Sub-sonic 308 load - help

TRGOD36

TRGOD36

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I'm working on a sub-sonic load to use in my Norc M14 (.308) and I need some more info. I've check some pass postings but still have a couple of questions.
The load so far.
Using 180 grain Lead RN FP bullets, large rifle primer and Winchester brass for all loads.
Started at 12 grains of Trail boss powder and worked down to 11gr, 10gr and finished at 9gr. It still allot louder than I want but I'm wondering how much lighter I can safely go.
Is anyone loading less than 9grs in 308?
Is there a better combination for this.

I don't anticipate using this load for any shots beyond 25yrds

And yes I'm new to reloading.
Thanks
 
That could very well still be super sonic. I don't suppose you have a Chrony?

I have made sub sonic for suppressed rifles and used 2400. I was loading 200 gr jacketed bullets.

I suggest you keep reducing the charges, but put a little wad of pillow stuffing on top of each powder charge. I stuff a wad in with a pencil.
 
Ganderite said:
That could very well still be super sonic. I don't suppose you have a Chrony?

I have made sub sonic for suppressed rifles and used 2400. I was loading 200 gr jacketed bullets.

I suggest you keep reducing the charges, but put a little wad of pillow stuffing on top of each powder charge. I stuff a wad in with a pencil.
Click to expand...

No Chrony.

Will the pillow stuffing get into the gas system?
 
Hmmmm. Don't know. It is a synthetic. I load for a supressed bolt rifle and have never seen any sign of the wadding when cleaning.

I understand what you are trying to do. I just checked my log book to see what I have tried. All testing was with 2400. There is no reason why a pistol powder would not work. I see by my notes that with and without wads gave the same results. Skip the wadding.

You have to reduce the powder charge to slow the bullet, but still need a good pressure peak to burn the powder reliably (for accuracy). Here are some things you can do:

-Go to a heavier round nose lead bullet. A 200 might be best.

-Seat the bullet long so it engages the rifling. This will boost peak pressures.

-Try a fatter bullet. I have tried .312 bullets intended for my 303.


Turn off the gas system. Turn the slot head screw a quarter turn on the side of the gas block. Low pressure loads are dirty.

I recall making ammo like what you want. We were shooting it in the back yard and it sounded much like a 22. Not bad for a 308.

But be careful. You are still developing more power than a 357 magnum.
 
Not sure about that weight in a lead bullet. I shoot 180 Hornady RN bullets in my 308. The trick with the jacketed bullets it to first run an oil patch down the barrel and then apply a bit of oil to each bullet with your fingers. Otherwise, velocities will be all over. 10.1 gr. Trailboss or 8.0 gr. Titegroup both give around 1020-1040 fps. It still sounds like a supersonic .22 LR. It won't be suppressor quiet.

Without a chrono, you're running completely blind. At least lead bullets are pretty easy to pound out of the barrel...
 
I load 7.0 gr of Trailboss in my .308 lever action using 150 gr L-FN bullets & Win. L.R. primers. Velocity is 1061 fps. Accuracy is good and very little noise with no recoil. However, 9.0 gr is more accurate, at least for me. Velocity on this load is 1225 fps.
 
TRail Boss can be ran pretty low and still ignite...I have not found it to be a real dirty powder.. certainly better than Unique...

I've ran it down to about 800 fps, in a 260 w/140 grain Bullets... I thnk the charge was about 6 grains of Trail Boss...pistol primers...
 
Why not? I use them with a friend's suppressor. There are still plenty of uses if can't have suppressors where you live. You can carry a few with you when hunting big game for if you want to shoot something small without obliterating it. You can shoot it at any steel target or backstop thats only rated for pistol. Kids and the wife can shoot the "big gun" without the blast or recoil... There are many reasons.
 
Some on here have been referring to the speed of sound as being about 1100 feet per second. Actually, speed of sound is about 1100 miles per hour, which is about 1633 feet per second.
I don't think speed of sound, or sub sonic, has anything to do with how much noise your firearm makes. Load the 308, or any other rifle low enough and it will sound like a 22. And no, you can't load pistol powder too light in a rifle, just make sure the bullet gets out the barrel.
If sub sonic was quiet, then why aren't pistols quiet when they go off? Virtually all pistols are sub sonic, and we know a bullet travelling 1000 feet per second in a pistol makes much more noise than the same weight bullet travelling at the same speed, from being loaded down in a rifle.
The short barrel of the pistol is what makes it so loud, whereas a long barrelled rifle using pistol powder has the powder all burned before the bullet gets out the barrel, thus is quite quiet.
Sorry to rain on your picnic, with all the fun you guys are having, but lets talk about facts.
 
As I understand it, the speed of sound is approx 340m/s @ 20deg C at sea level in dry "air". Temperature, humidity, "air" composition all have an effect. This translates to roughly 1,125 ft/s. The "crack" from the bullet breaking the sound barrier can be eliminated by preventing the bullet from reaching these speeds. This doesn't mean that the shot will be completely quiet; there is, after all, still a small "explosion" happening. The shorter the barrel and the bigger the bore the louder it will be. Thats my understanding on the subject, but its been awhile since high school physics.
 
diemaco said:
As I understand it, the speed of sound is approx 340m/s @ 20deg C at sea level in dry "air". Temperature, humidity, "air" composition all have an effect. This translates to roughly 1,125 ft/s. The "crack" from the bullet breaking the sound barrier can be eliminated by preventing the bullet from reaching these speeds. This doesn't mean that the shot will be completely quiet; there is, after all, still a small "explosion" happening. The shorter the barrel and the bigger the bore the louder it will be. Thats my understanding on the subject, but its been awhile since high school physics.
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Explain what you mean by the crack of the bullet breaking the sound barrier. It sounds like you mean the bullet leaves the barrel, then breaks the sound barrier as it picks up speed. Maybe you should look up those physics!
Some where down range when it slows to below about 1600 feet a second and breaks the barrier, you may hear something, if you were there.
I will stick to what I said, speed of sound, or breaking the barrier, hasn't anything to do with the noise from our guns.
As a point of interest, with a bottle neck rifle case at normal power, the bullet reaches the speed of sound by the time it has travelled about 1½ inches down the barrel!
Juster, you said this:---No it isn't.
Please explain what is not right, or what you mean.
 
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Being subsonic is only of interest if you have a silencer/supressor, no supersonic "crack." Just being slow in general I understand however.
 
rommelrommel said:
Being subsonic is only of interest if you have a silencer/supressor, no supersonic "crack." Just being slow in general I understand however.
Click to expand...

There are many reasons something may be of interest. Loading to trans-sonic/subsonic velocities is just another subject for the student of small arms, as is the study of long range shooting, or the terminal effects of bullets. At some point in the uninterrupted flight of a supersonic bullet it will become subsonic. Determining how subsonic velocity might impact on the stability, accuracy, or terminal effect of a given bullet is easier to document at close range than it is at a half mile thus you load to trans-sonic or subsonic velocities.
 
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