Suppressors .308 Subsonic load testing (1080P video)

[Conqueror]

Just some preliminary .308 subsonic load testing I filmed at the range a couple days ago.

http://www.youtube.com/watch?v=8PdowWhqYn4

The 170gr FP bullets are seated long to kiss the rifling and don't feed well from the magazine at that length due to the massive tip, so I edited out the single-loading of each round through the ejection port. Once I have a set load, I'll start loading them deeper to feed better, as they seemed pretty jump-tolerant in my previous non-suppressed experimentation.

Ultimately I'll probably switch to something in the 190gr class but the local supply had these for cheap and I figured it was a good starting point. The 1:11 Sako twist should even be good into the 200gr region, as the Miller number is pretty high for 180gr RN at 1050fps. I have another batch loaded starting at 9.5gr that I'll be testing tomorrow.

 

[stefan73]

Re: .308 Subsonic load testing (1080P video)

Email or PM Short-Buss/Dustremover. He has a video of us playing around with various sub and super sonic loads on the Thunderbeast. I think my best load was 9.5 grns of TB with 190grn SMK out of my Sako TRG-22 with a 20" barrel, you can here the click of the firing pin over the sound of the round firing which is dwarfed by the ring of steel at 100yards.

Everything sub/below the 190grn projos that had available seemed to demonstrate some slight yawing/tumbling/lack of stabalization. I didn't try anything heavier.

 

[Fred_C_Dobbs]

Re: .308 Subsonic load testing (1080P video)

Conqueror, are you sure those are subsonic? The only thing I shoot subsonic and suppressed is a rimfire but I definitely can hear the difference when I'm shooting subsonics because I can't hear any echo.

I hear echo in your videos.

 

[stefan73]

Re: .308 Subsonic load testing (1080P video)

Funny that I had the crack at about 9.8-10grns of Tb when I was working the loads. Used LC brass and FED primers.

 

[springer01]

Re: .308 Subsonic load testing (1080P video)

Why did you continue to shoot after you got supersonic? Seems like you went backwards to me, I started at 10.0 when I got to 10.2 I was supersonic and that was enough testing for me. Pulled my others and loaded them down to 10.0. Just curious.

And Fred yeah you can clearly tell the first few shots are subsonic vs the later shots. Listed for the crack...

 

[eight]

Re: .308 Subsonic load testing (1080P video)

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: springer01</div><div class="ubbcode-body">Why did you continue to shoot after you got supersonic? Seems like you went backwards to me, I started at 10.0 when I got to 10.2 I was supersonic and that was enough testing for me. Pulled my others and loaded them down to 10.0. Just curious.

And Fred yeah you can clearly tell the first few shots are subsonic vs the later shots. Listed for the crack... </div></div>

Agreed. Not sure why you kept shooting if the goal was to find the limit. I kept waiting for you to go back to what was subsonic. Either way, you know what works now, which was the point.

 

[Conqueror]

Re: .308 Subsonic load testing (1080P video)

I kept shooting because that's what I had loaded up, I wasn't loading these at the range, and in my mind it wasn't worth the $2 in savings to disassemble like 10 cartridges. Shooting them was still fun despite the crack. There's a good graph in one of Al Paulson's books of bullet flight noise vs velocity, and it does increase linearly even in the subsonic region. So if quiet is the only goal, you'd be better off with even less powder, like 8gr or something. But I'd rather it be a touch louder and still pack some punch if I choose to hunt with them. I will likely settle on whatever load is just under the transonic threshold (around 10gr, it seems).

 

[Conqueror]

Re: .308 Subsonic load testing (1080P video)

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Stefan73</div><div class="ubbcode-body">Everything sub/below the 190grn projos that had available seemed to demonstrate some slight yawing/tumbling/lack of stabalization. I didn't try anything heavier. </div></div>
That doesn't make much sense. For a given twist, lighter should be more stable. The 168gr SMK is shorter than the 190gr. You got good stability with the 190 SMKs? I was thinking of trying them but I would guess that a 190 flat point would have better terminal performance than an SMK at 1000fps...

 

[stefan73]

Re: .308 Subsonic load testing (1080P video)

The 190 SMK worked great for me. I would test it first since every rifle is different.

 

[Short-bus]

Re: .308 Subsonic load testing (1080P video)

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The 175's worked fine Stefan, but I distinctly remember seeing oval's in the paper from the 168's. They didn't fare so well.

 

[springer01]

Re: .308 Subsonic load testing (1080P video)

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Conqueror</div><div class="ubbcode-body">I kept shooting because that's what I had loaded up, I wasn't loading these at the range, and in my mind it wasn't worth the $2 in savings to disassemble like 10 cartridges. Shooting them was still fun despite the crack. There's a good graph in one of Al Paulson's books of bullet flight noise vs velocity, and it does increase linearly even in the subsonic region. So if quiet is the only goal, you'd be better off with even less powder, like 8gr or something. But I'd rather it be a touch louder and still pack some punch if I choose to hunt with them. I will likely settle on whatever load is just under the transonic threshold (around 10gr, it seems). </div></div>

I follow you! I used a chrono too so I knew exactly where I was at. 10gr TB and 178 AMAX did the trick for me!

 

[stefan73]

Re: .308 Subsonic load testing (1080P video)

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Short-bus</div><div class="ubbcode-body"> <object width="425" height="350"> <param name="movie" value="http://www.youtube.com/v/a4DXQaidxzQ"></param> <param name="wmode" value="transparent"></param> <embed src="http://www.youtube.com/v/a4DXQaidxzQ" type="application/x-shockwave-flash" wmode="transparent" width="425" height="350"> </embed></object>

The 175's worked fine Stefan, but I distinctly remember seeing oval's in the paper from the 168's. They didn't fare so well. </div></div>
Senility, first sign of old age.

 

[Conqueror]

Re: .308 Subsonic load testing (1080P video)

Will try and hit the range this AM to run another ladder starting at 9.5gr. It's 35 degrees outside which is about as cold as I ever want to shoot in. I don't know how some of you guys make it to the range when it's ten below, I can't even feel my trigger finger when it's that cold.