I have been researching a few good loads for my .308, I have a suppressor and I wanted a nice mouse fart load! I started at 11.0 Grains of Trail Boss and worked my way DOWN to 9.0 grains. The 9.0 Grain was not accurate and didn't stabilize the bullets even at 50 yards.

Here is what I came up with:

Lapua Virgin brass
BR-2 Primer
10.0 Grain of Trail Boss
170 Grain Round point 30-30 bullet .308 diameter
2.685 OAL


Very Very Very quiet and accurate out to 100, easily shot sub MOA at 50 yards and about MOA give or take at 100 yards.


Oh ..here is a video comparison. The first round is a full house Southwest Ammo 155 grain palma load that is 2900FPS @ the muzzle! Scootin! The second shot is a mouse fart sub sonic.


Rifle Specs:

M40A3 Clone
Schnieder 1-11 twist bbl Cut @ 23.5 threaded 5/8x24
Mcmillan A4 stock, with adj cheek piece sniper fill
Rem 700 action trued
Rem factory trigger (non ex mark) tuned to 2.5lb
Badger M5 bottom metal

http://www.youtube.com/watch?v=OtaP6AdDA80

You need a chrono! What rifle are you shooting from... barrel length, twist, etc? I have been playing around with a suppressed .300 Whisper T/C Encore for a year and a half, and the subsonic game is addictive. I have killed a pile of deer with various 220-240 gr bullets, and have completely switched to 220 gr Outlaw bullets for hunting due to the complete failure of standard bullets to expand.

Paul from Outlaw State Bullets recommended the following Subsonic .308 Win load to me:

225 gr Outlaw bullet
12.0 gr IMR 4759
Federal 215M primer
Barrel length needs to be 20" or less, 1/10" or faster twist

*I have not loaded any of these yet, but will report back when I do

I am putting a 300 blackout upper together right now and will order my can once Immortal is back from vacation. I can't wait.

What suppressor are you using?

Shark Suppressor. Very small company based out of Texas.

I run a YHM Phantom on my 300 Whisper

just walked in the door

So do you know the velocity of your sub round. I take it the heavier the bullet the more energy with less velocity. Good to hear your dropping deer with a subsonic load. That's my goal!

My 220 gr loads average 1020 FPS through my CED Pro Digi chrono. I dont like to push them too close to the sound barrier, wouldnt want to "accidentally" have one go sonic in some of my suburban hunting spots.

Downrange energy is mass times velocity. Subsonic ammo takes the velocity variable out of the equation by limiting it. So the only way to hit something harder is with a heavier bullet. The only problem is stabilizing them... most factory 308's wont stabilize a 220-240 gr bullet.

^ this sounds like fun!

Loading your own and hunting with subs is a lot of fun... it's downright addictive. And with .300 Whisper, .300-221, and now 300BLK components readily available for assembly in standard AR-15 uppers, you can get into it pretty cheap. Of course, you can always go bolt-action or single shot (Match Grade Machine makes excellent custom barrels for TC Encores) if you really want to get quiet!

I've been looking at the 300blk for a build for next years hunting season. Seems like it was designed for subsonic loads.

Great information, I have an SSK 300 Whisper on the AR platform suppressed and am really enjoying working up loads for this as well. Haven't had the opportunity for deer hunting with it yet, but I'm intrigued, I'll have to check out the Outlaw State Bullet site you recommend.

I'm in the process of having a SOCOM 16 set up with a suppressor as well and I've been advised to be careful in the .308 with sub-sonic loads for the 200 gr and heavier bullets as they can get lodged in the barrels with 1-12 twist rifling.

Chrono is a must have, you may want to check out the Ballistic Explorer computer program from Oehler research as well, it's a valuable asset to reloading!!

Would you mind sharing the "deer hunting" load information for the 300 Whisper?

Good Shooting,
Semper Fi

I am in no way affiliated or sponsored by them, but I really cannot recommend Outlaw bullets enough if you are hunting with subsonics. This heart was removed from a doe, shot at 20 yards with a 220 gr Outlaw Lead Tip Spitzer at 990 FPS. Bullet fragmented perfectly and completely destoyed the vitals, leaving a 1" exit hole out the far side. Every shot I've taken at deer with them has had similar devastating effects.

My hunting load (at own risk):

.300 Whisper T/C Encore, 16" 1-8 twist, YHM Phantom suppressor

220 grain Outlaw State Bullets lead tip spitzer

3x fired Remington 221 Fireball brass formed and trimmed to 1.350"

8.70 grains of Accurate #9

CCI small rifle primer

O.A.L. of 1.668" as measured off the ogive with Hornady .30 Bullet Comparator

Total C.O.A.L. of 2.140" (average - lead noses are notoriously imperfect)

Sub-MOA accuracy out to 100 yards. Seating depth seems to really be the key for this. Took me a lot of testing to find the "sweet spot".

Averages for 5-shot groups have been 1006, 1009, and 990 FPS at 70-75 degrees.

I use virtually the same load with a 220 SMK for plinking - same POI and bullet drop out to 100 yards, but much cheaper.

This sounds like a lot of fun!

One of my ammo suppliers has a factory sub .308, 175gr 1060 fps. They just notified me that they are doing a production run so I will be ordering some to test out.

Many thanks, I'll be looking into the Outlaw bullets and I'll let you know if I can work up a decent load!
thanks again,
K

The sub .308 load that I shoot is:

10.8 gr. Trailboss
CCI LR primer
Fed. GMM case
Hornady 180 gn. RN

This load does 1040-1050 fps. out of a 20" Rem. LTR.with a 1/12 twist barrel. Can't do 220s as its not fast enough to stabilize. I have not tried it out of my GAP Rock as I am sure it would break the sound barrier because of the longer barrel. It shoots MOA at 100 yds.

Anyone shooting Trailboss powder in .308 Win subs noticed their velocity drops significantly with each consecutive shot in a group? As an example: 1st shot- 998, 2nd- 956, 3rd- 931, 4th- 908...

I'm loading 10.7 grains Trailboss under a 180 gr. Speer flat-base sptizer, shooting out of a Rem 700 SPS Tactical 20" (1/10 twist) through a YHM Phantom. First round of every group is right on the money (1006, 998, 996...) but each round after drops 20-40 FPS. Wait 20 or 30 minutes and the velocity goes back to my "target" number. I repeated this phenomenon over two days with several different loads. Is Trailboss THAT temp sensitive??? I have read one other loader having this problem, but there must be others.

I too shoot subsonic 308 rounds. I use trailboss in both of the rifles I shoot. I dont typically shoot subs out of my GAP10 as it doesnt cycle the bolt (Need a 300) but that load is 10.5 Trailboss with cci200 primer in whatever case I have and 180 Hornady RN bullets. This rifle is 18.5" with 11.25 Twist.

In my remington 700 26" 1:12 I run 9.6 Trailboss with CCI 200 Primers in whatever case and the same hornady 180 RN.

I run a surefire can on both. Both provide 1050 FPS and can easily and repeatable make hits on 12X12 steel out to 300Yards.

JR, I have not experienced those types of swings in velocity. I would speed it up about 30-50FPS and see what happens.

my current load is

a Speer 2053 which is a soft point 180gr. 11 grains of Trail Boss in a Hornady Case with a Federal LR Primer.

The OAL is 2.81 and i opened up the flash holes to 9/64" to help burn all the powder.

I do not have a chrono (i know i need one lol), so i don't know the velocity exactly, but they are definitely subsonic. I can keep the group at about an inch at 100yds. To compare, my standard load with a 178gr Amax can shoot just under 1/4" at 100yds.

The rifle is a Rem 700 varmint so unfortunately has the slower 1:12 twist so 180gr is about as much as it can do it seems.