Need a subsonic load please

[Surgeon_Shooter]

Hey guys,I should be getting my AAC cyclone soon and im gonna start working on a sub sonic load for it.It has a 20" barrel and a 10 twist .308.What size bullet and what type of bullet? What powder and about how much?

Thanks

JAY

 

[xringdb]

Re: Need a subsonic load please

Jay,

The Hornady 180 gr. RN is a good bullet to try. It has a stability factor of 3.42. A factor of 2.0 or higher is recomended for SS use.

I got the following velocities with Trail Boss powder in an 18" Broughton 5C, 1 in 11 twist barrel with this bullet.

Lapua brass with the flash holes drilled to 9/64", F215M primers.

11.0 gr. = 1075 fps.
10.5 gr. = 1015 fps.
10.0 gr. = 975 fps.
9.8 gr. = 950 fps.
9.6 gr. = 920 fps.

I would recomend you do your initial testing without your suppressor attached. Looking for nice clean holes in your target at 50 yds. If your loads are cutting clean round holes in your target you will know they are stabilized and a baffle strike is not a danger.

I have tested several bullets and the Hornady 180 gr. RN was the easiest to get to shoot well in a the two different .308's I used. It shoots sub MOA in my 1 in 11 twist. I have shot it out to 250 yds. with good accuracy.

Hope this helps and have fun.

 

[bohem]

Re: Need a subsonic load please

http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=468230#Post468230

 

[Surgeon_Shooter]

Re: Need a subsonic load please

Thanks guy this is very helpful,Ive been reading around and im about half ass scared to try loading ss loads because of SEE.From my understanding if i drill the flash hole out and NOT get below 30% case capacity i should be ok.Is there any thing else to watch out for in this case?

Thanks

JAY

 

[bohem]

Re: Need a subsonic load please

I think you don't have anything to worry about if you keep those things in mind.

Trail Boss will negate the SEE problems because it's so light and fluffy that you'll get about 80% case fill.

If you don't want to use TB because it's not available or expensive or whatever, you can make reduced capacity cases with epoxy or solder.

I've used several methods, and having some reduced capacity cases on hand to load something like Red Dot or Unique is pretty handy.

 

[JL]

Re: Need a subsonic load please

Vihtavuori N310.

bullets around 175gr, start load 5,4gr. Go slightly up or down depending velocity. My load is 6,2gr with 168gr moly Scenars.
Normal primer. No need fo drilling flash holes or fillin cases.

use only molycoat bullets -or even better, lead with grease.
Othervise copper fouling may cause too much MV variation- or even jam bullet near muzzle.

You can also try to load bullet backwards, better BC in subsonic flight.

 

[bohem]

Re: Need a subsonic load please

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: JL</div><div class="ubbcode-body">Vihtavuori N310.

bullets around 175gr, start load 5,4gr. Go slightly up or down depending velocity. My load is 6,2gr with 168gr moly Scenars.
Normal primer. No need fo drilling flash holes or fillin cases.

use only molycoat bullets -or even better, lead with grease.
Othervise copper fouling may cause too much MV variation- or even jam bullet near muzzle.

You can also try to load bullet backwards, better BC in subsonic flight.
</div></div>

I think you're the first person other than me that's said to reverse the bullet. Cast lead is my solution to this dilemna as well.

EDIT: I missed the "better bc" comment, I advise for it for loads on the margin of stability. It doesn't help BC at all. If it did, airplanes would have flat noses.

 

[coldbeerchief]

Re: Need a subsonic load please

Those VV N310 loads seem a bit light to me.

My N310 load is 8.1 gr. for 1045 fps out of a 16", 10-twister with 175 SMKs.


Also, loading the bullet backwards aids stability, while making the BC worse-not better

 

[JL]

Re: Need a subsonic load please

S-S, forgot to mention: when testing new subsonics loads, cleaning rod might be needed. For tapping out stuck bullets.


Especially some bullets, like Lapua Lockbase, D46/D47 etc has dimple in base bottom. So basically base is round, not flat.
Since drop form is optimal for subsonic flight drag, and bullets are closer to that shape backwards, I presume it should/must be better. Dont have any data tho.

I wonder what Litz thinks about it...