Loading Subsonic 308 Win - Seeking Advice

[Liberty97045]

I want to load subsonic for 308 and 223, I have done some research and found many different opinions and few recipes.

I did get some good tips:

• Use fast pistol powders to avoid Secondary Explosion Effect http://www.thehighroad.org/archive/index.php/t-564535.html
• Shoot first shots with suppressor off to avoid baffle strikes from unstabilized bullets.

My rifle is set up for the heavier bullets so it makes sense to take advantage of this. I was thinking 200 or even 220.

1. Does anyone have a recipe for me?
2. How much risk will I be taking if I work up my own loads? For example, if I took a subsonic recipe with a lighter bullet and substituted a heavier bullet.
3. If I roll my own, what are the do's and don'ts?

The 308 is the primary gun. Savage 10 FCP which has a 1:10 - 24" barrel - I will be using a 308 suppressor.

The 223 is secondary - 20" barrel with same suppressor

I found this for 308 and 223 using Trail Boss. The problem is they only have data for lighter bullets.
http://www.loaddata.com/articles/PDF/LD-36 Haviland LR.pdf

This one is Trail Boss or Red Dot
http://www.thefirearmsforum.com/threads/anybody-have-308-win-subsonic-load-data.39007/page-3

Read More

 

[FA9]

Check out the Hodgdon website

 

[ConcreteJungle]

this was an interesting read

http://www.loaddata.com/articles/PDF/LD-36 Haviland LR.pdf

 

[David J]

Trail Boss is temp sensitive. I use IMR 4198 in both 300 BLK and 458 SOCOM. The 300 BLK is loaded with a 220 gr rn. and the 458 is loaded with a 500 gr rn. why use a light bullet for sub sonic the heaver bullet gives better ballistics down range.

 

[rick benjamin]

According to the NOAA, Speed of sound in FPS
is dependent on the density of the air...
is dependent on the temperature of the air.
99 degrees Fahrenheit = 1158.39 Feet per second = Speed of Sound
95f = 1154.23
90f = 1149.02
85f = 1143.78
80f = 1138.52
75f = 1133.23
70f = 1127.92
65f = 1122.58
60f = 1117.22
55f = 1111.83
50f = 1106.42
45f = 1100.98
40f = 1095.51
35f = 1090.02
30 degrees Fahrenheit = 1084.49 Feet per second = Speed of Sound

No matter how careful you are with someone else's recipe,
You have no way to prove your results unless...You use a chronograph.

I own a Chrony F Chronograph, purchased in 1988, and a CED-M2 purchased this year.
I would not work-up a load without them.

 

[Certaindeaf]

Trail Boss is temp sensitive. I use IMR 4198 in both 300 BLK and 458 SOCOM. The 300 BLK is loaded with a 220 gr rn. and the 458 is loaded with a 500 gr rn. why use a light bullet for sub sonic the heaver bullet gives better ballistics down range.

Mr. Squirrel is chewing his nut and pondering on that one. I'd go all .310 round ball and a primer.. well, maybe a pinch. lol

 

[FA9]

According to the NOAA, Speed of sound in FPS
is dependent on the density of the air...
is dependent on the temperature of the air.
99f = 1158.39
95f = 1154.23
90f = 1149.02
85f = 1143.78
80f = 1138.52
75f = 1133.23
70f = 1127.92
65f = 1122.58
60f = 1117.22
55f = 1111.83
50f = 1106.42
45f = 1100.98
40f = 1095.51
35f = 1090.02
30f = 1084.49

No matter how careful you are with someone else's recipe,
You have no way to prove your results unless...You use a chronograph.

I own a Chrony F Chronograph, purchased in 1988, and a CED-M2 purchased this year.
I would not work-up a load without them.

With subsonic ammo you work in reverse. Start high, and work your way down.

 

[rick benjamin]

• How much risk will I be taking if I work up my own loads? For example, if I took a subsonic recipe with a lighter bullet and substituted a heavier bullet.

How much risk? It depends.
Substituting ingredients, how would you know the outcome?
Folks don't have any problem shooting factory ammo in a firearm. They trust it.
Someone had an M1A last Monday evening at DRRC Dynamics Range.
Wednesday morning I was policing the range and found pieces.

We RSOs discussed how new it looked, couldn't find any more pieces.
We see a lot more kabooms in the past couple years. This fall we may ban reloads at hunter site in.

 

[ConcreteJungle]

How much risk? It depends.
Substituting ingredients, how would you know the outcome?
Folks don't have any problem shooting factory ammo in a firearm. They trust it.
Someone had an M1A last Monday evening at DRRC Dynamics Range.
Wednesday morning I was policing the range and found pieces.
View attachment 247179 View attachment 247180
We RSOs discussed how new it looked, couldn't find any more pieces.
We see a lot more kabooms in the past couple years. This fall we may ban reloads at hunter site in.

Did that happen with a factory load? Or reloads he was experimenting with?

 

[rick benjamin]

Not known. No accident report was submitted.
We know it was a new M1A (.308), shrapnel in the mag box. No blood evident.
I worry about reloaders that are not safe, and folks who use their product.
Changing powders, changing bullets. Reloading for their friends, not testing.
Not chronographing.

 

[ConcreteJungle]

Not known. No accident report was submitted.
We know it was a new M1A (.308), shrapnel in the mag box. No blood evident.
I worry about reloaders that are not safe, and folks who use their product.
Changing powders, changing bullets. Reloading for their friends, not testing.
Not chronographing.

Glad you didn't see an blood, that's a good sign i guess.

 

[rick benjamin]

This is how I would work this load.
Consult "Sierra Bullets Reloading Manual"
Suggested primer Remington 9 1/2 per Sierra book
Caliber 308, 200 grain Sierra Matchking Hollow Point
200gr is the heaviest recommended by Sierra book for a 308.
Powder IMR-4064 36 grains registered 2200 feet per second, per Sierra book.
Desired velocity at 70 degrees Fahrenheit less than 1127.92 feet per second
Load 3 rounds at 36 grains, shoot over a chronograph to confirm velocity.
If velocity confirmed reduce to 35.5 grains and shoot. Record velocities
Continue to reduce load by .5 grains till recorded velocity nears 1127 fps
Reduce loads by .1 grains till you attain 1100 fps.
Good luck

 

[rick benjamin]

Glad you didn't see an blood, that's a good sign i guess.

How much risk will I be taking if I work up my own loads?

If you Kaboom a Springfield Standard M1A $1500, A supermatch M1A runs $3500
If shooting from a bench on sandbags or a rest with body parts behind the trigger,
Maybe no injuries.
If triggering with right hand and anchoring the forend with left hand,
Serious injury to left bicep, elbow, forarm, wrist, hand.
Wood splinters to the head, upper torso.
If the receiver-bolt rupture, they may come back into the face.
Rare, as military guns tend to hold together.
What might it look like?
google "gun kaboom injuries" to see blood guts and feathers

 

[Liberty97045]

How much risk? It depends.
This fall we may ban reloads at hunter site in.

Please don't

 

[Liberty97045]

So I loaded up some this weekend and they are AWESOME!!!

I used 10 grains of Trail Boss with a CCI Magnum Primer and a 168 grain HPBT

Min 1003 fps
Max 1031 fps
BP 30.1
Temp 71F

I was shooting a Savage 10FCP-SR with a 24" barrel. Without the can it was slightly less noisy than a 22LR from a rifle. WITH the can, freakishly quiet.

 

[Certaindeaf]

This fall we may ban reloads at hunter site in.

It's sight.. not site. good luck with that anyway

 

[rick benjamin]

There were several kabooms last September.
Fortunately, no one was hurt.

I saw a separate thread from Liberty97045, has his own chronograph.