View Full Version : Subsonic 308 - Post Experiment Report

April 12, 2007, 07:50
My goal:
To create a subsonic .308 load with enough down range power to make it worth the effort of loading.

-Mag. rifle primer
-6.0gr Unique
-147gr M80 (loaded UPSIDE DOWN!!!! )
-Brass doesn't make any noticeable difference
-Seat the bullet to the canalure
-Lee factory crimp

≈925 fps @ 5 yards from the muzzle (279 ft/lbs of energy)

Slightly louder then a 22LR, but MUCH quieter than a full power load. I'm sure that staying subsonic makes a big difference on the volume level. My rifle is dead on at 100 yards, and a hair low at 25 yards. At 25 yards, the subsonic loads are about 2" or so low. Not great for anything but close shots, but you never know when they will come in handy.

Loading the bullet right side up (point out) lowered the velocity by about 15 fps, but didn't hold a group quite as well. Loading upside down puts the weight balance toward the front, keeping the bullet more stable in flight.

I wouldn't run this load with anything but a boat tail bullet. I don't know how a flat nose would grab the lands.

As for other weights, I tried 110gr M1 carbine, and a 125gr Speer "TNT" (loaded right side up) with the same powder charge. Both stayed subsonic, but as you can imagine, lower bullet weight = higher velocity. The groups are not as low as the 147gr, but they are still low compared to a standard loading.

All rounds tested cleared the muzzle - my chronograph told me so.

For an afternoon at the range, load a 110gr bullet right side up with 10gr of Unique and plink away. Expect velocities around 1400 fps. Low recoil, and you get 700 rounds from 1 lb. of powder.

Load 1 or 2 boxes of subsonic rounds and put them on the shelf for that rainy day we all hope never comes.

April 12, 2007, 12:10
You need to load a heaver bullet. I have some Speer 190 IBTHPs.

Loading the bullet backwards is just screwing your ballistics.

Just my opinion.

April 12, 2007, 14:50
I wonder how a heavy round nose bullet would perform?

April 12, 2007, 15:25
If you really want to create havoc at your next steel plate competition, load the bullet upside down with the regular charge. I can guarantee you there will be some nice holes punched right through the steel.:uhoh: It will shoot through a train track, I used to do that with my SADF R1 (and I used my own piece, not the South African Railway's).

For some quiet 223 loads, try 13 grains of Blue Dot with a 50 grain hp bullet. It will not be subsonic, in fact it will go about 2500 feet/sec, but will be a lot quieter than a full power load.

April 12, 2007, 16:37
I've got a partial box of carbine bullets. I think I'll try it and shoot them out of my Israeli K-98.

April 20, 2007, 08:50
I've got a partial box of carbine bullets. I think I'll try it and shoot them out of my Israeli K-98.

the most accurate handload i ever did was with 110g carbine bullets in my two-groove 03-A3. sub-moa.
Dave Dude

April 20, 2007, 09:10
I have played around with light powder charges and bullets loaded both ways for years. I could not tell much differance on how the bullet was loaded. The only bullet I now load backwards is a .357 HBWC in a 38. I have went to copper plated cast or gas checked cast over a 11 or 12 grains of 2400 in a 30-06. Same bullet in a 30-30 over a small charge of Red Dot also works well. I realy like a 60 grain cast bullet over Red Dot in a .223. The load is quiter that a 22LR. I have killed a lot of small game with that load. If I can ever talk my sister in law to giving the rifle back I will kill more with the load.

April 20, 2007, 23:50
Originally posted by Azrial
You need to load a heaver bullet. I have some Speer 190 IBTHPs.

Loading the bullet backwards is just screwing your ballistics.

Just my opinion.

When you have marginal rotational stability the pointy end wants to swap with the heavy end (rock in a sock aerodynamics) - same thing as falling water droplets better stabilty. A heavy short bullet like a 170grn fp 30-30 bullet might be a better choice. hmmm - but cost factors into that as pulled 147's are pretty cheap to plink with.

April 22, 2007, 23:39
yeah, i can tell you about real quiet loads.

wax bullets over a primer only in 38 spec will go through your wife's new towels when fired in a basement range.

1. deprime and resize fired cases
2. reprime
3. melt craft wax in a cookie sheet and allow to harden in 1/2" thickness
4. push open end of cases into 1/2" wax after it hardens in the pan
5. hang paper targets in the basement
6. hang wife's new towels up as a backstop so you can re-use the wax
7. shoot several groups before noticing the towels are now full of holes
8. tell your wife those new towels were attacked by moths in the basement

April 23, 2007, 00:13
Can we presume that all of the quiet loads will not function a FAL?

Shooter, A hunk of scrap carpet works very well.

April 23, 2007, 11:44
j.a.s, would that be reason #357, out of 1001, that you're lookin' at China Dolls fer a new wife?