308 subsonic

[mosigdude]

Ok, I finally got my chrono up and running again and had a chance to run out to the range. I've abandoned the altered cases for the time being so I have no new follow-up on that. I did, however, get a chance to play some with the Titegroup loads. Two parts of this testing were very promising, the other was somewhat perplexing. First, the load info:
6.8 gr (20.9% case capacity) - 8.0 gr (24.5% case capacity) of Titegroup loaded in 0.2 gr. increments in an unaltered standard RP 308 case, Fed 210 LR Primer, 168 gr. Sierra Matchking, 2.800 OAL. The rifle is the same as other tests I have done, Remington 700 Tactical, 1/10 Twist, 20" BBL.

Velocities ranged from 1078 ( 8.0 gr.) - 883 (6.8gr) FPS. Extreme spreads per loading were VERY low and averaged around 12 FPS. Accuracy was excellent at MOA or less on each load... No pressure signs in any fired cases. In other words, Titegroup is the wonder-powder that I've been looking for in this caliber, it does not seem to be at all sensitive to position, even with less than 1/4 of the case filled. If this was the end of the story, I'd make this post and resign from this thread forever... but of course, it never really works that way.

Here's the mystery...

I have shot similar loads, same case/projectile specs (2.800 OAL, 168 Sierra Matchking, RP Case, etc.) I have not even changed my loading die settings (although I verify at the beginning of each loading session) since my last test of this bullet/rifle combo. The only difference in earlier loads was a diff type of powder. Even though they lacked the consistency of this load, I have shot individual rounds that have clocked velocities in this same range. Until today, none have key-holed. Almost every round today showed some evidence of key-holing. None of them impacted completely sideways, but I can see marks from the rifling on the target from several of the hits.

Has anyone else had this happen or have any ideas? Same bullet at the same velocities but with two different powders, one key-holes, the other doesn't?!? I'm stumped.

The obvious solution in this particular gun is to change bullets, either design or a lighter weight. I'm just curious what could cause this.

Until next time...

[Scoop]

Originally Posted by mosigdude

Here's the mystery...

I have shot similar loads, same case/projectile specs (2.800 OAL, 168 Sierra Matchking, RP Case, etc.) I have not even changed my loading die settings (although I verify at the beginning of each loading session) since my last test of this bullet/rifle combo. The only difference in earlier loads was a diff type of powder. Even though they lacked the consistency of this load, I have shot individual rounds that have clocked velocities in this same range. Until today, none have key-holed. Almost every round today showed some evidence of key-holing. None of them impacted completely sideways, but I can see marks from the rifling on the target from several of the hits.

Has anyone else had this happen or have any ideas? Same bullet at the same velocities but with two different powders, one key-holes, the other doesn't?!? I'm stumped.

The obvious solution in this particular gun is to change bullets, either design or a lighter weight. I'm just curious what could cause this.

Until next time...

The problem is the 168 SMK's. They tend not to fly very well at subsonic velocities. Also, changes in environmental conditions can wreak havoc on bullets that were just barely stable to begin with. Are you sure your Remmy is a 10-twist? I've never had the 168's to not yaw in flight from a stock Remmy (they are usually 12-twist). They are just not a good bullet for subsonic loads. Makes you wonder why Hodgdon has them listed in the only two subsonic .308 loads on their website. You want the shortest bullet you can load in the weight class you're looking for. Stick with round nose or flat nose stuff. They work better simply because they're shorter.

[Artful]

Or try loading the 168's backward. Dr Dater (Gemtech) is against using boattails in subsonic loadings for suppressors due to what your are experiencing.

[mosigdude]

Yes, I was sure that I had a 1/10 twist... that is, until I checked it today... it is most definitely a 1/12!?! Go figure! I was positive that it was a 1/10 and I have no idea where I got that info, obviously from a bad source, probably myself.

I'm going to play with some stubby 150's and see how that works out. As I said in the beginning of this, I really have no actual need for this load since supressors are banned in MO, but still it's fun to play with the loadings, I guess I just got bored with the usual load work-ups. Anyhow, I'm not sure if there is anything out there, but I'm going to see if I can find a 150 FP or HP with a little lead exposed to get a little expansion started at sub velocities. I'm definitely going to continue to work with the Titegroup powder, that stuff is amazing in its lack of positional sensitivity! I'll post updates as I have them.

Thanks to Scoop and Artful for the added info!

[Scoop]

Originally Posted by mosigdude

Yes, I was sure that I had a 1/10 twist... that is, until I checked it today... it is most definitely a 1/12!?! Go figure! I was positive that it was a 1/10 and I have no idea where I got that info, obviously from a bad source, probably myself.

I'm going to play with some stubby 150's and see how that works out.

Anyhow, I'm not sure if there is anything out there, but I'm going to see if I can find a 150 FP or HP with a little lead exposed to get a little expansion started at sub velocities.

Just pick up some of those Berry's 150 gr plated bullets I talked about in post #86 of this thread. Load 'em up and enjoy. They work well in the 12-twist barrels and they are cheap.

Pretty sure you're not gonna find a rifle bullet that will even begin to expand at 1000 fps. You'd have to go to specialty stuff to get any kind of performance at those velocities. Wonder if Berry's or Ranier would consider making a run of their plated stuff with a hollowpoint profile and a super soft alloy core? Might have to call and see.

[mosigdude]

I'll definitely give them a try, I'd be interested in a soft lead HP version of that as well. There seems to be a lot of interest in this forum in a 30 cal rifle bullet that will expand at these velocities. I'd guess if someone made a plated HP in the 150-165 gr range and another in the 200-220 gr range they'd have the market cornered and this should work fairly well for the full range of rifling twists. Maybe a couple phone calls wouldn't hurt.

In the mean time, I'm going to start brainstorming on constructing some kind of punch/swage to convert a few of those Berry's Plated 150's to a HP configuration with a bit of consistency... maybe something I can turn out on the lathe that will fit in a standard reloading press, how hard can it be?

[cearick]

I used 8 grs of Trailboss topped of with a 168 gr matchking. Works great out of a 20in 700.

[mosigdude]

I sent a message to Berry's about the possibility of producing a plated HP in the 150 gr range and another in the 200-220 gr. range. It looks like there may be some hope for the idea from his response. See details in the ammo section of this forum.

And it looks like MO is going to legalize supressors effective Aug. 28th. Of course all the federal requirements will still apply, but MO will no longer specifically prohibit them, so I'm ready to get this figured out!

[oneshot]

It is interesting to see that others have experimented with lead as a filler. My approach was slightly different. I filled the case with molten lead up to the base of neck (using a toothpick to block the flashhole), then drilled a 6mm hole thru to the flashhole. Finally, use a 7.5mm drill to "even out" all the shells, and make room for bullet seating. In effect, you get an "even" cavity from primer to bullet base, and the lead stays put , held in by the shoulder!

[GlockandRoll]

Originally Posted by cearick

I used 8 grs of Trailboss topped of with a 168 gr matchking. Works great out of a 20in 700.

I would have assumed it would be a problem due to the length of the bullet...
what's the rate of twist, and what velocity where you pushing?