9mm Sub-Sonic 115-124gr - is louder than most 147gr ammo?

[Another_Kelley]

Mods- I have this same thread posted in your "Handloading" sub-forums as well - I realize it's more of a Reloading question - but I'm getting crickets so far....

Lately I acquired a couple different .355s to play with - all of which are 115gr - 124gr. I've used 147gr bullets exclusively up to this point and got excellent suppressed results with an Octane can using both Unique & V-3N37. Very pleasant to the ear, fun to shoot etc ...

That all changed when I tried those two powders with a 124gr fmj round-nose. The best way I can describe it - is a "first round pop" - every round. Even downloaded into the 950fps territory - I'm hearing a VERY different report compared to a 147gr bullet with the same powders.

This morning I was able to find a can of Tightgroup I had tucked away- ended up in the neighborhood of 3.5gr under a 124 before I started getting an 'acceptable/comparable' report to that of the 147s - however I still feel like the 147s with 3N37 are noticeably quieter.

I have a feeling this is no doubt a well known phenomena to everyone (but me) out there loading lighter 9mm sub sonic ammo... I'd love to hear what your favorite powders/recipes & ultimately secrets are for getting the 115s & 124s to not bark so loud - Thanks!

 

[adcoch1]

It would appear at first glance that you are still supersonic, are you chronoing your loads? If so how close to supersonic are you getting? Not picking on you're research, but could you have overlooked something? Like maybe a short COL boosting the pressure of a small charge enough to put you supersonic? Also, what elevation are you shooting at? You may be closer to the threshold than you realize. Just trying to brainstorm here and get the topic moving.

 

[Another_Kelley]

Yep, they're definitely not cracking. It's more of an unpleasant 'pop' - like excessive powder-burn inside or at the muzzle of the can I'm hearing... It was never present with any of the 147gr ammo I've loaded.

Initially I was going by ear - started high and worked my way down until my loads were matching what other data suggested should put me in that 1050 neighborhood... They were still loud enough that I finally shot a few over the chrono cause I was pretty puzzled at that point. Then I proceeded to download further into the 950 realm until I realized there must be an issue with my choice of powder/seating depth/bullet tension, cause the unpleasant pop was still present.

I started loading rifle ammo a decade ago but never handloaded any pistol until picking up a can and being astonished at how loud typical super-sonic 9mm ammo was while 'suppressed'.

Also, I've yet to try any commercial sub-sonic 9mm ammo - I was thinking I might try to find some 124gr subs somewhere to compare.

 

[hq]

It appears that you need to experiment with faster burning powders. If there's a distinct muzzle "pop", the pressure inside the barrel is still high when the bullet leaves. For example, subsonic rifle caliber rounds are best loaded with fast pistol powders at approximately 30% of the usual powder charge in grains. Hodgdon Titewad and Clays or Alliant Bullseye are the kind of powders you might want to try. And be careful, max charges are really tiny with these combinations.

 

[Another_Kelley]

It appears that you need to experiment with faster burning powders. If there's a distinct muzzle "pop", the pressure inside the barrel is still high when the bullet leaves. For example, subsonic rifle caliber rounds are best loaded with fast pistol powders at approximately 30% of the usual powder charge in grains. Hodgdon Titewad and Clays or Alliant Bullseye are the kind of powders you might want to try. And be careful, max charges are really tiny with these combinations.

That makes good sense HQ. I had a feeling this might involve finding a new powder... but with all the options out there for 9mm I didn't want to start trying 'one of everything'. Thank you very much for your input!

 

[paradox998]

I found that 124gr bullets do go supersonic and are quite loud even with a suppressor. 147gr RN bullets stay subsonic work much better with my suppressor. Just the other day I was shooting and the rounds were much louder than normal. When I checked the ammo I had picked up a box of 124 reloads rather than then heavier ones. I changed to the 147gr loads and difference was night and day. My guess is that 115 gr rounds would also go supersonic and have a loud crack.

 

[JeffG]

I too, would stick with 147's. If you're handloading, Blue Dot and 700x might be good powders to get that "cat sneeze" load. Powders that might still be burning beyond the muzzle will increase report, can or not. With a semiautomatic pistol, don't forget you have to retard the bullet's exit somewhat, to get the action to function with light loads. Heavier bullets will help.

 

[CDR_Glock]

I have been handloading 147 gr Berry bullets using Power Pistol with excellent results for subsonic. At max load, I am around 1000 FPS.

 

[MachIVshooter]

It would appear at first glance that you are still supersonic, are you chronoing your loads?

+1. lighter bullets at the same velocity use lighter charges, ergo lower pressure, so should be quieter. It's possible that you're getting higher uncorking pressure with a slower powder that burns more completely behind a 147 gr., but if you're not actually chronographing, I suspect you're faster than you think.

Keep playing with the load, definitely invest in a chrono. Some loads do produce significantly more noise suppressed than others. American Eagle 147, for example, while definitely subsonic, is almost as loud as 115 gr supers through every can I've tried. That's not just my ears; my B&K 2209 confirms that it's 4-6 dB louder than my handloads and a number of other factory 147 loads, which means it's hitting high 120s and low 130s, which is getting into .45 ACP SPL.