Subsonic .223 loading

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Jer
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Subsonic .223 loading

Post by Jer » Sun Oct 13, 2013 11:25 am

I've been tinkering over the past few weeks trying to use different powders and loads to create the perfect (for me) subsonic .223
So, after another full day of experimenting, I've landed with the best recipe I can make for a 55 grain round and my weapon platform. YMMV....
Here is a general step-by-step on making subsonic .223 ammo:

Everything needed to create a subsonic 55 grain round that will deliver 128 ft/lb energy at 1000 FT/s
Bullets, casings, scale, sharpie, cotton balls, punch tool, Trail Boss powder

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As you can see, the Trail Boss powder is seriously huge. It's primary design is for Cowboy Action type firearms - but it's large signature and fast burn rate make it an exceptional choice for creating subsonic .223 or even subsonic .308 ammo.
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Everyone's weapon is different so don't use this recipe and expect the exact same results. This was tested and dialed in on an AR-15, 16" barrel, 1:8 twist, mid-length gas system, with a YHM Phantom Suppressor.
The cases were trimmed to 1.743" and the Over All Length (with seated bullet) is 2.220" using a Speer 55 grain HPBT projectile.
3.8 grains of the IMR Trail Boss powder is what I fine tuned. This gives me 1005 FT/s at 123 ft-lbs of energy. (In comparison a 40 grain .22lr round at 1000 FT/s is 88.8 ft-lbs)
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After charging your primed case with the 3.8 grains of powder, rip off a tiny piece of cotton from a cotton ball - (quarter shown for size comparison.)
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Stretch out the cotton so that it looks like a bad Halloween spider web - very wispy and airy.
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Using your punch tool, gently push the wispy cotton into the case. This will keep the 3.8 grains of powder over the primer hole ensuring full ignition of the powder when the primer is struck.
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Couldn't get a great photo, but the cotton should fully cover the primer and be significantly lower than the bullet base when seated.
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After seating and crimping the bullet in the normal fashion, take a black sharpie and color the tip of the round black so you don't get them confused with your super-sonic ammunition. And now you have a subsonic .223 that can be whisper quite and still take down game out to 100 yards.
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Remember, this is a 55 grain projectile at 1005 FT/s delivering 123 ft-lbs of energy. With proper shot placement (all shots should be properly placed) you CAN take down deer sized game out to 100 yards with this round. In a true SHTF scenario, this could be a life saver if you need to kill your food silently without alerting those zombies around you as to your location. I feel this is a very useful load to have and I'd be very interested in seeing what others came up with in regards to .223 subsonics.

I have not yet tested my grouping at 50 and 100 yards with this recipe as I am waiting for new scope rings. But once I have, I will post my groups.
Those who make peaceful revolution impossible will make violent revolution inevitable.
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Blackthorn-USA
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Re: Subsonic .223 loading

Post by Blackthorn-USA » Mon Oct 14, 2013 3:43 pm

Very cool tutorial! It's interesting to me as I am just getting into the reloading game. My K-2 loves 55g ammo too so double win :)
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Jer
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Re: Subsonic .223 loading

Post by Jer » Tue Oct 15, 2013 5:41 pm

Test shot from my first batch of subsonic .223 hand loads.
They are FREAKY quiet with the suppressor. It's hard as hell to take a video while shooting so sorry for the shakiness of the video. Look at the small brush pile. Bullet impact is just below and slightly to the left of the pile. UBER quiet!! And yes, I'm shooting off of my upper deck. :) Gotta love a silenced weapon!!

Those who make peaceful revolution impossible will make violent revolution inevitable.
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Pete
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Re: Subsonic .223 loading

Post by Pete » Sun Nov 17, 2013 7:03 pm

why 55g you are limited by 1000fps not bullet wieght a 77g would be more lethal and most match grade bullets have a thin jacket, to thin for standard velocity loads but may open subsonic

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Jer
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Re: Subsonic .223 loading

Post by Jer » Wed Oct 08, 2014 12:31 pm

Pete wrote:why 55g you are limited by 1000fps not bullet wieght a 77g would be more lethal and most match grade bullets have a thin jacket, to thin for standard velocity loads but may open subsonic
It's what I had on hand at the time. I wanted to develop recipes for all different weights. Today, I've tossed together a video on how I make the subsonic in 69 grains. It's a fairly terrible video and I'll make a better one later, but the information is in there:

Click here for the video
Those who make peaceful revolution impossible will make violent revolution inevitable.
--John F. Kennedy

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Jer
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Re: Subsonic .223 loading

Post by Jer » Sun Oct 12, 2014 1:24 pm

I wanted to look further into the differences between using and not using a cotton filler.

So, here is what I learned today.

I created two batches. Matched brass.
Batch 1 was using a 69gr Sierra Match King #1380 with 4.6 grains of Trail Boss and cotton filler
Batch 2 was using a 69gr Sierra Match King #1380 with 4.6 grains of Trail Boss and NO cotton filler

BATCH 1
Created: 12/10/14 01:02 PM
Description: 4.6gr Trailboss w/Cotton
Notes 1: Sierra 0.224 HPBT MatchK 1380 69 0
Distance to Chrono(FT): 5.00
Ballistic Coefficient: 0.296
Bullet Weight(gr): 69.00
Temp: 55 °F
BP: 30.15 inHg
Shots:
# FPS / FT-LBS
9 1005 / 155
8 1008 / 156
7 1032 / 163
6 994 / 151
5 1026 / 161
4 1032 / 163
3 1056 / 171
2 1028 / 162
1 1002 / 154
Average: 1020.3 FPS
SD: 19.5 FPS
Min: 994 FPS
Max: 1056 FPS
Spread: 62 FPS
Shot/sec: 0.2
True MV: 1022 FPS
Group Size (in): 0.00


BATCH 2
Created: 12/10/14 02:01 PM
Description: 4.6gr Trail Boss - no cotton
Notes 1: Sierra 0.224 HPBT MatchK 1380 69 0
Distance to Chrono(FT): 5.00
Ballistic Coefficient: 0.296
Bullet Weight(gr): 69.00
Temp: 55 °F
BP: 30.15 inHg
Shots:
# FPS / FT-LBS
11 1034 / 164
10 1092 / 183
9 1059 / 172
8 1083 / 180
7 1068 / 175
6 1292 / 256
5 1274 / 249
4 1115 / 191
3 1025 / 161
2 1124 / 194
1 1017 / 158
Average: 1107.5 FPS
SD: 93.4 FPS
Min: 1017 FPS
Max: 1292 FPS
Spread: 275 FPS
Shot/sec: 0.1
True MV: 1109 FPS
Group Size (in): 0.00


As you can see, the standard deviation on Batch 1 (with the cotton) was a fairly outstanding 19.5 with a spread of 62 while the standard deviation on Batch 2 was a fairly terrible 93.4 with a horrific spread of 275.

While I find it a bit odd, and worth more testing to confirm, that the absence of the cotton filler would cause higher velocities (due to slower burn and higher pressure possibly) I do think this is significant enough data at the moment to validate the use of a filler in the case and to counter any argument that says Trail Boss is a non-positional sensitive powder...it sure appears to be VERY sensitive at this point.

Note: I did have 2 rounds not read by the chrony in batch 1. However, if they were even remotely close the rest, the spread and SD wouldn't have changed much - and no guarantee it would have worsened.
Those who make peaceful revolution impossible will make violent revolution inevitable.
--John F. Kennedy

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