Velocity Effect of Bullet Tension

[Tiny Tim]

I am working on a load for a 243AI and I want to play with neck tension a bit. I have an accurate load with an 80 gr Hammer Hunter running about 3550fps. I'm hoping to shrink SD but was wondering if changing neck tension will affect velocity, increasing or decreasing it? Or will average velocity remain relatively constant and simply shrink ES/SD?

 

[Pmacc60]

What is the rifle twist of your barrel? I like that load your working on and I'm curious . Sorry if I went of topic but I am impressed with your numbers and bullet .

 

[Tiny Tim]

8 tw, 26" Rock Creek 5r rifling. Trying Sta-ball 6.5 @ Steve's recommendation. Hovering around .5 moa @ 300 yards

 

[Pmacc60]

Thanks!

 

[GLTaylor]

Light tension seems to slightly increase speed. Speed increase is 10-30 ft in the cartridges I've tried. SD / ES varies for some reason for me. Maybe Butterbean can comment. He's very knowledgeable.

 

[7stw]

Light tension seems to slightly increase speed. Speed increase is 10-30 ft in the cartridges I've tried. SD / ES varies for some reason for me. Maybe Butterbean can comment. He's very knowledgeable.

I have had different results, with increased neck tension, as I've seen more velocity, and lower es. My theory, is that you are holding back a little on the bullet, to get a more consistent ignition, and burn. Neck tension has always been one of my pet peeves, and I've junked a lot of brass that wouldn't give it to me. Theres a fine line on the tension issue. And threads about the use of Lee factory crimp dies have helped with that somewhat. It's a touchy subject, and has kindled a few fires here, but I can tell you in all honesty, that whether its tight, or not so tight, isn't as important, as long as its all the same
I found that most of the slow burning powders, perform better, when held back. The overall quality of your brass is key, which in turn, usually provides better, and more CONSISTENT neck tension!

 

[Tiny Tim]

Thanks. Nosler brass, turned to uniform necks, Redding bushing dies. Thinking about expanding with mandrel. Annealed after fire forming.

 

[Beluebow]

Powder charge will take care of neck tension.....pick something between 1-3 tho and run with it...testing with neck tension after you have a finished load may or may not show any improvement.

 

[Tripodmvr7]

You might have a good grouping load, but pressure with Staball might be very high at 3550fps. Reloader would be a much better call for speed and lower pressure.

 

[Tiny Tim]

You might have a good grouping load, but pressure with Staball might be very high at 3550fps. Reloader would be a much better call for speed and lower pressure.

Had this node and one a grain lower. Pressured out .7 above this one.

 

[7stw]

You might have a good grouping load, but pressure with Staball might be very high at 3550fps. Reloader would be a much better call for speed and lower pressure.

I agree 100%. StaBALL, is funny stuff. Its akin to Superformance, in fact I think it may be the same stuff. I played with it awhile back, didnt get any wheres near published velocities, even with a longer barrel, then what the loads were tested with. Then, as you creep Up on your max , it skyrockets.
Just my opinion, but another well known member here had the same thing happen with him..again, just my .02 cents.

 

[Tiny Tim]

I agree 100%. StaBALL, is funny stuff. Its akin to Superformance, in fact I think it may be the same stuff. I played with it awhile back, didnt get any wheres near published velocities, even with a longer barrel, then what the loads were tested with. Then, as you creep Up on your max , it skyrockets.
Just my opinion, but another well known member here had the same thing happen with him..again, just my .02 cents.

Yeah, saw that spike. Relatively even increase then BAM, huge jump. This is a hunting load. It would be rare to see 60 degrees F.

 

[Tripodmvr7]

I did not find any data on the Hammer projectile and used a 80 Barnes TTSX. The calculation is attached. The Ackley conversions hide pressure very well as they bind to the chamber with the small angle of taper of the case. The speed you are running at is going to burn your barrel. We have been using lathe turned projectiles for many years (circa 1990) in South Africa and they work very well.

 

[GLTaylor]

My 243AI, with 45.5 grs R16, F210, runs 3500+ with the 83 gr Hammers, no pressure and .4 groups.