Controlling Neck Tension

[Dusty Stevens]

If it varies more than .0001 on one side or the other they need to be turned

 

[Frankr]

If it varies more than .0001 on one side or the other they need to be turned

Dusty did you mean .001 ?
Because I have turned a lot of necks and the best I could ever get using a ball mic is .0003
Have I been doing something wrong?

 

[dkhunt14]

Dusty did you mean .001 ?
Because I have turned a lot of necks and the best I could ever get using a ball mic is .0003
Have I been doing something wrong?

You should be able to hold .0001 when turning. Once in a while you will get one that is off. Matt

 

['Freak]

I tried a .266 bushing
After I ran the brass thru the die I would end up with a .239 inside neck dia. ?
Using .243 bullet that leaves me with a -.004 neck to bullet interference fit, way to tight.
I ordered both .268 and .267 bushings to try.

Curious; what’re you using to measure case neck inside diameter?

 

[JRS]

A telescoping gauge or hole micrometer will give you the inside dimension.

 

[dmoran]

I tried a .266 bushing
After I ran the brass thru the die I would end up with a .239 inside neck dia. ?
Using .243 bullet that leaves me with a -.004 neck to bullet interference fit, way to tight.
I ordered both .268 and .267 bushings to try.

There is as good of chance that 0.004" neck tension could be optimal as could a lighter tension.

OK
After I measure the neck what's the standard deviation that determines if you need to turn the neck ?

If you want consistent neck tension from bushing dies, I strongly suggest to neck turn.
No turn works fine with expansion and collet type setups, but is not a good way to approach reloading for neck consistency from bushing dies.
Donovan

 

[500Stroker]

Curious; what’re you using to measure case neck inside diameter?

All I got is a digital calipers, looks like I need to upgrade.

 

[500Stroker]

There is as good of chance that 0.004" neck tension could be optimal as could a lighter tension.




If you want consistent neck tension from bushing dies, I strongly suggest to neck turn.
No turn works fine with expansion and collet type setups, but is not a good way to approach reloading for neck consistency from bushing dies.
Donovan

The reason I built this "no turn BRX" rig is because I had a bad experience turning necks for my Dasher and no longer want to be involved with it and still dont. Please provide an example of a "expansion and collet setup" I think I know what you mean but I want to make sure.

 

[dmoran]

500stroker -
If I myself was planning on running a no-turn 6BR-Improved, I would setup with dies that use expander balls/buttons to set the neck. And would use tapered carbide buttons, so that I would not need to lube the inside of the case neck, so that I would not have to clean out the cases before charging them.
Donovan

 

[Dusty Stevens]

All I got is a digital calipers, looks like I need to upgrade.

You need what is called a tubing mic. Sinclair sells them from mitutoyo. Then you should get a machinist to give you some pointers on using them as they are very touch sensitive. Takes lots of practice to get repeatable readings. Don nielson makes a rig that measures with a dial indicator so it takes touch out of the equation and may work better if youve never used a mic much.

 

[Dusty Stevens]

Here is an article from this site on measuring necks and shows lots of options including the neilson one at the end

http://www.accurateshooter.com/technical-articles/case-neck-mics/

 

[Brians356]

All I got is a digital calipers, looks like I need to upgrade.

You said a mouthful. Calipers are useless unless you can accept plus/minus .001" at best. Try measuring diameters of some pin gages some time, with a caliper and a good 1" vernier micrometer, you might just feel like tossing the caliper. Even my expensive Mitutoyo caliper is lame compared to a micrometer.

Neck bushings are often not really as marked. I determined most Redding neck bushings are ~half a thou smaller than marked, some nearly a whole thou smaller.

But of course an outside mic cannot measure inside holes. I use a set of "minus" pin gages, but those are in increments of .001", so all I can do is use those for no-go gages in bushings, and estimate the in between size from the wiggle.

You could use JB Weld to make casts of your bushing orifices, then measure the casts with a micrometer. Cerrosafe would work too, of course. As GSXR mentioned, the real way is to use a telescoping gauge or hole micrometer. But bottom line is don't just blindly trust your bushings' marked sizes.

 

[Brians356]

Here is an article from this site on measuring necks and shows lots of options including the neilson one at the end

http://www.accurateshooter.com/technical-articles/case-neck-mics/

One problem with simple tubing micrometers is that unturned case neck walls are tapered thinner towards the mouth, so you need some sort of depth stop to take all measurements around a neck circumference at the same distance from the case mouth. Any of the tools shown which have a built in depth stop will be good. I made my own adjustable depth stop for my Mitutoyo tubing micrometer.

 

[halfmoanut]

If you measure 10 bullets that are 243.4 at the pressure ring and you seat them in 10 cases and you take a measurement on the outside of the neck you will get a idea how uniform your Lapua brass is, if it varies more than .0003 I would skim turn all of it. If the loaded round is consistent no need to turn necks. The other way would be to buy exact pin gauges to see how consistent the necks are. Why people turn necks is because you are at the mercy of each lot of brass you purchase that it all measures the same( good luck) If you purchase a quality ( PMA turner, Don Nielson( pumpkin) you will have no problem turning necks to quality dimensions.P.S. You need quality measuring tools.

 

[HTSmith]

Back when 600 yds bencherst started. A group of us were shooting 6BRX NO-Turn necks, not turning necks and setting records. The 6BRX I shot 3 IBS 600yds records with, was a 0.271" neck, I run a 0.267 bushing. Don't fool with turning neck. I was 0.015" into the lands. I wanted enough grip for the bullet not to move. Start with a 0.267" and be sure you have a good chamfer on you necks with a VLD reamer. 33.5 gr is a stiff load of Varget, may be your primer problem. Get your speed at 2975 f/s, that is the best speed for the 105 and 108 Berger. any faster is not needed. The 6BRX can run 3100 + but I have had 5 - 6BRX barrels, they all shoot at 2975 f/s.

Mark Schronce

MarkS, Feb 22, 2016 Report

Setting records without turning necks or annealing? How can that be?

 

[500Stroker]

Back when 600 yds bencherst started. A group of us were shooting 6BRX NO-Turn necks, not turning necks and setting records. The 6BRX I shot 3 IBS 600yds records with, was a 0.271" neck, I run a 0.267 bushing. Don't fool with turning neck. I was 0.015" into the lands. I wanted enough grip for the bullet not to move. Start with a 0.267" and be sure you have a good chamfer on you necks with a VLD reamer. 33.5 gr is a stiff load of Varget, may be your primer problem. Get your speed at 2975 f/s, that is the best speed for the 105 and 108 Berger. any faster is not needed. The 6BRX can run 3100 + but I have had 5 - 6BRX barrels, they all shoot at 2975 f/s.

Mark Schronce

I annealed all my fire formed brass and after trying different bushings and expanders I got the neck tension down to .002
Using Berger 105's just on the lands and a health amount of Varget I shot my first 5 shot test loads today and ended up with one group at 1/4 moa @ 100 yards all groups were smaller than 1/2 moa. No turn necks.
With some more tuning, I think I am headed in the right direction.
No more punched out primers

 

[Dusty Stevens]

One problem with simple tubing micrometers is that unturned case neck walls are tapered thinner towards the mouth, so you need some sort of depth stop to take all measurements around a neck circumference at the same distance from the case mouth. Any of the tools shown which have a built in depth stop will be good. I made my own adjustable depth stop for my Mitutoyo tubing micrometer.

If you dont get the exact same measurement anywhere on the neck you need better neck turning tools. No need for stops or anything like that

 

[dkhunt14]

Back when 600 yds bencherst started. A group of us were shooting 6BRX NO-Turn necks, not turning necks and setting records. The 6BRX I shot 3 IBS 600yds records with, was a 0.271" neck, I run a 0.267 bushing. Don't fool with turning neck. I was 0.015" into the lands. I wanted enough grip for the bullet not to move. Start with a 0.267" and be sure you have a good chamfer on you necks with a VLD reamer. 33.5 gr is a stiff load of Varget, may be your primer problem. Get your speed at 2975 f/s, that is the best speed for the 105 and 108 Berger. any faster is not needed. The 6BRX can run 3100 + but I have had 5 - 6BRX barrels, they all shoot at 2975 f/s.

Mark Schronce

MarkS, Feb 22, 2016 Report

Setting records without turning necks or annealing? How can that be?

Yes that was many years ago and the aggregates are smaller now then the records were then. Matt

 

[rayjay]

IMO the only way to control neck tension and have it the same every shot is to anneal every firing. Otherwise it's different every reload as the brass work hardens.

 

[500Stroker]

IMO the only way to control neck tension and have it the same every shot is to anneal every firing. Otherwise it's different every reload as the brass work hardens.

IMO ? Please enlighten me.