Suppressors Using a 7.62 suppressor on a 5.56 weapon.

Praetorian_6

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Gents,

I have 2 Knights QDC suppressors going through the tax stamp process. They are both for 7.62/.308 cal rifles, which will go on my .308 ARs.

Now, I'm picking up an 11.5" 5.56 Aero-precision pistol, and I'd like to avoid purchasing 5.56 specific suppressors if the 7.62 suppressors will work 90% as well. With that in mind, I will have a knights 3-prong flash hider with a 3/4x24 thread pitch. The 5.56 barrel has a standard 1/2 x 28 thread pitch, which brings me to my questions:

- What risks are there in using a thread adapter and mounting my 3-prong knights flash hider & QDC suppressors? (will heat cause enough distortion to cause rounds to contact the suppressors?)
- Will a 7.62 flash hider still be reasonably effective on a 5.56 gun?
- Is the juice worth the squeeze? Will the suppression still be worthwhile?

Thank you.
 

MinnesotaMulisha

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    I've used a thread adapter with a can without any issues. Just make sure when you install it, you use some type of clearance rod to make sure the can is straight with the bore so you can guarantee you won't get a baffle strike.

    I cant answer your second question.

    I run a 30 cal can on my 5.56 without any issues and it still works.

    It may be louder, but I'll never know.
     

    Huskydriver

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    I would double check everything with an alignment rod after you get it all tightened up.

    Also your 7.62 cans will probably sound better than a 556 can fyi and will have less back pressure
     
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    HenryTheAce

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    Personally I would not use a thread adapter. A 762 flash hider will be fine on 556 (as for its effectiveness I don’t know) but.... you’ll have a suppressor now, so why shoot un-suppressed? I run a couple 30cal cans on 556 rifles, they work great. Maybe a couple DB’s (which I can’t notice) louder but the biggest downside will be weight/size.
     

    Praetorian_6

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    I have not been the type to worry about an extra pound or two. Thanks for the replies guys. I'm not sure if Knights makes a compatible muzzle device for a 7.62 can with the correct thread pitch for a 5.56 barrel. Hence, the thread adapter, but I haven't explicitly asked. So, I will.
     

    SmokeEater406

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    I’ve been using a SureFire 7.62 can on 5.56 ARs and a 6.5 CM bolt gun. Works well and I would never be able to tell the difference compared to a caliber specific can for the 5.56/6.5.
     

    HenryTheAce

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    I’ve been using a SureFire 7.62 can on 5.56 ARs and a 6.5 CM bolt gun. Works well and I would never be able to tell the difference compared to a caliber specific can for the 5.56/6.5.
    Bet you would with a TBAC Ultra 9 in 6.5 on your 6.5 bolt gun... ask me how I know... night and day difference.
     
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    db2000

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    I have not been the type to worry about an extra pound or two. Thanks for the replies guys. I'm not sure if Knights makes a compatible muzzle device for a 7.62 can with the correct thread pitch for a 5.56 barrel. Hence, the thread adapter, but I haven't explicitly asked. So, I will.
    With the QD attachment on the can, Knights will make a flash hider for 5.56 thread (1/2-28) as opposed to your 7.62 (5/8-24). I agree with not using an adapter. I’d blue lok-tite the flash hiders to the barrels. I also use a lubricant between the flash hider and the QD to prevent seizure. Like others have said it works fine and the sound difference is negligible. There’s tons of tests/reviews online about this.
     
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    Praetorian_6

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    So, as it turns out, the only 3-prong 5.56 flash eliminator on their website lists compatibility only with 5.56 QD cans. However, the sales rep I've been working with says that they have one in the correct thread pitch that will work with 7.62 cans. I asked him to place it on order.
     

    HenryTheAce

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    So, as it turns out, the only 3-prong 5.56 flash eliminator on their website lists compatibility only with 5.56 QD cans. However, the sales rep I've been working with says that they have one in the correct thread pitch that will work with 7.62 cans. I asked him to place it on order.
    Hell yeah! Nice! That’s awesome.
     
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    BGE541

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    My 22-250 was a factory bull barrel so just chucked it up and threaded 5/8x24 plenty of meat left and all my cans are direct thread 5/8x24 so easy peasey
     

    AlphaThree

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    Bet you would with a TBAC Ultra 9 in 6.5 on your 6.5 bolt gun... ask me how I know... night and day difference.
    That noticeable?

    i would like to know as well. I ordered a .30 Dominus mainly for my .260 but to also use for 300BO. I didn’t get the 6.5 because I didn’t think the sound suppression difference would be noticeable, much less significant. There may be a metered difference but I would be shocked if it’s “night and day” difference by ear. Speaking from experience in shooting 5.56 through a .30 can
     
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    tacops1

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    Love the silencer co omega 7.62 for AR platforms using their flashiders. Just switch out the front cap between .30 and 5.56 and rock n roll
     

    HenryTheAce

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    i would like to know as well. I ordered a .30 Dominus mainly for my .260 but to also use for 300BO. I didn’t get the 6.5 because I didn’t think the sound suppression difference would be noticeable, much less significant. There may be a metered difference but I would be shocked if it’s “night and day” difference by ear. Speaking from experience in shooting 5.56 through a .30 can
    I can not speak for the Dominus as I have not received mine yet.. but what I was saying to him if you scroll up and read was the sound difference between the surefire 762-rc2 and my TBAC ultra 9-6.5 is very noticeable and is in fact night and day to me. To be fair the 762-rc2 is already a loud can as it’s primary purpose was not for ultimate suppression. I’m sure the Dominus and an Ultra 9 6.5 is not noticeable in sound difference. I’ll find out soon when I receive both my Dominus’s ;)
     

    BGE541

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    i would like to know as well. I ordered a .30 Dominus mainly for my .260 but to also use for 300BO. I didn’t get the 6.5 because I didn’t think the sound suppression difference would be noticeable, much less significant. There may be a metered difference but I would be shocked if it’s “night and day” difference by ear. Speaking from experience in shooting 5.56 through a .30 can

    Read what Ray wrote on the new Gen 2 can... not a huge difference in sound 30 to 6.5
     
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    Pappasniper

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    A 762 brake will work just fine on a 556 gun, as will the can. The only downside to running a 762 can on a 556 gun is size and weight IMHO. They make them plenty hush hush just kinda big and bulky if you can find the right adapters to make it work without getting brake on crooked and blow up your can. Double check alignment when you get it on.

    PB
     

    akmike47

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    A 762 brake will work just fine on a 556 gun, as will the can. The only downside to running a 762 can on a 556 gun is size and weight IMHO. They make them plenty hush hush just kinda big and bulky if you can find the right adapters to make it work without getting brake on crooked and blow up your can. Double check alignment when you get it on.

    PB
    Thank you necromancer, sure hope this being from 2020 he still wasn't waiting on an answer lol
     
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    Bravo6niner

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    Let me find the part number but knights makes a 1/2x28 break for the 7.62 can. I might even have and extra I can let go of
     

    pineoak

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    Given how much sound comes out of the ejection port... just run the .30 cal can.

    Thread adapter should work fine.
     

    AMGtuned

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    This is like the 3rd or 4th thread, revived, regarding this topic. 🤦‍♂️

    ~3db. 3db, is roughly the difference using caliber bored endcaps. 3db can also be detected by the human ear; so one would be able to, and may hear the actual difference.

    Ti can spark when you get it hot.

    Small frame AR bolt drop ~115-116db.

    I'm not a claimed professional anything. Research and homework, combined with personal experience. But this argument, 4 threads wide, is seemingly akin to "I put an AI chassis on muh Savage, so they must shoot the same now".

    Everyone's host is different. Everyone's use case is different. Seems in the F4 world, SOP is "whos got the super hush hush stuff", and nothing else matters.

    PEW Science is awesome. What Jay does, AWESOME. The suppressor market needed him and his findings. But just like the news; read/listen, and come to your own conclusions. Unless you duplicate Jays test weapon systems, in his AO (or similar conditions), your results will be different. Period.

    3db is a lot. 🤷‍♂️
     

    Praetorian_6

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    Yeah... OP here. So, I ended up buying the flash suppressor I needed directly from knights. Put the adapter in a box. So, my 7.62 suppressors are compatible with my 11.5" AR15 Aero M4, my KAC SR30 (stock flash suppressor), my Aero M5 (5/8" MAMS), and my future SR-25 (3/4" MAMS). Cross compatibility with these high end suppressors is what I was going for.

    As a side note, I got the QDC/CQB back in 2020. The QDC/PRS is supposedly coming up for invoice now. I will still need to file for the tax stamp. Gotta love a 2-3 year wait. Still don't have the SR-25.
     

    akmike47

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    I necro raped the fuck out of this this thing something bad. How it popped up on me is a true wonder.

    PB
    The last update brings up a lot of old threads. Sometimes I see some shit I forgot about though.