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Posted: 9/4/2010 7:16:54 PM EDT
Took my SAS .30 cal can out today for the first time. It's a blast to shoot! Normal loads are nekkid ear safe for me and the subsonics are flat amazing! I had a question about the subsonic loads, thought. I loaded up some150gr PSP and 180gr RNSP bullets of 9.0 and 10.0gr of Trail Boss, respectively. Heeding teh warnigns I"d read, I fired a few rounds, without the can, at about ten feet and 25 yards. All holes looked good; perfectly round. When I moved to a hundred yards with the can on it, the 150's were hitting sideways on paper. I had one 150 go supersonic, so they must be right on the edge for the temp/elevation/etc. All of the 180's stayed subsonic and shot into about 2" groups at 100 yards. Rifle is a FNH PBR with a 1:12" barrel on it. I"m happy with the 180's for subsonic loads, just curious why the light weight bullets didn't stabilize when the heavier ones did. This seems backwards to me.

Thanks for any insight.
Link Posted: 9/4/2010 8:10:18 PM EDT
For my subs i use soft point round nose 180gr. They're basically just old hunting bullets I got from a neighbor. My Savage is 1:10" twist, and it stabilizes everything I've tried so far, both sub and super. I have found that the heavier bullets (i.e. 180gr) are easier to launch subsonic and reliably stay subsonic, so that's what I stuck with.

To be honest, shooting subs was fun for a little while as kind of a novelty since I could do it at home and not wake the baby... But I kind of haven't done much at all with them for a few months now. It is fun to take a few to the range and watch the jaws drop...


cheers, Benji
Link Posted: 9/4/2010 8:30:58 PM EDT
I would guess that your keyhole is due to the fringe speeds your are getting..

If you back off some and ensure they are staying subsonic you will likely not see that.

or if you keep them supersonic you should not see it..
Link Posted: 9/4/2010 10:33:21 PM EDT
I use 180gr factory EBR Thumper. Got scared reading about SEE with handloads.
Link Posted: 9/5/2010 3:09:53 AM EDT
Originally Posted By themcfarland:
I would guess that your keyhole is due to the fringe speeds your are getting..

If you back off some and ensure they are staying subsonic you will likely not see that.

or if you keep them supersonic you should not see it..


I never thought of that. I know that .22 target ammo is usually subsonic as funky things happen when bullets cross the sound barrier. I guess I"ll cut the charge down some and try another batch. I'll take the chrono with me next time. This time was more of a fun outing!
Thanks for the input.
Link Posted: 9/5/2010 7:27:28 AM EDT
Remember that temperature and humidity affect the "speed" of sound. So what goes super in the morning may be subsonic in the afternoon... I've been surprised a few times shooting off my back porch when a load that had always been subsonic went super because of the weather... I haven't had that issue ever with .308 but loading subsonic .223 has been quite a bit more tricky.
Link Posted: 9/5/2010 6:45:06 PM EDT
Remember, also, sub-sonic flight is more stable with a rounded nose or weight forward (yes, as in load the bullets backwards). This can help when you twist/weight/speed are borderline.

One of my favorites to shoot is my SAS can on a 7.62x39 rifle with subs. Sunsonic and still cycles with no modifications......

Dan
Link Posted: 9/6/2010 9:26:29 AM EDT
I tried some a couple of times, I used a 168gr SMK and 8.1 grs of Tightgroup. If the sun angle was just right you could see the copper bullet flying through the air, looked like I shot it with a sling shot.

My groups at 100 yards were a little over an inch. I haven't played around with them in a while though. I got the load data right from Hodgdon, only their load data called for a 168gr. A-Max.

Very quiet, the loudest part was the bullets hitting the target.
Link Posted: 9/6/2010 11:33:09 AM EDT
Yah, the sound of the bullet hitting the target is fun... I load up those round nose 180's partially because that's what I had lying around, but I read (like was stated above) that a big 'ol round nose stabilizes easier/better at subsonic velocities.

I have yet to load any backwards... I have wanted to try it, but since my groups with the 180's have easily been minute of coyote vitals @ 100 yds I just stuck with that.
Link Posted: 9/6/2010 12:27:09 PM EDT
Originally Posted By benjio:
Yah, the sound of the bullet hitting the target is fun... I load up those round nose 180's partially because that's what I had lying around, but I read (like was stated above) that a big 'ol round nose stabilizes easier/better at subsonic velocities.

I have yet to load any backwards... I have wanted to try it, but since my groups with the 180's have easily been minute of coyote vitals @ 100 yds I just stuck with that.


You use trailboss for your powder right? I have read its better for subs, because you get better case fill. Useing tightgroup, you get less than half the case full which makes me wonder sometimes if I am going to get a bullet stuck in the barrel.

For my .223 ar I use 3.1 grs of tightgroup with 55gr FMJBT, these are stupid quiet. It sucks that subs don't cycle though. I think a .300 whisper upper would be sweet.
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