Can .45 ACP Be Quiet? SIG’s Big Bore Suppressor

In our continuing coverage of SIG Sauer Suppressors, this week we busted out the big bore. The SRD45, for that most American of cartridges, the .45 ACP. Most people assume that .45 is the perfect suppressed round since most of its loadings are already subsonic. That briefs well, but so far has not been my experience.

In the past, I have found .45 to be the worst of the handguns to suppress, at least as far as noise goes. I am not an engineer, so I can’t tell you why. Maybe it has had to do with the massive bore diameter combined with relatively low pressure. For whatever reason, every .45 suppressor I’ve shot forced me to grab my earplugs. Until now.

Read About the Importance of Suppressor Maintenance.


  • Caliber: .45 Auto
  • Weight: 12 oz.
  • Diameter: 1.38 in.
  • Overall Length: 7.9 in.
  • Threads:  1/2 in. – 28 tpi
  • Attachment Type: Direct Thread
  • Material: Titanium & Stainless Steel
  • MSRP: $745
  • Manufacturer: SIG Sauer

SIG has done some amazing things with suppressor technology over the last year, and the handguns have not been left out. The SRD 45 features all the same goodness as the SRD9 we reviewed here, scaled up to a man’s round. The baffle design is different, but most of the internal design is the same, including construction materials. From our SRD9 review:

 One of the first considerations we should contemplate before purchasing a suppressor is what is it made of and why does it matter? If you’re going to go through the process paperwork and the waiting period, you want to make it worth your while. First of all, the materials SIG Sauer used in the construction of their suppressors are top notch. The shell for their SRD9 is titanium, with all stainless steel baffles. Many suppressors at this price point use aluminum after the first blast baffle, which willwears much more quickly than steel. The interior itself is made of K stacked baffles, not a monocore. A monocore baffle is a solid piece of metal that has sections machined out of it. The stacked baffle design that SIG engineered requires more machining but it helps on a few fronts.

The SRD 45 comes with both metric and English pistons, in .578 in x28tpi and M16x1mm LH respectively. It also includes a spacer to use in place of the pistons if you are lucky enough to own a .45 ACP carbine. The best part of the SRD45? Just by purchasing extra pistons, you can use the same can on your 9mm and .40 S&W pistols.

Why Pick .45?

This .45 suppressor actually works, it makes .45 ACP hearing safe. Excellent!

Step One — Now why would you choose .45? The .45 caliber is to pistols what .300 AAC Blackout is to rifles. When you look at suppressed choices, you are by nature of the challenge already limited by velocity. That is, for a truly quiet round, you must already be in the subsonic range of speed. When velocity has a threshold, in my opinion, you might as well shoot the heaviest bullet you can. The heaviest 9mm bullet I have ever seen is 165 grains. For .45 ACP, the standard is 230 grains. Questions?

Range Time

For a host, I chose to go with the Smith & Wesson M&P 45. This is an excellent platform, complete with a factory threaded barrel if you choose the right options package. The 10+1 capacity is a great to have with this caliber, and the Smith handles it nicely!

Article Continues Below.

For ammunition, I turned to Freedom Munitions. Not only was the regular re-manufactured .45 ACP reliable, it was hearing safe. But the true champion of the day was the 45 HUSH. Last year, Freedom Munitions spent some R&D time working on HUSH, a line of ammunition design specifically for suppressed weapons. Not only is it quieter, it features a powder designed to burn better in guns with mufflers. The 45 HUSH was definitely the fuel of choice.

The SRD45 has left me impressed, and that is getting harder to do these days. If you are in the market for a handgun suppressor, this one covers all of your needs.

Is Your Rifle More or Less Accurate with a Suppressor?

To learn more about Freedom Munitions, click here.

For more information about SIG Sauer suppressors, click here.

To purchase a SIG Sauer suppressor on GunsAmerica, click here.

About the author: Clay Martin is a former Marine and Green Beret, retiring out of 3rd Special Forces Group. He is a multi-decade and -service sniper, as well as 3-Gun competitor and Master ranked shooter in USPSA Production. In addition to writing about guns, he is the author of “Last Son of The War God,” a novel about shooting people that deserve it. You can also follow him on twitter, @offthe_res or his website,

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  • Pete July 6, 2020, 9:00 am

    If you’re not going to post tested db levels, what’s the point of a review? Maybe you should go into politics. That’s the kind of lame tricks they use.

  • BILLYBOB May 24, 2018, 5:41 pm

    Weight: 12 oz.
    Diameter: 1.38 in.
    Overall Length: 7.9 in.
    Threads: 1/2 in. – 28 tpi
    Attachment Type: Direct Thread
    Material: Titanium & Stainless Steel
    MSRP: $745
    Manufacturer: SIG Sauer

  • billybob January 15, 2018, 3:13 pm

    SIZE IS EVERYTHING ! AWC MK9 is still the quietest 2\” by 12\”

  • Wayne January 3, 2018, 11:39 am

    Suppressed .45 are nothing new. I never fIred one but, saw different special forces and spooks carrying hush puppies in the nam.
    Guess they hushed dogs, geese and such with them

  • phil January 3, 2018, 9:57 am

    It is so quite, I am not going to give you any decibel reduction numbers. ?!!!??

  • Wayne January 2, 2018, 6:54 pm

    The early 16’s were a POS so most of us kept our 14’s, Nowadays they (14’s) are so much better and I even own a few but I still have and prefer my 14!! SFMF…

  • Keith January 2, 2018, 5:57 pm

    I am a fan of the AR-15 if you are shooting 6.5 x 39 Grendel, 6.8 x 43 or the .300 Blackout using supersonic 125 grain bullets. I never did care for 5.56 x 45 round. Most people shoot 5.56 with 55 grain bullets and they begin to lose a lot of effectiveness beyond at about 110 yards. Supersonic .300 Blackout from a 16 inch barrel using 125 grain or lower bullets is pretty effective to about 260 yards. 6.5 x 39 Grendel and 6.8 x 43 are very effective at 300 yards. All these rifle rounds can use a standard 5.56 receiver with the AR-15 upper assembly being changed out.

    • kyle January 3, 2018, 7:40 am

      What does this have to with anything?

  • Dennis January 1, 2018, 12:49 pm

    Another good article but your reference to the thread size is confusing.
    1/2 in x 28 tpi, (.500 in x 28 tpi) seams like a small diameter for a bullet that is .45 in. What is a .578 in x 28 tpi?
    That is somewhere between 9/16 in and 5/8 in.
    Am I missing something?

    • Wzrd January 1, 2018, 7:32 pm

      1/2-28 tpi is American standard for most 22 caliber rifle barrels & also 9mm pistol barrels & some pcc barrels. .578-28 is American standard for most .45 ACP pistol barrels.

  • Eugene Kaptur January 1, 2018, 6:31 am

    For two consecutive years I carried a M3A1 sub-machinegun, i.e., “greasegun” with an Ithica silencer…at least that’s what they were called back then. I also had another without the silencer. Usually no matter if humping the jungle or flying from hilltop to hilltop picking up my prisoners to Interrogate….YES, I had a fancy title of Province Interrogation Advisor, but in reality I was just the only American Interrogator in Quang Tien Province and would pick up prisoners captured by PFs and others rather than them shooting them. Anyway that combination, for where I was located, rice paddies and double canopy, was an awesome weapon which was accurate enough to shoot at least 200 yards, but powerful enough to be a real “brush cutter” in double canopy jungle. Usually what one heard when I fired was just a low rumble and that 2 pound bolt slamming back and forth. With the Ithica it balanced out the weapon so I had virtually no muzzle rise as long as I didn’t fire more than about 6 round bursts, which I usually didn’t. The silencer was somewhat difficult to clean though, with it’s steel and bronze washers and stainless steel springs, but that was not a daily affair. What I can really say is that my weapon NEVER failed to fire, dirty, wet, muddy, rusty….it always fired as long as I used good mags. My basic load was carried in a captured NVA magazine carrier holding 9 x 30 round mags and one in the weapon for a total of 300 .45 caliber rounds! Heavy YES, but far more reliable that the JUNK M-16s that our troops were armed with which could only fire 18 rounds out of a 20 round mag or they would fail to feed….of course that was not taking into account their many other failings! Interrogated hundreds of prisoners shot with the M-16 who survived, never managed to talk to one shot with a .45!

    • American USMC January 1, 2018, 11:03 am

      I’m a fan of the M3 “grease gun” or M3A1 also of the .45acp. I even like the the M-16. Shot one with out cleaning for over 5000 yes 5000 rounds and not one jam or mis fire. The M 16 started to slow down after 5000 rounds ,but I wiped the bolt and carrier off and good to go.My view is that the M16 is not junk and the .223 will chew up anything you shoot with it.

      • Eugene Kaptur January 2, 2018, 11:12 pm

        One night after a firefight with NVA, about 10 miles West of the Hai Van Pass North of Da Nang, the Company Commander of K/3/1 was checking the area around the company I was attached to for that Operation and said “what in the hell are you firing?” in reference to the tunnels that I had cut in the double canopy during the firefight the previous night. I showed him my grease gun and he said “from now on you sleep by me!”….most of the M-16 5.56mm rounds hit that double canopy and didn’t penetrate very far, a very ineffective weapon for that type of fighting!

    • kyle January 3, 2018, 7:45 am

      Too bad they loaded 5.56 with the most useless projectile they could have possibly used.

    • Timm Heisey December 9, 2018, 8:47 pm

      Thanks for sharing!

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