It's been done, but now it's my turn

[308sako]

To play with sub sonic reloads in the 5.56/.223 Remington.

http://www.snipercompany.com/forum/gallery/image.php?album_id=4&image_id=2212&view=no_count

Shown is the 70 grain Speer softpoint and a loaded cartridge at 2.245" COL, also shown is a 69 Sierra MatchKing and loaded cartridge for comparative purposes.

Using the Hodgdon data as provided here: http://data.hodgdon.com/main_menu.asp

Proved to be a failure as their suggested load of 4.0 grains of IMR TrailBoss powder remained supersonic. 55 FMJ (Hornady) 1140 ft/sec in my 18" Rock Creek barrel and 1166 ft/secs in my 11.5" Bravo Company. Additionally, the shot to shot variation was considerable, so my hope is using a heavier bullet will even things out.

Yes I know that you can get a .22LR to be very quiet, but I have no desire to lead plate my AAC. Besides this is for giggles and the experience of getting rid of old accumulated components: Speer 70 grain softpoints in this case.

I will not be able to shoot these until next week, but the charges chosen are 4.2, 4.4, 4.6 & 4.8 grains of TrailBoss.

Anyone care to guess which will be the quiet one?

Now with video link: http://s181.photobucket.com/user/308sako/media/SubSonics_zps266bc281.mp4.html

Listen for the 100 yard steel plate impact. Hollywierd quiet....

[308sako]

5.6 grains of TrailBoss with 70 grain Speer SP, 18" melonited Rock Creek 1 in 8 twist 5R rifled barrel, velocity 989 ft/secs SD 12.

Same exact load in the 11.5" BCM 1 in 7 twist CL LW button tube; Velocity 1062 SD 10.

Tried 5.5 grains with CCI small pistol magnum primers and got the most consistant ignition... Velocity 1049 SD 8 in the 11.5 BCM tube.

"That's All Folks"

[SeriousStudent]

Thank you for this data. I've been very interesting in developing a similar load. I appreciate you posting your research.

[Tzed250]

I believe they also list a subsonic load using Titegroup.

[308sako]

video link in OP