Suppressor Delimma

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Bee
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Suppressor Delimma

Post by Bee »

New to Form 1 building and my first experience with two Form 1 suppressers I built.
My dilemma is the distinct performance difference between the two cans.

Data:
One can is 1.5” OD x 8” long with 8 baffles, the other 1.75” x 9” long with 9 baffles
Both cans share the following features: 60 degree cones, 2” blast baffle,0,375” bored, aligned symmetrically clipped (3/16 wide 0,200” deep), progressively spaced.
The 1.5” OD can has a DeadAir KeyMo mount with DeadAir muzzle brake. The 1.75” OD can is direct thread.

Subjective test results from last weekend using 300 blackout, 120 gr supersonic ammo, AR 15 platform:

1.5” OD x 8” long can: Pleasant sound at shooters ear and to partner standing 3-4 feet to the side. Comparable to my Sandman L. This suppressor stuff is easy ! Wash, rinse and repeat with the larger can.

1.75” OD x 9” long can: Very loud and unpleasant to shooter and person 3-4 feet to one side. It’s as if I did not clip any of the baffles. Wow, did the magic go ? This suppressor stuff is now confusing.
Bee
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Re: Suppressor Delimma

Post by Bee »

Bee wrote: Tue Feb 18, 2020 1:59 pm New to Form 1 building and my first experience with two Form 1 suppressers I built.
My dilemma is the distinct performance difference between the two cans.

Data:
One can is 1.5” OD x 8” long with 8 baffles, the other 1.75” x 9” long with 9 baffles
Both cans share the following features: 60 degree cones, 2” blast baffle,0,375” bored, aligned symmetrically clipped (3/16 wide 0,200” deep), progressively spaced.
The 1.5” OD can has a DeadAir KeyMo mount with DeadAir muzzle brake. The 1.75” OD can is direct thread.

Subjective test results from last weekend using 300 blackout, 120 gr supersonic ammo, AR 15 platform:

1.5” OD x 8” long can: Pleasant sound at shooters ear and to partner standing 3-4 feet to the side. Comparable to my Sandman L. This suppressor stuff is easy ! Wash, rinse and repeat with the larger can.

1.75” OD x 9” long can: Very loud and unpleasant to shooter and person 3-4 feet to one side. It’s as if I did not clip any of the baffles. Wow, did the magic go ? This suppressor stuff is now confusing.
Forgot to add the obvious question: Any informed or experienced insight into why the 1.75”OD x 9” long can is performing so poorly ?
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whiterussian1974
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Re: Suppressor Delimma

Post by whiterussian1974 »

With the info that you've given, the results are illogical.
The larger internal volume, and longer length after the "uncorking" at the muzzle, mean that something must be wrong with the larger can.
They are both the same design?
Maybe posting some pictures would help. Otherwise, this makes no sense.
Sorry. :(

The only thing from what you've mentioned, the brake must be diverting a substantial amount of gas off of boreline and causing retention in the 1st chamber.
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ECCO Machine
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Re: Suppressor Delimma

Post by ECCO Machine »

While I wouldn't expect the larger can to be dramatically louder as you're describing, excessive internal volume absolutely can work against you, causing pressure to attenuate too quickly and not do what it's supposed to do with internal features, like hitting the clips & disrupting laminar flow. This is a very common issue with overgrown rimfire & pistol cans, is why I have developed some pretty intricate coaxial designs to make oversized cans work well.
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Bee
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Re: Suppressor Delimma

Post by Bee »

ECCO Machine wrote: Thu Feb 20, 2020 11:10 am While I wouldn't expect the larger can to be dramatically louder as you're describing, excessive internal volume absolutely can work against you, causing pressure to attenuate too quickly and not do what it's supposed to do with internal features, like hitting the clips & disrupting laminar flow. This is a very common issue with overgrown rimfire & pistol cans, is why I have developed some pretty intricate coaxial designs to make oversized cans work well.
Thank you for the insight. As previously mentioned, I was also surprised at the lack of suppression with the 1.75 OD can. Like, WTF is going on ? The 1.5 OD can was good enough compared to my 30 cal Dead Air Sandman’s and to my ear.

I initially assumed the issue was solely with my clip dimensions. Changed out direct thread mount and installed a Cherry Bomb muzzle brake. Test fired yesterday with noticeable reduction of sound energy at my ear. Not ear ringing any more.

Next step will be to test with precise clip alignment. Purchased some 3/16 key stock today and now have precisely aligned. Initial clip alignment was ....OK, but nothing like it is now.

Not much else I can do with internals. Can is built and fired.

From your comment, seems can may be more suitable for higher pressure 6.8 or 308 caliber. I’ll test and see just for grins.

Seems my first can is a real pig, a great conversation piece.
The second, 1.5 OD can, was definitely an improvement and now mounted on a 300 blackout AR. Shot two hogs with it last Saturday night. Third one will be built once Form 1 is approved.
Bee
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Re: Suppressor Delimma

Post by Bee »

whiterussian1974 wrote: Thu Feb 20, 2020 10:34 am With the info that you've given, the results are illogical.
The larger internal volume, and longer length after the "uncorking" at the muzzle, mean that something must be wrong with the larger can.
They are both the same design?
Maybe posting some pictures would help. Otherwise, this makes no sense.
Sorry. :(

The only thing from what you've mentioned, the brake must be diverting a substantial amount of gas off of boreline and causing retention in the 1st chamber.
Both cans same design, except 1.5 OD can had muzzle brake and 1.75 can was direct thread. I though the 1.75 can would run fine with direct thread, but that thought was very wrong. Figured if my Sandman Ti direct thread suppressor works, mine would too. Subsequently installed a Cherry Bomb muzzle brake and it made a difference.

ECCO suggested the larger volume was playing a part in the lack of performance. I refer to his comments and my response for more details.
0101silent
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Re: Suppressor Delimma

Post by 0101silent »

Is it possible to rotate a few of your baffles to face forward like a silencerco switchback? A few rotated baffles towards the middle could make a difference.
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d_lish
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Re: Suppressor Delimma

Post by d_lish »

How big is your first chamber?

I read too big of an expansion chamber can cause excessive pressure out the front, most likely dependent on a myriad of variables..
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