.308 win subsonic loads


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farmerboy78
August 26, 2012, 11:37 PM
hey guys, i will receive my new savage 10 pc .308 soon and i am wondering about some subsonic loads. will be using 168 gr federal match gold for supersonic.

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greyling22
August 27, 2012, 01:55 AM
do standard 308 barrels have twists that stabilize subs?

ATCDoktor
August 27, 2012, 10:55 PM
Loading subsonics is a little different than loading standard rounds. You want to start "High" and work down till you get to 1000 FPS.

If you start out low and work up, you may stick bullets in your barrel.

It has been my experience (with regards to 308 subsonic loads) that boat tailed bullets (of any weight) turn and fly base forwards out of barrels with twists of 1 turn in 10" when fired at subsonic speeds (they usually make the "turn" inside 50 yards).

Flat based bullets fly true at subsonic speeds (in my barrels rifled 1:10) and group well out to 100 yards.

My standard load for subsonics in my Remington model 700 SPS with 1:10 twist (20 inch barrel) is 8.8 grains of Trail Boss in Lake City brass with a 150 grain Sierra Flat nosed 30-30 bullet (Wolf Large Rifle Primer).

Velocity is right at 1000 FPS and the bullets are subsonic at 80 degrees F and at an Altitude of 200' asl.

Keep in mind that as the temperature gets closer to freezing the easier it is to break the speed of sound (this goes for altitude as well, the higher the altitude the thinner the air the easier it is to get your rounds to "Crack").

So, your "summertime" subsonics may break the speed of sound in the wintertime and your near sea level rounds may "Crack" at your cabin/shooting spot in the mountains.

Hodgdon lists the starting load with Trail Boss as 10.0 grains using a 150 grain bullet.

Start there and work down slowly and you shouldn't have any problems.

Strongbad
August 27, 2012, 10:56 PM
Some do. The factory ammo that I've seen that was made subsonic for suppressed guns was loaded with big heavy RN bullets.

I think your best bet is going to be with Trail Boss. Check out the Hodgdon page. They have instructions on how to load Trail Boss in a rifle case. It should allow you to get down in the subsonic range. Are you shooting a suppressed rifle, or is this just for fun? I say this, because subsonic or not, without a suppressor, it's still going to be loud. :)

Swampman
August 28, 2012, 03:04 AM
If you really want to work up good, accurate and safe subsonic loads, my suggestion would be to start with round nose, flat base, cast lead bullets. At subsonic speeds, cast bullets usual disadvantages compared to jacketed bullets vanish and their good qualities really shine. You're also much less likely to stick one in your bore and if you do, they're much easier to remove.
If you make sure that all traces of copper fouling are removed before you start shooting cast and then lube your bullets well, leading is a non issue at subsonic speeds.
I seem to get better accuracy and consistency with gas checked bullets than I do with plain based, but that may have more to do with my casting abilities than any inherent superiority of the gas checked bullets.
I agree that Trail Boss is a good powder to start out with due to the fact that it's fairly safe as long as you don't compress it. However I've pretty much moved on to other powders that are both cheaper to use, and in my experience, more accurate with subs.

Here are some links to a couple of websites that were very helpful to me when I started loading subsonics.

http://members.shaw.ca/cronhelm/DevelopSubsonic.html

http://guns.connect.fi/gow/arcane1.html

Good Luck and Stay Safe,
Swampman

kingmt
August 30, 2012, 04:10 PM
In 30-06 I had my best results with 147gn fmj turned around backwards.

tango2echo
August 31, 2012, 11:49 PM
I have been using the MBC Whitetail #1 165gr RNFP with around 11.5-12.0gr of Trailboss. From a 22" BBL I get about 1100fps. I started at 14.0gr and worked down. Around 10.0gr they stick in the bore.

Very quite. The crosshairs never leave the target under recoil. 1.25" groups @ 100 and about 2.5"-3.0" @ 200. It is about a foot low @ 150y, and right at three feet at 200y. It is pretty fun head shooting bunnies at 200y with it. If you miss they usually don't even run off. :what:

T2E

farmerboy78
September 4, 2012, 08:32 PM
Well I have an update on some loads. I tried loading some 220 grain SMK backwards like a lot of people say to do and none of them would stabilize from a 1-10" twist. But they will forward like normal...

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