Subsonic issues

[GardDog]

I gleaned the following loads from the Subsonics section of the Reloading Depot. I tried to use recommended loads from shooters that had a weapon similar to mine.

Here's the conditions:
Temperature - 90 degrees
Pressure - 29.99
RH - 79.7%

Here's the gear:
Rem 700P .308, 26" barrel, 1-12 twist

My results:

<span style="text-decoration: underline">Hornady 180 gr RN - 9.6 gr TB</span>
Lo - 679.3
Hi - 806.7
Av - 758.68
ES - 127.4
SD - 56.30

<span style="text-decoration: underline">Hornady 180 gr RN - 9.8 gr TB</span>
Lo - 649.0
Hi - 776.6
Av - 702.9
ES - 127.5
SD - 46.59

<span style="text-decoration: underline">Lapua SS 200 gr - 10.0 gr TB</span>
Lo - 645.6
Hi - 753.5
Av - 677.4
ES - 107.9
SD - 44.49

<span style="text-decoration: underline">Lapua SS 200 gr - 10.2 gr TB</span>
Lo - 692.6
Hi - 765.5
Av - 726.6
ES - 72.93
SD - 30.28



1. Why is my version so far from the sonic edge?
2. How much do you think I should bump the loads to get near 1050 fps?

 

[coldbeerchief]

Re: Subsonic issues

Hornady 180 gr RN - 9.6 gr TB -> Av - 758.68
Hornady 180 gr RN - 9.8 gr TB -> Av - 702.9

did you notice that average velocity decreased with increased powder? This could be due to fouling in the bore. TB is dirty, cleaning the bore between strings will yield more uniform results for comparison.

Try 12 grains of TB and work down from there.

 

[GardDog]

Re: Subsonic issues

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Insert Name Here</div><div class="ubbcode-body">TB is dirty, cleaning the bore between strings will yield more uniform results for comparison.

</div></div>

After each 10 rounds, I would run a bore snake through the barrel.

Thanks for the advice. I was wondering how high I could go with TB in a .308. I heard some crunching with the 10.2 and was worried about reaching max capacity for my length.

 

[Fritzcat]

Re: Subsonic issues

I copied the load that others had good results with.
Horn 180gr 10.5gr TrailBoss
I do not have the Data here, but it will be 1050 to 1100.
My 20" Shilen 1x10 can get 1 MOA most of the time.

 

[ChadTRG42]

Re: Subsonic issues

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: GardDog223</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Insert Name Here</div><div class="ubbcode-body">TB is dirty, cleaning the bore between strings will yield more uniform results for comparison.

</div></div>

After each 10 rounds, I would run a bore snake through the barrel.</div></div>
A bore snake is not cleaning a rifle. I consider a bore snake something you use if you drop your rifle muzzle down in the mud and need to get the mud out.

 

[howdydoodie]

Re: Subsonic issues

Garddog keep me informed I will be loading up some of the 180's and Lapua's here in a couple months. Are you getting stabilization, any "keyholes"?

 

[LARMIKE]

Re: Subsonic issues

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ChadTRG42</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: GardDog223</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Insert Name Here</div><div class="ubbcode-body">TB is dirty, cleaning the bore between strings will yield more uniform results for comparison.

</div></div>

After each 10 rounds, I would run a bore snake through the barrel.</div></div>
A bore snake is not cleaning a rifle. I consider a bore snake something you use if you drop your rifle muzzle down in the mud and need to get the mud out. </div></div>

Kinda hard to push the dirt out with a string ????

 

[shooter308]

Re: Subsonic issues

i use 8.7 gr with 165 gr rem acutips in my 308 and worked all the way up to 9.1 then straight up to 10. 10.0 gr was way too loud. I set out a 3/4 thick oak board at 75 yards and shot a 165 acu-tip through it at 9.1 gr which is still louder than the 8.7-8.8 gr i went with. And it went all the way through without expanding and blowing up so i figured this is good for deer with this kind of fast expanding bullet

 

[shooter308]

Re: Subsonic issues

sorrry Trailboss was the above load listed but i made sure all bullets exited my 22 in bbl'd 308 before the next shot. The test was done one week ago

 

[GardDog]

Re: Subsonic issues

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: howdydoodie</div><div class="ubbcode-body">Garddog keep me informed I will be loading up some of the 180's and Lapua's here in a couple months. Are you getting stabilization, any "keyholes"? </div></div>

No keyholes, just not enough speed, yet. I will be loading the next set later today & testing them Monday, if the rain holds off. I'll post after I get more downrange.

I'll also clean the barrel after each string, instead of after every 10 shots.

 

[howdydoodie]

Re: Subsonic issues

Thanks GardDog I bought 500 of the Lapua SS I am hoping that they were worth the money. Good luck.

 

[GardDog]

Re: Subsonic issues

Rained out this morning. Hoping that Saturday is dry enough to shoot.

 

[GardDog]

Re: Subsonic issues

I finally had a day to shoot where it wasn't raining. I upped the Trailboss to 12.0 gr for one string and 12.2 for another string with the Hornady 180 gr RN. I upped the TB to 12.2 and 12.4 with the Lapua 200 gr LSS. I cleaned the bore after each string.

Rem 700P, 26", 1/10 twist

Pressure = 29.97
Temperature = 80.6 degrees
Humidity = 86.3%

Error issues with the 12.0 gr load.
The 12.2 gr of TB with the 180 gr RN averaged 1057 fps.
The 12.2 gr of TB with the Lapua 200 gr LSS averaged 1023 fps.
The 12.4 gr of TB with the Lapua 200 gr LSS averaged 1064 fps.

I moved the target in to 50 yards and had no keyhole issues, all clean passes. I still have some room to play to get close to the sonic edge.

 

[howdydoodie]

Re: Subsonic issues

Is 50 yards the longest distance that you shot? Those #'s look good to me. Thanks for the update.