    
    Nick said he had his zero for supersonic in the post around Memorial Day when he went hog hunting at Tyler’s ranch. But was using subsonic; why he didn’t get a hog.
    
    From my shooting suppressed I’ve found that most of the videos online don’t capture the sonic crack well, and the report seems to be much quieter as well.
    - Nick Leghorn June 3, 2012 At 11:40
      
      This was supersonic, 147gr PNW Arms ammo to be exact.
      
      Even with the supersonic crack its quieter than silenced 5.56.
Wade June 3, 2012 At 10:44

Would the .223 with a .30 cal silencer still be too quiet, or are you hell-bent in using the 300?
- Nick Leghorn June 3, 2012 At 11:35
  
  That would probably be loud enough. Its quiet, but not TOO quiet.
  
  The issue, however, is that my 5.56 racegun is MASSIVE and adding a heavy silencer is not a happy prospect…
Ken June 3, 2012 At 13:16

I tried to shoot my 223 AR with a Surefire suppressor at the three-gun match at AIM in GA last weekend. The timer wouldn’t pick it up so I had to take it off.
Patrick Carrube June 4, 2012 At 03:15

Considering that when I was RO’ing that I’ve had the timer get “bumped” by shooters reholstering their pistol, I’d say that the timers are plenty “sensitive”…
EthanB June 11, 2012 At 15:22

This may be an “Ask Foghorn” question, but at the risk of asking a question that has an obvious answer. Can someone expain why / how a silencer changes the point of impact? I think that there was an “Ask Foghorn” that answered the question if a silencer changed velocity (it does not). So why the change of impact with a silencer?
Jeremy L. Knauff June 26, 2012 At 15:03

Ethan, it’s because the added weight changes the barrel harmonics.
William Lindsay September 21, 2014 At 12:41

I have been told that if use subsonic round there is problem with gun not cycling . This is why suppressor needed
I just need dependable non jamming weapon .I don’t understand why sonic round cycling not issue
I have only fired sonic rounds but want to go subsonic. Any help with this much appreciate