.308 Savage for sub-sonic work

[NSP64]

I picked up a new Savage axis in .308 for sub-sonic workup. I have some heavy boolits coming from some board members to try before sinking cash into a mold. (everyones out of molds now anyways).
The axis .308 is on a long action and I thought maybe using a 30-06 mag to use .308 with a longer AOL. Won't work. Savage uses a trigger guard housing to take up the space between the barrel face and aft opening in the action, So, I would have to change mags AND trigger housings:(

Remington has a cheap level gun and they use spacers in aft of 30-06 mags to take up the space. (I looked).

Good news is the Savage .308 mag is roomy. I could load 3.0" cartridge AOL if the boolit fit in the barrel. I have some Lee 180gr FN boolits cast up but they are too big on the nose.(.300) and engrave the rifleing.

When the donated boolits show up I will work up some loads and post findings here.

[NSP64]

Mktacop sent me some big boolits to try
63525
63530
they look beautiful don't they..
that's a dummy round I'm using I will load them 2.984 inches long

[NSP64]

What would be a good starting point to work backwards with unique ?

[NSP64]

Headed to the range
63570
On the left is 311299 loaded 2.812
, rt is 311247

loads are 11gr trailboss and 8gr Unique

[NSP64]

Pretty good trip to the range.50 yards, new gun with 20 rounds of lee RNFP down the tube to season it.
63577
above, 247gr NOE with AL GC 8gr unique 1060 avg fps
63578
above 247gr NOE AL GC 11gr TB 1190 avg fps
63579
above 311299, 8gr U with Hornady GC, Speed green, 1150 fpsa
63580
above 311299, no ck, 8g U, speed green, 1150 fpsa
63581
above 311299, GC , 11gr TB, speed green 1250 fpsa
63582
above 311299, no ck, 11gr TB, speed greeen 1250 fpsa

Next time I will drop the charges, All hole looked round.

[uscra112]

Work down from about 10 grains of Red Dot. Somewhere about 8.0 you should be subsonic. I've tried this kind of load in almost every cartridge I load. Nothing beats Red Dot. Ed Harris knew what he was writing about. The 10 twist may getcha at some point, so be willing to drop back to the a 180 grain like the 311041. Use a pistol primer to minimize shoulder setback.

[Bulltipper]

uscra112, what is "shoulder setback"? Pardon my ignorance, I load and shoot a lot of .308 subsonics, and I am very interested in anything I am not familiar with!

[Artful]

When shooting lower pressure rounds, the force of the primer igniting is pushing against the bolt face which the high pressure in the primer pocket in turn forces the case forward. This of course doesn't happen with rimmed cartridges which head space on the rim or Belted either.

The pressure of the load isn't powerful enough to force the case back reseating the primer and blowing the should back to normal dimensions. Thus the shoulder is set back from where it started.

Another possible cure is to enlarge the primer pocket flash hole letting more of the pressure escape more easily thus not allowing the primer to push out of the case.

The other thing is to set the Boolit all the way into rifling hard enough that the case can't go forward.

Should set back can also happen if you mis-adjust your reloading dies
http://www.shootersforum.com/attachments/handloading-equipment/10583d1322853373-best-way-clean-brass-shoulder-setback.gif

All of this has a direct effect on headspace of the cartridge in the chamber.

[Bulltipper]

Thank you Artful, you seem to be there for me regularly! Now I have to ask, since my subsonic brass is always reused as subsonic, and I use LC match for thier lower volume case and the thicker wall it provides, should I enlarge all my subsonic cases in the flash hole and should I always use pistol primers?

[Artful]

I have cases I separate that have enlarged flash holes - make sure you mark them in some way - I use marker in the extractor groove and color the head.

You can also buy some cases of a brand you never use and do that to them to help ID 'em.

Now having said that - unless you have a load worked up already you can try different primers - even changing from one maker to another in Large Rifle primer can make a difference - when you get down into the low power end of things - the little changes can make much larger differences.

[uscra112]

Haven't done the detail study with .308 yet, (I don't have a .308 of any kind), but my careful measurement of 5.56 / .223 brass and .30-06 brass showed that the idea that military brass is heavier/thicker/less-capacity is a myth. On average commercial brass was just about the same as LC and Federal milspec brass. Only exception was one offshore military supplier whose headstamp I didn't even recognize, and of which I only had about a dozen cases in the sample.

My low-power loads for .30-06 and 7.5x55 do the "jam the boolit into the lands" solution. It seems to give more consistent accuracy. Haven't studied the velocity variance of either load yet.

[NSP64]

A great day
66577
Lee 230 gr boat tail, sized .310, speed green lube, 9.2 gr TB, 1020 fps average, 30 fps spread. Three shots @50 yards.
Tomorrow I will go back to 100 yrds.
And the wind was blowing 23 mph right to left.

[Jim]

66578

Developing subsonic loads for centerfire rifles. (http://floydpics.wordpress.com/developing-subsonic-loads-for-centerfire-rifles/)

[NSP64]

Jim, that's a good target.
2.8 looks promising.
do you tilt the powder back to the primer?