Minimum suppressor length by caliber

jimbobborg · Aug 4, 2015

Is there a chart or something that has a minimum length of suppressor by caliber and barrel length? For instance, if I'm running a 10" rifle in .223, what would be the shortest length of suppressor you would need to be hearing safe? Would a longer barrel require a shorter suppressor? If I wanted to do the same thing with a 8" 9mm rifle, what length would the shortest can have to be to be hearing safe? I'm still trying to convince myself to get one or two, just need some more info to push me over the edge. Thanks.

Ranb · Aug 4, 2015

I don't think any commercially made silencer will make a 223 sbr hearing safe unless it was using subsonic ammo. The shorter barrel just lets out much more noise; the gas temp and pressure are much higher at the muzzle of a 10" barrel compared to a 16 or 20 inch barrel.

In my own opinion noise level and the amount of suppression required also depends upon gas volume and pressure.

I've shot a very nice 147 grain subsonic 9mm sbr with a six inch barrel that was entirely hearing safe with a silencer. The same setup with 26 grains of powder pushing a bullet +2800 fps would have been much noisier.

I've never seen a chart like you hope exists. It would be nice though. All silencers are a compromise between bulk, weight, price and suppression.

Ranb

Klunatic · Aug 4, 2015

I have never heard of a chart that relates barrel length to suppressor length. I honestly don't think the barrel length has much if any impact on the ability of a suppressor to reduce the report of the rifle. The volume of the suppressor and design of the baffles is what will determine the level of suppression. I have shot my .223 with my AAC 762SDN-6 and it is "hearing safe" with a 16" barrel. Hearing safe being below 140 DB for impulse noises. I have shot my 300 BLK supersonic with the 762SDN-6 out of 16", 12.2" and 10.2" barrel and there is no discernible difference in report averaging at about 130db. You will most certainly be ok with a 8" 9mm suppressed. First of all it will be subsonic and most suppressors will easily get you in the 126-130 DB range.

Butcher · Aug 7, 2015

Shot my 11.5" sbr ar-15 with my gemtech G5 outside and it was hearing safe. Probably wouldn't shoot any of my rifles with it indoors though

Biggfoot44 · Aug 7, 2015

Bbl length has an effect, as it relates to remaining gas pressure as the bullet exits the muzzle. It will vary somewhat depending on the exact loading and pressure curve.

But there is no set formulat for "length" of the supressor required. It will vary greatly with the baffle design , and internal volume. ( hint diameter matters too.)

outrider58 · Aug 7, 2015

5.56 10.5" SBR through my Surefire 556 Sodom is hearing safe out doors. No such thing as subsonic 5.56-.223 round for AR platform. It won't cycle.

teratos · Aug 7, 2015

Volume is one part of the equation. As you know, the baffle configuration can be a factor, too.

daNattyFatty · Aug 7, 2015

outrider58 said:
5.56 10.5" SBR through my Surefire 556 Sodom is hearing safe out doors. No such thing as subsonic 5.56-.223 round for AR platform. It won't cycle.

Dang dude, what else could you possibly be suppressing????

SWO Daddy · Aug 7, 2015

jimbobborg said:
Is there a chart or something that has a minimum length of suppressor by caliber and barrel length? For instance, if I'm running a 10" rifle in .223, what would be the shortest length of suppressor you would need to be hearing safe? Would a longer barrel require a shorter suppressor? If I wanted to do the same thing with a 8" 9mm rifle, what length would the shortest can have to be to be hearing safe? I'm still trying to convince myself to get one or two, just need some more info to push me over the edge. Thanks.

There are other far more important variables than length.

rsideout · Aug 7, 2015

outrider58 said:
No such thing as subsonic 5.56-.223 round for AR platform. It won't cycle.

Yes there is subsonic 5.56 ammo, I've got a box. This stuff is pellet gun quite with a good can.

And there are AR uppers that are specifically set up to cycle with subsonic 5.56 ammo. Check out Beck Defense.

smokey · Aug 7, 2015

...."that's what she said" opportunities abound in this thread.

outrider58 · Aug 7, 2015

daNattyFatty said:
Dang dude, what else could you possibly be suppressing????

cuffing auto correct! :lol:

outrider58 · Aug 7, 2015

rsideout said:
Yes there is subsonic 5.56 ammo. This stuff is pellet gun quite with a good can.

And there are AR uppers that are specifically set up to cycle with subsonic 5.56 ammo. Check out Beck Defense.

https://www.youtube.com/watch?v=hz6MX7thu2o

You, I consider an expert on this subject but, I was referring to generic rounds and generic rifles. I am here to learn.

rsideout · Aug 7, 2015

outrider58 said:
You, I consider an expert on this subject but, I was referring to generic rounds and generic rifles. I am here to learn.

Thanks. Not really an "expert", but I have tried out quite a few different cans on numerous platforms. :innocent0

. Subsonic 5.56 is the ballistic equivalent of a .22LR.....that costs over $1.00 per round. I consider it more of a novelty.

Wfilardo · Aug 8, 2015

+1. Whats the point of shooter a 65 grain bullet subsonic. Might as well shoot 22LR.

Ranb · Aug 9, 2015

rsideout said:
Thanks. Not really an "expert", but I have tried out quite a few different cans on numerous platforms. . Subsonic 5.56 is the ballistic equivalent of a .22LR.....that costs over $1.00 per round. I consider it more of a novelty.

Subsonic 223 is never the ballistic equivalent of the 22lr unless they start making jacketed 22lr bullets with weights at least 70 grains. I'm very proficient at reloading subsonic ammo and (less so) at using a simple calculator. Loading ammo for a 223 is a rather "generic" procedure that anyone can do.

Wfilardo said:
+1. Whats the point of shooter a 65 grain bullet subsonic. Might as well shoot 22LR.

Some data for you;

CCI Std vel 40 grain at 1060 fps is 100 ft-lbs
SSS 60 grain at 750 fps is 75 ft-lbs
55 grain fmj at 1050 fps is 135 ft-lbs
62 grain M855 at 1050 fps is 152 ft-lbs
70 grain at 1050 fps is 171 ft-lbs

With a 100 yard zero the CCI rimfire is only going to be 2" lower (at 39") than the higher BC centerfire cartridges, but the most important feature is going to be the 30-70 percent higher power. That is the point.

I'm paying about $65 for a brick of good CCI or SK target ammo. 500 rounds of subsonic 223 costs me $71 to $82 to reload depending on the cost of components.

Ranb

rsideout · Aug 9, 2015

I was talking more along the lines of a full powered .22 LR at about 1250 FPS. With a 40 grain bullet, they're around 140 ft-lbs.

And that sounds like a great price to reload your own subsonic .223.

outrider58 · Aug 9, 2015

Ranb said:
Subsonic 223 is never the ballistic equivalent of the 22lr unless they start making jacketed 22lr bullets with weights at least 70 grains. I'm very proficient at reloading subsonic ammo and (less so) at using a simple calculator. Loading ammo for a 223 is a rather "generic" procedure that anyone can do.

Care to offer any recipes?

Ranb · Aug 9, 2015

rsideout said:
I was talking more along the lines of a full powered .22 LR at about 1250 FPS. With a 40 grain bullet, they're around 140 ft-lbs.

Yes, but comparing a supersonic load to a subsonic load is apples and oranges. In my opinion any suppressed supersonic 22lr is much louder than a suppressed subsonic 223. I only shoot suppressed these days except for shotgun (until I make a can for it), 3P rifle, revolvers and black powder.

There is also the problem of the high drag 40 grain bullet going transonic about 50 yards downrange and degrading accuracy. I learned long ago that if I want to hit a small target with a 22lr past 75 yards, then I need decent subsonic ammo like CCI Std Vel or better.

And that sounds like a great price to reload your own subsonic .223.

It is a decent price. Everything I shoot is reloads other than 22lr, 12 gauge, 7.62x39 and 7.52x54.

For a Mossberg MVP, 1-9 twist it is a 55 fmj with 3 grains of Bullseye. My brother wants cheap ammo, so he uses the bulk bullets.

For my NM AR-15, 1-8 twist I use the Speer 70 grain bullet with 7 grains of H110 or 3.5 grains of Bullseye.

The cartridges are loaded to the crimping groove for the fmj, to 2.26" for the 70 grain bullets. No filler is used. Magnum primers are better than standard as they are more consistent. Use of a chronograph is not optional, it is required to ensure that you are at least 1000 fps so the bullet doesn't yaw and cause baffle strikes and less than 1100 fps so you are not supersonic on a hot day. I load to 1050 fps so that I'm good to go with any temps you might see in the continental USA.

I always use mag primers for any subsonic load requiring large rifle primers like 308. Standard small rifle primers work very well on little cases like 300 blackout or the 223.

My subsonic 223 does not of course cycle the bolt on the AR-15. I'm thinking of making an upper with the gas port about 3" downstream of the chamber (like the 300 blk) so that the pressure is high enough to cycle with a 7 grain load of H110.

Ranb

Ranb · Aug 9, 2015

rsideout said:
And there are AR uppers that are specifically set up to cycle with subsonic 5.56 ammo. Check out Beck Defense.

Interesting video. Too bad the ammo required to make it run is not available, not even on their website.

Ranb

Minimum suppressor length by caliber

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