large volume 300 blk cans - DB @ the ear

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airwolf
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large volume 300 blk cans - DB @ the ear

Post by airwolf »

It's been a while since I've been on here. Most of my posts have always been about achieving maximum suppression (DB @the ear). I have severely damaged ears, 24 hr a day tinnitus, severe hearing sensitivity and hearing loss. I now spend most of my days shooting a .22 bolt gun with a dead air mask and I still have to wear hearing protection for that.

So I've always wanted to attempt an AR in 300 blk and gave up on that pursuit, after considering longest barrel, carbine gas system, adj gs block, etc, I didn't feel I was going to be able to achieve low enough sound at the ear, since I know nothing about reloading and that seems to be paramount.

So just yesterday I purchased a Savage Axis II bolt gun in 300 blk and I currently have a 300 omega that I have never shot, its still literally sitting in the box. I bought this omega originally for the AR years ago before I understood DB at the ear, port pop, and backpressure. I quickly decided the omega was not my best choice, so its still sits in the gun safe, although I am considering attempting it on this bolt gun, (my ears are that bad)

But after just seeing this: https://www.thefirearmblog.com/blog/201 ... ering-day/ ......I am completely stumped on several things. This test of numerous 300 cans was best I have ever seen. All these cans are shot on a ruger bolt action using discrete ballistics 300 blk subs and the DB at the ear for the large majority of the cans is LOUDER than the muzzle? How is that possible, there is no port pop on a bolt gun, I expected the DB numbers at the ear to be mush less on a bolt gun than what they are and definitely not louder than the muzzle db?

The can that was king of the hill on this test was the Dead Air Nomax, which is now for sale as the Dead Air nomad L, and that can was absolutely incredible.

What further muddy's the water for me, is I also shoot a glock 17 with a rugged obsidian 9 that silencershop shows around 127 db at the ear. When I shoot this I wear doubled up hearing protection and it is the threshold of what I can handle with my ear issues. The obsidian 9 is also able to be used for 300 blk. Silencershop meters the obsidian 9 on a eight inch barreled banshee AR in 300 blk @ 126 db at the ear. This is the lowest db at the ear of any 300 blk can on an AR I've seen tested anywhere. including all cans tested on silencershop https://www.silencershop.com/rugged-obsidian-9.html (its the first video) This is quieter than the db @ the ear of bolt guns with large volume cans in the above test...what the heck is going on here.

Now I know when you don't compare suppressors under the same conditions, humidity, temperature, etc. the can be variances. But silencershop does pretty well at being consistent and I always check what the meter says on the host gun unsuppressed to see if the baseline is consistent with other tests.

I still can't wrap my head around the fact that a small diameter obsidian 9 can is metering quieter at the ear on a 300 blk AR with port pop, (at a good amount of decibels difference) compared to larger diameter cans on 300 blk bolt guns, all being shot with factory subs.

Here is silencershop testing the nomad L. https://www.youtube.com/watch?v=0NNFiar9HJY
On a 300 blk 9 inch barrel, its averaging 133 db at the ear. How can it be almost 7 db louder at the ear than the much thinner obsidian 9? A difference of 7 decibels is huge, even taking into account different conditions etc.

What am I missing here? Sorry for the long post. I have been researching suppressors and 300 blk particular for quite some time now, and all of a sudden all this recent data has thrown me for a loop for what I though I knew.
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dellet
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Re: large volume 300 blk cans - DB @ the ear

Post by dellet »

The numbers don’t show enough difference to really have any kind of conclusion. The next piece of data I would want would be to reverse the positions of the two meters. If the numbers held, I would shoot from a different location. There is a huge difference in noise at the ear depending on where you shoot. Is there roof, concrete floor, close to the berm.

I can tell the difference shooting from the same exact location, if there is more snow on the ground between sessions.

Something you might try, if location will allow, is to build an external sound chamber. It could be as simple as a foam lined barrel with a window big enough for the muzzle to pass through and sighting. You put the whole rifle in a silencer. There are a lot of things you can do to improve the area you shoot at.

An investment in loading equipment would likely pay huge dividends.

The omega is a good suppressor, try multiple brands of ammo, have some one else shoot while you listen, them work your way closer to the rifle.
300 Blackout, not just for sub-sonics.
airwolf
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Joined: Tue Jan 23, 2018 2:10 am

Re: large volume 300 blk cans - DB @ the ear

Post by airwolf »

Thanks for the reply.

Those are all good points. I only shoot outside and in a open area with the least amount of trees around me and on soft ground.

Shooting over snow is interesting. I've gotten a chance to since I got my suppressors, but I'm guessing when you shot over snow, it was even quieter?
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dellet
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Re: large volume 300 blk cans - DB @ the ear

Post by dellet »

Yes, you get noticeably less noise with snow. Anything that will absorb sound vs bounce it back helps.

As sensitive as your ears are you could probably shoot off a foam pad or shooting mat on the bench and hear a difference.
300 Blackout, not just for sub-sonics.
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