Velocity Effect of Bullet Tension

[nksmfamjp]

Here's my take....I think neck tension has zero impact on bullet release. I think that the powder charge is blowing the case walls out to touch the chamber before enough pressure to move the bullet has occured.

At high neck tension, I find the bullet is deformed by my seater which could hurt things.

 

[david g ranes]

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!

David tubs he seats 10 thou into the rifling and don't worry about neck tension any body tried it. David

 

[budlight]

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 get the same speed with 80 gr spbt win standard Win 243 with about 48 gr of superformance and easy on the cases. 26 inch rem sps varminter and 2 inch brake. Superformance is really a nice powder for middle weight 243. I've worked up some Ramshot hunter and R-23 for 80 - 87 gr in the past

IMO - distance to the lands has a greater effect than neck tension. I use the redding comp die set then neck inside and outside neck turn

 

[Savage 12BVSS]

I've found that using a mandrel to keep neck tension consistent is good for accuracy, brushing the necks but leaving some carbon in them is important as well. As STW said, its all about consistent loading technique and my experience has been distance off lands, and powder charge are important tuning tool's, but neck prep and sizing does some of the real fine tuning. Just my experience mind you

 

[Tiny Tim]

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.

Thanks for your reply. I wish I understood QL better. If I'm reading it correctly, your printout shows a load of 52 gr to obtain this velocity and at a compressed load. I am nowhere close to that. I understand the Ackley cases "hide" pressure better than standard, but my primers are normal for such a load, I have typical case head expansion, zero brass flow (ejector swipe), primer pockets are tight, and am still able to neck size only without trouble chambering. I went back and looked over all my cases and data after reading your reply. I am grateful to men like you who have the skills to utilize such technology and share genuine concern. . It may save someone's life, maybe even mine someday. Thanks again!

 

[baldhunter]

Some things about brass to think about.New brass is soft.After several firings it starts to harden.Several things can start to happen.When seating bullets into harden brass it can cause more run out.It can also affect neck tension too.

 

[budlight]

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.

QL is a good tool to get you in the ball park. QL and chronographs always seem to have some variations. When QL first came out they just didn't have enough data. There are just so many variations from age hardening of a copper bullet to the actual barrel. I've hand lapped barrel burner type rifles to keep the number of rounds down and no break in period. Polished SS barrels are slick enough to require more powder to get the same velocity. I also saw this when I was moly coating bullets. I know 243 and the AI are barrel burners because of overbore case capacity. That's why I stayed at 243 win.

 

[406precision]

There is definitely a correlation between velocity and neck tension..the more tension the more pressure I believe the guys at Barnes have played with this extensively

 

[7stw]

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

I love RL16. My 7-08 loves it, 6.5cm loves it with 140 class bullets. That stuff I would think might be the fairy dust in a 243ai. I've became a AI fan myself recently, which is a different story, but the OP is questioning neck tension, and its benefits, or difference.

 

[James DeTorre]

Need a tutorial on neck tensioning. Somebody have a source?

 

[406precision]

Need a tutorial on neck tensioning. Somebody have a source?

Please excuse my spelling but Eric Cortina i believe has done some youtube videos on it

 

[epoletna]

I second James DeTorre's query -- tutorial on neck tensioning would be much appreciated.

 

[WahooYahoo]

21st Century Shooting has an arbor press for seating with a gauge to reflect seating pressure. One could sort their load based on seating pressure (neck tension) and see the real difference it makes down range

Hydro Bullet Seater

21st Century Shooting, Reloading products, Reload, reloading ammo, 21st century, twenty first century shooting, shooting, gun reloading, hydro bullet seater, tools for reloading, front rest, f class, bench rest, short handle, arbor press, powder measure, bullet, bullet comparators, die base...

www.xxicsi.com

 

[nicholasjohn]

Thanks for your reply. I wish I understood QL better. If I'm reading it correctly, your printout shows a load of 52 gr to obtain this velocity and at a compressed load. I am nowhere close to that. I understand the Ackley cases "hide" pressure better than standard, but my primers are normal for such a load, I have typical case head expansion, zero brass flow (ejector swipe), primer pockets are tight, and am still able to neck size only without trouble chambering. I went back and looked over all my cases and data after reading your reply. I am grateful to men like you who have the skills to utilize such technology and share genuine concern. . It may save someone's life, maybe even mine someday. Thanks again!

Tiny Tim,

What do you mean by "typical" in regards to case head expansion ? Also, what is your method for measuring this ? I have found this to be a very tricky thing, and a lot of guys don't measure it for that reason. I think it is a very good way to find where maximum pressure is, but there are so many techniques out there that I have to wonder if you've got a better method. I do use a blade micrometer, and have devised a method for measuring the same spot each time. I would like to get your input on how you do it. How about messaging me about it, so we don't goof up this thread by going off-topic ? Thanks.


Nick