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Old March 23, 2013, 08:26 PM   #1
fpchief
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subsonic rounds

Gents, Been along time since i have posted. I really appreciate all the help you guys have given me in the past. I want to venture into the realm of subsonic rounds. For no real purpose than just wanting to. I really can't find too much info on it. A few simple questions....1) is it as simple as getting enough powder to go down the pipe without having a squib? 2) As simple as not having too much to keep it below the barrier? 3) main worry with silencer is to make sure it stablizes out of the barrel?? Can i use mostly any powder? got loads of blc-2 and H-335...bunches of 62 grain bullets too (5.56)

thanks for any help
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Old March 23, 2013, 10:31 PM   #2
Jimro
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Subsonic rounds are generally a smaller charge of a faster powder under a heavier bullet.

Using BLC-2 or H335 you run the risk of a detonation trying to get subsonic with a 62gr pill out of a 223. Think pistol powder.

What type of firearm would you be trying to use subsonic 5.56 through?

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Old March 24, 2013, 08:21 AM   #3
fpchief
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folks are using them out of SBR's and regular ar's. mostly suppressed. That is exactly what i will be using it with. So maybe try some hp-38, bullseye, etc? I heard of some using i think it was Trail boss?? if i have that right...stuff on it on other forums, but this forum has always been very good,safe,conservative for me so i am coming to advice here...
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Old March 24, 2013, 08:29 AM   #4
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and it will NOT cycle the AR. Supposedly some commercial subsonic out there that will though.
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Old March 24, 2013, 08:44 AM   #5
JohnMoses
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I played around with Quickload with various pistol powders, and could not get a 'subsonic' load in a 223 case that had sufficient detonation base. There were some bluedot loads that gave impressive velocities for tiny powder charges, which would generate less gas and make the can work better. Mind you, I have no experience, and this internet musing has little actual value. I'm pretty certain any subsonic load will not function a semi auto.
If I had a can affixed to an AR, I would drop in a 22 conversion and get a brick of Agulia subsonic. The fast twist barrel would stabilize the 60 grain bullet, I think. (see above disclaimer)
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Old March 24, 2013, 09:13 AM   #6
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Some powders work better with reduced loads then others. I do a lot of shooting with cast bullets, a lot are subsonic.

The powder that fills more of the case is going to be better. Two of the best are Trail Boss and 5744. SR 7625 works well too.

4895 also works well, the Army used it squite a bit in reduced loads.

Also some cases lend themselves better to reduced loads do to the size of the case. For example you're going to get better results (lower velocities) with a 30-30 then an '06.

A lot depends on what you want to do with the load and how far the target is. All are going to make noise when you shoot them, Subsonic normal refers to being below the speed of sound. It doesn't have to be below the speed of sound at the muzzle as long as it is at the target.

Meaning you need to add a ballistic program with your reloading data.

Might just be better off going to a pistol cart. in a rifle such as 38/357, 44, or 45 for the short range targets.
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Old March 24, 2013, 09:22 AM   #7
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Try this method with trail boss.

http://www.imrpowder.com/PDF/Trail-Boss-data.pdf

You may need a heavier bullet to get down to the velocities you really want.

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Old March 24, 2013, 02:38 PM   #8
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fpchief,

I load my own subsonic 223 using surplus WC820 (like H110) although any pistol powder will do. The key is magnum pistol powders that burn fast and consistently. Use a magnum primer for better ignition. You need a chronograph. Start high and work your way down to the velocity you need to avoid getting a bullet stuck in the bore. 7 grains of WC820 works well with the Speer 70 grain bullet.

Round nose bullets are much more likely to remain stable than the longer FMJ or boat tail bullets, the BC does not matter as much when subsonic, they all suck as far as the rainbow trajectory is concerned when shooting past 100 yards. The Speer 70 grain bullet works just fine with a 1-9 twist subsonic. I would not use the heavier match grade bullets at subsonic speeds. Check for keyholing without the silencer attached. If your accuracy suppressed is worse than unsuppressed, then you are getting baffle strikes.

The speed of sound varies only with temperature so I load for 1050 fps to keep it subsonic when cold and to avoid bullet flight noise near sonic speeds caused by air flowing around the curved bullet.

An AR-15 in 223 will not cycle with subsonic loads unless the gas system was made for it. This means it has the gas port about 4-6 inches down from the chamber like a 300 whisper or 300 blackout does. Most people (like me) settle for cycling the bolt carrier for each shot.

You might be disappointed with subsonic 223 as a 70 grain bullet while much more powerful than any 22lr (subsonic or hypersonic) is rather weak compared to a subsonic 240 grain bullet from the 300 blackout.

Subsonic ammo is still loud, especially in a short barrel, so I only see it as a benefit when shooting with a silencer attached. The only time subsonic unsuppressed is not loud is something like 22CB in barrels 16" and greater or 22lr std vel in a much longer barrel.

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Last edited by Lark; March 24, 2013 at 02:46 PM.
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Old March 24, 2013, 07:54 PM   #9
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Good info.

The Hodgdon Data center has subsonic loads listed as well. They show .223 55gr bullet loads for Trail Boss, Titegroup, and Clays.

There is some 308 date too.
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Old March 24, 2013, 08:15 PM   #10
bigD01
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subsonic loads

try this link

http://www.jamescalhoon.com/tobee2.php
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Old November 3, 2013, 09:51 PM   #11
omnimedic
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.223 sub loads

fpchief-

Like you, I wanted to load a .223 subsonic, "just because". I consulted with a buddy who reloads and he gave me his formula: 4.5 grains of Trail Boss.

I loaded some up under a 65-grain Nosler, and the only sound you hear is the hammer striking the firing pin with a can. As I expected, they won't cycle the bolt.

Go over to the semi-auto forum to see how I'm going to experiment to solve this. It involves reducing the weight of the buffer and/or reducing the spring tension to match the reduced forces generated by a reduced load.

I'll post results of my experiment over there when I get them.
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