Subsonic 223/5.56

[offthepaper]

Does anyonehave any load data for subsonic223/5.56?
I'm looking to quiet it down as much as possible.

 

[Wildfire]

I know some guys that mess with .308 that way. But, I have not seen anyone try it with .223....
I do know they used only lead bullets and not jacketed. Slowest load I can find is a 45 grain cast bullet and it is still at over 1700 fps. You need under 1100 to shut off the crack. They also used shorter barreled bolt guns.

 

[ATCDoktor]

Hodgdon lists 4.0 grains of Trailboss on their on line Data Center as a subsonic load for 55 grain projectiles.

http://www.hodgdonreloading.com/

I have used this load with suppressed bolt actions and (depending on projectile and barrel length) it is subsonic.

It may take some tweaking to get the speed to where you want it as a tenth of grain one way or the other can mean the difference in breaking the sound barrier with Trailboss in the 223.

The Trailboss load notwithstanding, my favorite subsonic 223/5.56 load is 3.5 grains of Blue Dot and a Hornady 55 grain Flat Based JSP.

Its an accurate and consistent load in all my rifles and runs 950-1000 FPS (depending on barrel length).

When it comes to working up subsonic loads in this caliber, it has been my experience that boat tailed bullets are not the best projectiles to run at subsonic speeds.

Irrespective of caliber (boat tailed bullets at subsonic speeds) tend to turn in flight and fly base first (depending on your rifles twist rate) at varying distances from the muzzle.

If your twist rate isn't optimized for subsonics, I'd stick with flat based bullets in this caliber (if you can).

You need to be careful when loading for subsonics in any rifle caliber in that you may end up with a bullet stuck in your barrel (especially with jacketed rifle bullets).

Always check your target or backstop for impacts while doing your load development for subsonic ammo in centerfire rifle calibers.

It is important to use a chronograph and "work down" to the speed you desire.

As with all loading data you get from the internet, use caution, these loads are safe in my rifles but may not be safe in yours and keep in mind, your use of this data will be at your own risk.

 

[orionengnr]

I'm kind of new to the subsonic/suppressed game (looking at buying my first, a can for a .300 BLK AR), so I am still reading and learning...

Just have to ask--why a subsonic 5.56? The 5.56 bullet's effectiveness is dependent upon high velocity...

Using that velocity and weight, what you have is pretty close to a .22LR, but at probably 5x the price (even reloading).

If using a suppressor, a rimfire can is ~$300, while a centerfire can is 2-3x that much. So the ammo is 5x the price, the can is 3x the price...

This is pretty much why the .300 BLK exists. (Okay, maybe one of the two primary reasons the .300 BLK exists.)

Again, don't take this wrong, but what am I missing here?

 

[ATCDoktor]

Just have to ask--why a subsonic 5.56? The 5.56 bullet's effectiveness is dependent upon high velocity...

Using that velocity and weight, what you have is pretty close to a .22LR, but at probably 5x the price (even reloading).

If using a suppressor, a rimfire can is ~$300, while a centerfire can is 2-3x that much. So the ammo is 5x the price, the can is 3x the price...

This is pretty much why the .300 BLK exists. (Okay, maybe one of the two primary reasons the .300 BLK exists.)

Again, don't take this wrong, but what am I missing here?

I think what you are missing is that (for a great many people) the option to add a new caliber and a suppressor just isn't there.

A shooter of limited means looking to get into suppressors is going to have to suppress what he or she already owns and if what they own is a 223/5.56 it would behoove them (in my mind) to be able to assemble subsonic ammo for that caliber (if they want the optimum of suppression in that caliber).

Certainly any suppressor suitable for the 223/5.56 can be used with 22 LR ammo but most savvy suppressor owners wouldn't want to gunk up a sealed rifle can with the filthy 22 ammo but that option exists. I have done it (on a limited basis) with no ill effects.

With regards to the effectiveness of subsonic 223/5.56 goes, that has everything to do with your target.

I mostly shoot targets with my subsonic 223/5.56 (in a semi urban environment).

A subsonic 55 grain bullet is a whole lot easier to stop in my backstop vice a 125/150/220 grain 300 blackout bullet at the same speed.

My neighbors might not be able to hear the rifle being fired but they would definitely hear bullets whizzing down range if I fail to catch one in my bullet trap.

As far as the cost of reloading subsonic 223/5.56 goes, I wont break anyone's heart by sharing what I paid for the components I'm using to load my ammo nowadays.

I know that what I paid for components 30 years ago has no bearing on what a new shooter can expect to pay here in the 21st century.

What I will share with you is the following pearl of wisdom (if you haven't already heard it) is that the days of reloading ammo to be save money are long gone, reloading here and for ever more will be about having ammo to shoot vice not having it at all (especially when we are one election/mass shooting away from more turmoil in the ammo market).

 

[Another_Kelley]

As far as 'why subs in a 5.56/223'.... I was driven down this road due to the increased inability to find sub sonic 22lr ammo over the last couple years. I've been using a suppressor rated for 22LR on my M77 chambered in 223 & blue dot subs pretty successfully for a while now... they shoot as well & often better than the 40gr CCI Sub ammo I like so much for my 77/22.

I'm able to load my subs in 223 for under .15 cents - with the bullet being an average of .07-.09, primer .03, powder .012 cents.... per round, far from "5x the cost of 22lr".

I will say that I own a handful of rifles chambered in 300blk, absolutely love the cartridge... but at no point did they deter me personally from wanting to shoot little 40gr projectiles at sub speeds from my 223, quietly. Never did I say to my self... "wait a minute, 220gr at 1000fps is WAY better than a measly 40gr projectile at 1000fps, so therefore this is silly".

There's always something bigger/faster/better, but sometimes you don't need to break out the sledge hammer when a little ball peen can do the job

 

[balderclev]

I load 55gr Hornady SP/C with 3.7gr Trailboss. I load the bullets backwards. The sound is slightly more than a subsonic 22lr.

 

[LiveLife]

Does anyone have any load data for subsonic 223/5.56?

I'm looking to quiet it down as much as possible.

I load 55gr Hornady SP/C with 3.7gr Trailboss. The sound is slightly more than a subsonic 22lr.

Since OP posted 5.56, are we talking about subsonic loads for AR?

If so, there needs to be enough pressure to work the gas system for reliable cycling.

I load the bullets backwards.

Haven't heard this before for rifle loads. We did talk about it for pistol loads (Yes, 9mm bullets loaded upside down looks funny but they did chamber from the magazine) - http://www.thehighroad.org/showthread.php?t=456919

 

[ATCDoktor]

Most jacketed centerfire rifle bullets for bottlenecked cartridges have a center of gravity well behind the midpoint between the bullet tip and its base.

Their center of gravity being towards the rear of the bullet they tend to turn and keyhole at varying distances from the muzzle at subsonic speeds (depending on the twist rate of the barrel).

This characteristic is somewhat exaggerated in boat tailed projectiles.

Some people who load centerfire subsonics will load the boatails backwards to keep them flying true.

In my experience, subsonic 150 grain 30 caliber FMJ's (loaded base to the rear) will keyhole at 50 yards out of a 1 in 10 twist barrel.

Turned backwards, the FMJBT's fly true from that same 1 in 10 twist barrel.

That identified, it has also been my experience that Flat Based Round Nosed Soft Points (loaded base to the rear) fly true out of that same barrel (at subsonic speeds).

 

[LiveLife]

Thanks. Learn something new everyday on THR.

So is there benefit to loading a rifle bullet backwards for reducing sound?

Or is it for expansion performance on target?

 

[Another_Kelley]

So is there benefit to loading a rifle bullet backwards for reducing sound?

I've read somewhere that the less arrow dynamic a projectile is, the more noise it makes traveling through the air.... but at sub sonic speeds, I believe the differences aren't noticeable enough to even mention.

However at super sonic speeds, I can absolutely hear a noticeable difference in flight noise between a suppressed .355 bullet and a .22 cal traveling at the same speed.

 

[ATCDoktor]

Base forward loading of boat tails is primarily to keep the bullet flying straight in barrels not specifically rifled for subsonic use.

In my experience they are no more quiet (loaded base forwards) than conventional loaded subsonics.

That said, I have not specifically measured them with a DB meter. To my ear, there is no difference in their sound from my suppressors.

With regards to expansion, I have never tested base forward loaded subsonic boat tails for their terminal effect on any medium.

I would expect that their terminal performance would be poor but I could be wrong.

 

[LiveLife]

Or is it for expansion performance on target?

With regards to expansion, I have never tested base forward loaded subsonic boat tails for their terminal effect on any medium.

I would expect that their terminal performance would be poor but I could be wrong.

I was thinking FMJ with open lead base loaded backwards.

Practically, I do not have a need for backwards loaded FMJ but maybe interested in doing some subsonic accuracy testing after retirement if I get bored.