subsonic questions

[gebhardt02]

I've been working up some subsonic loads, and they seem to be doing OK, but I have some questions regarding stability. The loads are 308, LC 99 LR brass fully prepped, 220 gr RNSP bullets, 11 gr Unique, 210M, getting 1077-1124 fps over 11 rounds, Krieger 11 twist. I know the twist is on the slow side, but wanted to see how these bullets would do anyway.

My question is that at 200 yd, I'm not exactly getting what I would say is keyholing, but a very slightly opened up hole in paper. Not every shot, but about half, where it looks like the bullet is on the edge of stability. I've not fired these through the can yet, but wondering if I should just scrap the loads and go with a lighter bullet or if this is somewhat normal at 200yds. The paper was stapled to plywood. I noticed a little bit of the same impacts at 100, but thought it might have been something else. What are your suggestions? TIA

Geb

 

[DustyJacket]

Re: subsonic questions

Put some target closer (10 feet, 20 feet, 30 feet) and see if you get signs of wobbling.

If they wobble coming out of the muzzel you are going to get baffle strikes.

Wobbling 200 yards down the road are less serious.

 

[bohem]

Re: subsonic questions

You might be wobbling, you should try what DJ said above. Also, the CM and CP of supersonic bullets is stable in one direction at supersonic speeds and flipped at subsonic speeds.

Unless you shoot a faster twist with something that's bordering on unstable you won't be able to get them back. However, if you load them backwards in the case (IE, seat the nose into the case) they are much more stable.

Also, you will probably have better results with RN bullets than spire points because of this issue.

 

[LARMIKE]

Re: subsonic questions

Try the 18gr. Hornadys. Much better accuracy. We were able to get very good groups out to 300. The 220gr. dont like the 1-11 twist. I had a 1-8 that they shot pretty good in.

 

[wksinatl]

Re: subsonic questions

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: LARMIKE</div><div class="ubbcode-body">Try the <span style="font-weight: bold">18gr.</span> Hornadys. Much better accuracy. We were able to get very good groups out to 300. The 220gr. dont like the 1-11 twist. I had a 1-8 that they shot pretty good in. </div></div>

I'm sure he means the 180gr Hornady which is also what I use.

Keith

 

[malaga2]

Re: subsonic questions

I would also move away from the 220's with a 1:11. I also really like the 180 rn both in a 1:10 and 1:12.
On the spire point issue Im not sold on that as my most accurate loads with any subsonics were with Sierra 240 match kings through a 1:8 Whisper...
The RN bullets are a hell of a lot cheaper though....

 

[DustyJacket]

Re: subsonic questions

I just went from a 1:10 to a 1:12 twist (now 20" bbl)

What are some good subsonic recipes? I am planning on the 180gr RN bullets.

 

[Fritzcat]

Re: subsonic questions

I also like the 180gr Horn with 10.5gr Trail Boss, it nearly fills the case. I have loaded 1 batch with 220 Horn Rn with 13gr Trail Boss, but did not goup as well. I load the Horn 220 Rn for my AR47 7.63x39 with 9.5gr Win 296. shoots OK at 100yds. like it for Hog Hunting. Even though I have not used a sub-sonic on a hog yet. I have used Universal Clays and Unique but like the Trail Boss because it fills the case and I have a 5# jug.

 

[robpiat]

Re: subsonic questions

I concur on the 180 Grainers...I use the sierras which are similar...

I just got a 300 whisper, so my interest in tinkering with the 308 dropped off.

 

[bohem]

Re: subsonic questions

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Malaga2</div><div class="ubbcode-body">I would also move away from the 220's with a 1:11. I also really like the 180 rn both in a 1:10 and 1:12.
On the spire point issue Im not sold on that as my most accurate loads with any subsonics were with Sierra 240 match kings through a 1:8 Whisper...
The RN bullets are a hell of a lot cheaper though.... </div></div>

The backwards spire point fixes instability problems when things are marginally stable. If you're shooting a 1:8t nothing's marginally stable so you don't see that problem.

A 1:11t barrel isn't a high enough twist to run the heavies that slow, hence the advice given.

Just to clarify my advice.

 

[cinosbus]

Re: subsonic questions

Anybody shooting a 170gr flat point, like a .30-30 bullet?

Seems like the terminal effect would be better with a flat or hollow point. A half jacketed hollow point would be ideal.

 

[ggarrett1911]

Re: subsonic questions

Yes, I prefer the 170 Hornady flat points for subsonic hunting purposes. I shot a deer (kill permit hunting on a cantaloupe farm at night) with one a couple weeks ago from approximately 140 yards, hit her in the neck & broke it (DRT), bullet passed through completely. Sounded like somebody hit her upside the head with a 2x4 when that bullet slapped her. I actually chrono'd some sub loads with this bullet & 10.2 grains of Trailboss yesterday, in 90+ degree heat they were checking out of my 16" barreled Savage with SAS can @ 1090 FPS.