subsonic 223 rem


July 8, 2005, 11:45 PM
i was cruising around accuratepowder's website looking at their OAL for .223 and just happened to notice at the very bottom of their page (

that they list 3 subsonic loads!

now, i just happen to have several pounds of s1250, and a bungload of 55fmj, but before i do anything really stupid, can i get a sanity check here?

they really are recommending 3.5 grains of a shotgun/pistol powder for a .223 Rem, at a pressure of 13500, right?

anybody ever try this before?

and yes, i realize it won't cycle in my ARs

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July 9, 2005, 10:15 AM
Not in the 223, but, I load my 7mm-08, 30-06, 300WSM and 7.62x39 with Blue Dot (Shotgun powder) for low recoil loads. I found out about Blue Dot light loads here
They are very, very accurate and fun to shoot. I have tried other reduced loads with various powders and nothing even came close the the accuracy of the Blue Dot.

I am not sure but, I thought I saw the Blue Dot boys over at accurateloading discussing the 223. Check it out.

July 9, 2005, 02:43 PM
I can't get that page to work, but yes I have tried very slow 223 loads. The rifle I used had a "normal" twist and would not stablize 55 FMJ bullets. Every one hit the 25 yard target sideways. But I did get 40 grain bullets down to 22LR velocities. Never went subsonic, but at about 1300 FPS I was getting good groups at the spot where the crosshair widened on the bottom of the duplex reticle. I don't remeber if it was Red Dot or Bullseye, but I got the load from the Lyman manual. I used it for squirrels and rabbits.

Be careful of stuck bullets.

Zak Smith
August 9, 2005, 11:40 AM
Subsonic 223--

55gr flat base SP
3.0 - 4.0gr UNIQUE, depends on barrel and local environment
LC brass, WSR primer

Follow all prudent safety measures. These loads appear stable in 1:7.7 and 1:9 barrels.

I've found some references on the web through Google which refer to using faster powders for the 50-55gr bullets, such as Clays, N310, etc, but haven't tried any.


Major Beer
August 10, 2005, 12:09 AM
why would you want a subsonic .223?

is that a hi power 10/22 or something - just curious?

Zak Smith
August 10, 2005, 12:16 AM
Yeah, you can get the same power and effect in 22LR, but if you if you have a 223/556 suppressor, subsonic 223 loads start to make sense-- ( [ link to LARGER image ] (

August 10, 2005, 08:23 AM
Slower velocities will require a faster twist for stability.
Which is exacerbated by the need for the heaviest bullet possible in order to maintain higher power levels as such low velocities.

Dave R
August 10, 2005, 08:52 PM
So, if I try these in my 1:12 NEF Handi-rifle, I'm prolly gonna get keyholing, eh?

August 10, 2005, 08:57 PM
try what? 55g? i wouldn't expect any keyholing

Zak Smith
August 10, 2005, 09:07 PM
Don't 22LR rifles have twist in the range of 1:14 to 1:16? Most 223's are from 1:7 to 1:12.

If you are getting keyholing with a certain bullet, here's what you can do:

1. choose a short & blunt bullet, like a soft-point flat-base. This decreases the transverse drag force (ie, the one trying to push the nose over the base) and increases the axial moment by putting more of the mass further from the axis.

2. go down one bullet weight (ie, 55 to 50, then to 45 or 40, etc)

Dave R
August 10, 2005, 11:20 PM
Good! I have some stubby 45 grainers. This should be fun...

Zak Smith
August 10, 2005, 11:45 PM
Well, you won't know until you try, and as long as you don't have a suppressor attached, there's no harm from tumbling bullets in experiments. Just make sure you don't get a bullet stuck in the barrel. Either account for each target impact, or visually inspect the bore.

August 11, 2005, 03:21 AM
Slower velocities will require a faster twist for stability

So is that why my .17 Rem has a 1:9" twist and my .45 ACP has a 1:18.5" twist?

As to the original topic, loading the .223 to sub sonic velocities is going to have some negative ramifications due to % used of case capacity. When you start to load down below 80% of volumetric capacity, you start to run into accuracy problems and erratic pressures, hence erratic velocities. Below 50%, and ignition reliability becomes a problem becasue the primer is sending it's flash over the charge instead of into it.

August 11, 2005, 08:12 AM
So is that why my .17 Rem has a 1:9" twist and my .45 ACP has a 1:18.5" twist? No.

The rate of twist is based on the size of the bullet not it's weight.
It is the ratio of bullet length to bullet diameter.
However, for a given diameter, a heavier bullet is usually longer than a lighter bullet.

In 1879 Sir Alfred George Greenhill developed the Greenhill Formula for Rifling Twist to determine necessary rates of twist for artillery pieces.

Greenhill’s original formula originally stated;
The twist required in calibers, equals 150 divided by the length of the bullet in calibers.
(Expressing projectile length in Calibers is an old artillery practice.)
Today we express bullet length in inches or milimeters.

Another problem with Greenhill’s original formula was that it was designed around heavy, round projectiles moving within a small window of velocities.
The value of 150 used by Greenhill was based on spherical, pure lead projectiles launched with black powder.

So in order to take in account modern bullet designs and small arms bore diameters a modified Greenhill formula is used.

The modified (simpler) formula is;
T = Q × D²÷L
(Twist equals Velocity Value times Bullet Diameter squared, divided by Bullet Length)

D = bullet diameter in inches
L= bullet length in inches
Q = a range of velocity “value”
T = rate of rifling Twist

Values for velocity ranges are;
Below 1000fps - 45
1000-1499fps - 125
1500-2999fps - 150
3000-4500fps - 180

Now this is all well and good and for the most part will get you into the ball park but it doesn't take into consideration the wider range of velocities obtainable with today's propellants nor does it allow for the various alloys and materials used in modern bullet construction.

So, we come to the Sierra Bullet Company formula.
Actually it's formulae, since Sierra uses a different formula each for rifles and handguns and they are based on velocity whereas the original Greenhill formula was based on specific gravity.

The Sierra formula for Rifles is T = 0.06 × V × D² ÷ L

The Sierra formula for Handguns is T = 0.05 × V × D² ÷ L

D = bullet diameter in inches
L = bullet length in inches
V = velocity in feet per second
T = rate of rifling Twist

So you see the two disiplines seldom agree but each one will get you close to the twist needed for reliable stabilization.

I prefer the Sierra method because you can calculate the necessary rate of twist based on the down range velocity of the bullet.
It will tell you at what range the bullet is likely to become unstable.

All of the above helps illustrate why, when firing a heavier and or slower bullet you need a faster rate of spin for stability.
And why a 180gr Barnes all copper bullet can use a slower rate of twist than a 180gr pure lead bullet.
Or why a .454 Casull firing a hard cast SWC needs a faster twist than a Colt 1860 Army firing a pure lead round ball.

Zak Smith
August 11, 2005, 12:20 PM
Below 50%, and ignition reliability becomes a problem becasue the primer is sending it's flash over the charge instead of into it.
This is possible, but not necessary. People are getting extreme spreads (ES) of less than 25fps.

Dave R
August 11, 2005, 07:08 PM
When you start to load down below 80% of volumetric capacity, you start to run into accuracy problems and erratic pressures, hence erratic velocities. I think that's why fast pistol powders are used in lite loads. They are much easier to ignite, and less sensitive to case position.

I have also heard warnings against using some rifle powders, especially slower powders, in lite loads, as there is a risk of explosive detonation.

FYI I once posted a lite load I was using for .308 (down to about .30-30 levels) using H335. Bruce Hodgdon happened to read the post and warned me about that powder choice, and recommended a switch to H4198 because it was faster and easier to ignite.

December 21, 2005, 12:01 PM
I just got back from the range and I thought I'd share my experience with subsonic 223.
I loaded HP38 in Winchester cases with CCI primers and Winchester 55gr projectiles. I chrono'd them at about 15 feet. Rifle was an AR-15 with a 16" barrel 1/9 twist.

HP38 4.0 grains, four rounds fired
1246 fps
1230 fps
1231 fps
1229 fps
No problems, but not quite subsonic

HP38 3.5 grains, 4 rounds fired
1100 fps
1066 fps
1042 fps
1110 fps

The 3.5 grain load grouped about half an inch (6 rounds at 15 yards offhand), no keyholes

The rifle did not explode,and, obviously, did not cycle. Primers showed no signs of overpressure. Happy shooting.

May 28, 2006, 11:49 AM
Has anyone played around with much heavier bullets like the 77 grain SMK ? Especially with any of the more commonly available powders. That link in the first post lists some loads for heavy bullets, but I dont' have that powder.

Let's look at that "Sierra" formula:
The Sierra formula for Rifles is T = 0.06 × V × D² ÷ L
D = .224" (bullet diameter in inches)
L= .984" (bullet length in inches)
V = 1050 fps (a range of velocity “value”)
T = rate of rifling Twist

I get an answer of 3.21 is this correct ? I am barely literate.

Let me cut to the chase here: If I loaded a 77 grain SMK with the dimensions above, to the velocity listed above and fired them out of a 1:7 , 16" AR15 barrel, would the bullet be stable or would the bullet strike the baffles in my suppressor ?

May 28, 2006, 07:43 PM
I had a friend plug some data into the computer software "Quick Load". This is a load he came up with that I would like to hear some comment on. I guess if I don't get any response today, I will call Hodgdon on Tuesday. I always want something like this when the business isn't open.

16 " barrel
2.26 OAL
77 grain Sierra Match King bullet
8.0 grains of H4895 powder
Should give me 1011 fps at 7671 psi of pressure.

This sounds like a great load. The loading density was over 30% case capacity. He had to go before I could get the exact number.
Is this powder safe to load with reduced loads like this ?

FWIW, when he plugged in 3.0-4.0 grains of Unique into the program it said it was over pressure, but I wasn't there to make sure he was doing everything right. :confused:

May 28, 2006, 09:17 PM
I just loaded 20 of these.
Talk about tedious.
Obviously, I had to trickle each charge.
Testing will begin either tomorrow or Tuesday.

Dave R
May 30, 2006, 01:45 PM
I tested some of these loads yeasterday:

-Milsurp brass
-4.5gr of Unique, and 4.0 gr. of Unique
-53gr Sierra Match Hollowpoint bullet (I had a half-box of these I wanted to use up)
-CCI Small Rifle Magnum primer

Velocity with 4.5gr of Unique averaged 1340fps
Velocity with 4.0gr of Unique averaged 1140fps

Test rifle was an NEF Ultra-Varmit with 24" bull barrel.

Good news:
-No bullets stuck in the bore! As you can see, velocity was satisfactory.
-Accuracy was very good. I shot only at 30 yards (in the desert, plinking). Both loads shot into nearly the same hole at 30 yards.

Bad news: POI was about 4" below POA. I suppose I should've expected that, going with the scope zeroed for a 3,200 fps load at 100 yards, vs, shooting at 1,100 fps at 30 yards. I was hoping to find a range where POI and POA matched, with my existing zero. I didn't have enough time to check other distances. But starting 4" low at 30 yards, I don't think the bullet was still "climbing", so I doubt I'll find a good distance where I can use the existing zero.

Noise was about the same as a .22 LR.

So, I essentially created a .22LR out of my .223. Now that I've done it, I don't see a use...

May 31, 2006, 01:45 AM
So, I essentially created a .22LR out of my .223. Now that I've done it, I don't see a use...

Well why not have a few loaded up for "survival" use? Would be great for rabbit or squirrel or other small game. Or for use against small pests.

To me it's sorta like having an extra attachment in the tool box.

Dave R
May 31, 2006, 11:03 AM
If I could find a load that would let me keep my long-range zero, and have POA=POI at some shorter distance, I could see a use. Maybe I just need to experiment more. I was assuming that, if my impact was 4" below POA at 30 yards, I wasn't going to find one.

June 1, 2006, 08:54 PM
If a .22LR shoots a 53 grain boat tailed jacketed hollow point at 1340 fps, then I guess you did make your .223 into a .22 LR.

Ok, back to our regularly scheduled programming.
As you all see, I didn't get any comment or advice on the load I posted, however I went out and tested it anyway.
As I posted, this load was supposed to give me 1011 fps out of a 16" barrel.
It didn't.
I shot 24 of these through the chrono. The first eight were just randomly loaded and gave me a velocity of 1394 fps. The second eight were all fired after holding the muzzle vertical and tapping the stock three times prior to firing. This was to see if the minimal powder charge would ignite differently inside the case because of the positon of the powder in the case. Anyway, the second eight rounds gave me an average velocity of 1342 fps. The third eight were fired after holding the rifle muzzle down and tapping the stock three times prior to firing. I got a muzzle velocity of 1287 fps.
Oh, one thing I forgot to mention: the first series of eight were fired without a suppressor and the second and third groups of eight were fired with a suppressor.
The action did not even attempt to cycle on an AR15 with these loads.
They exhibited decent accuracy: I shot some on paper but didn't really attempt to shoot the best possible group. I was mainly shooting the first dozen or so to see if I got any keyholing prior to shooting them through my suppressor (keyholing = baffle strikes). Point of impact was very close to my 200 yard zero.

So, I definitely didn't recreate a .22LR using my AR15. I was shooting a 77 grain jacketed boattail hollowpoint bullet at approx. 1300 fps. That bullet is very close to twice as heavy as a .22 LR solid.
For many years, spec-ops type people have used suppressed .22 handguns for various purposes, one of which we have to assume was to shoot humans. As an example, when the U2 pilot Francis Gary Powers was shot down over Russia during the cold war, he was carrying an integrally suppressed High Standard .22 pistol which is now on display in Red Square. We know that various people during the Vietnam war used similar pistols and it stands to reason that the military and covert people are using similar weapons today. What is the point ? Well, an integrally suppressed .22 handgun is shooting a 40 grain (or less) lead bullet at less than 800 fps.............BUT, very highly trained people chose that weapon for use against other humans. Granted, this was not a weapon chosen for general combat. I am sure they envisioned it to be used at close range against targets that were totally unaware that they were going to be shot at, so precise surgical shots could be used. These light .223 loads would easily outperform these .22s by a wide margin.

I am trying to find a load that will propel a 77 grain Sierra Match King at a velocity just under the speed of sound. In all likelyhood I will simply use this load to screw around with and to demonstrate how quiet my suppressor is. But, in the fantasy land of SHTF, I think it would be nice to have one magazine in that special pouch, of these subsonic loads for silently taking small game, poaching, or if need be, taking out an enemy. I am sure the load would be up to it if the conditions were right.

June 1, 2006, 10:32 PM
As you all see, I didn't get any comment or advice on the load I posted, however I went out and tested it anyway.

that shouldn't be construed as lack of interest. we just didn't have anythign intelligent to add :)

June 1, 2006, 11:19 PM
I guess I forgot the spreads:
Randomly loaded was 133 fps.
Muzzle up was 98 fps.
Muzzle down was 81 fps.

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