.308 Bullet stability experiment.

[markm87]

My buddy bought some 220 grain Sierra Hunter bullets... (not knowing that they were completely useless for the shooting we do) There a round nose, soft point, Flat base with a silly low B.C.

So I got the notion of making thumper Sub Sonics out of them. They're a pretty long bullet for .308 and thus were not stabile (my barrel is 1/12). No key holes but horrendous accuracy and yaw holes. About 8-9 MOA with a lot of vertical strining at 100 yards.

Seeing that, I set out to confirm that Higher RPMs would do little to improve this mis-match barrel/bullet. But to my surprise 39 grains of Varget made them shoot stabile and about MOA with relatively rapid fire.

 

[mao0720]

Did you happen to chrono both loads?

 

[markm87]

In classic fashion. I didn't remember my Magnetospeed. I'm estimating 1000 and 2500 FPS respectively....

 

[mao0720]

What was your first charge weight? Just curious, as I had a recent experience with my AR15 not stabilizing 68gr Hornady HPBT and I am trying to decide whether or not I want to try to hot up the load to to try to get them to stabilize.

 

[gary0529]

Markm,

Just a question. If you are expecting the 220 gr to open up at subsonic speeds you might be disappointed.
In my quest over the years to get a good deer smacking 300 Whisper round (aka 300 BLK) and not have to use the high priced hand made Lehigh or Outlaw State bullets-both work VERY well on deer at under 1100 fps- I contacted all the major bullet makers and no one says theirs will open at subsonic speeds--not a one!

Unless you can assure a clean head or spine shot I will most assuredly tell you that the Sierra 220, 240 and A-Max 208 gr Hornady will not open one bit subsonically.

A chest shot will mean a long long walk to trail the deer if you severed a large vessel-almost no blood trail to boot. The one I did shoot did die, 1 mile later and the round fully penciled thru the chest.
Never again with that combo.

The Lehigh and Outlaw bullets will however work very well on chest shots, akin to most other supersonic soft pointed rounds.

Just my experience on taking a number of cull deer with the subsonic 308

Gary