Curious on suppression quality with a 7.5 to an 8 inch barrel? I've read so much I have a headache and of course there are lots of opinions. Just curious from those running a similar setup

Thanks

A little shorter than you're asking about but in the ballpark.  I'm running a 7 inch Adco barrel with a Gemtech MK9K.  Haven't measured it with a decibel meter or fired it indoors without hearing protection, but I'm happy with the results when shooting outdoors.  Both subsonic and normal ammo are very comfortable to shoot without ear muffs or plugs,  You can hear the supersonic crack of normal rounds going down range, but the report does not causing any hearing discomfort.

Pete

I only run subs through my Gemtech Trinity Talon combo upper and it is quiet enough for the fun I have.

Not sure about your question, but 7.5 is in the "unknown" range for subsonic versus sonic.

115s+124s will probably be sonic; 147s may not be sonic.

This is driving me crazy, lol. The unknown. Which I understand. I have a 7 inch handguard, and was hoping to keep the barrel fairly flush for shooting unsupressed. I realize I could use a exended flash or something. I dont however want to lose much if any suppression effectiveness on 115-147gr.

Wondering if I should go back to a 5.5 or if I can get away using the 7 inch? sounds like 7.5-8 may be borderline.

Thanks

I have a 5in on mine and I never shoot unsuppressed, just don't see any reason to.

A 5" barrel should keep all rounds subsonic so you don't have to shoot subsonic ammo.

Really? Most 9mm hand guns have a barrel under 5 inches. Have read most 115gr rounds go sonic in most full size hand guns? Is this wrong?

No, you are correct about 115s being supersonic out of barrels under 5". I think KILLERB6 is mistakingly referring to 22lr.

Standard pressure 115 is going to be brand dependent and too close to call but considering "real world" results versus published ballistics, I'd bet subsonic.

I ran a 5.5 and now 4.5" 9mm barrels in my M16/9 and also with a RDIAS.

I have found factory and my handloaded 115gr fmj loads to be supersonic in just about everything I've ever shot them through - Glock, Beretta, SIG, M16/9, etc.

I suspect that if you got some 115gr fmj loads that were subsonic in the shorter barrels, you would have some malfunctions in semi-auto pistols with this ammo.

I have found 147gr fmj, occasionally like in cold weather, to be supersonic in the Colt 10.5" 635 upper.  That's why I sold it off and went with a custom shorter barrel over a decade ago.  At the time I used the Colt SMG upper and also a suppressed M92.  If I downloaded my 147gr enough to eusure subsonic velocity in any weather in the 10.5" SMG barrel, the Beretta was not entirely reliable with this ammo - with an old AAC Phantom 9mm suppressor (designed for Beretta M92).

From my TROS 5" all 115gr and 124gr factory ammo is supersonic.  All 147gr are subsonic.

So you never tested any, but you're giving advice?

In most Semi-Auto firearms you have action noise to complete with.  It is pointless to try and supress a firearm to be quieter then the action noise.  I think you will still have super/sub sonic ammo with a 7" to 8" barrel  Look at Ballistic by the Inch They have a lot of good Info.

MAHA

Yea, you got me:  I have NOT "tested" every single 9mm round known to man.

If the MV stated in a given manufacturer's ballistic tables is less than the speed of sound (and I know, the speed of sound is a weak function of air temperature, so YMWV) then it's a fairly safe bet that your real world MV is also going to be less than sonic...at least that's the way I'd bet.  I sure wouldn't expect my MV to be a whole lot greater than the manufacturer's stated MV.

So yes, I am trying to help the OP out by correcting a statement someone made about all 115s being supersonic in 5" barrels and yes, the standard pressure (e.g. not +P or +P+) 115s I have run through a LW 5" are subsonic.

HTH.

You also need to factor in what suppressor & ammo you will run. SOME are quieter than others.  Buying a low end can could surprise you running next to a high dollar unit. Maybe not