Part 2 of 2: Testing Dilemma

[barefooter56]

merbeau,
If I am reading this right that your measurement across the mid-point of the neck on a loaded round is .276 and the measurement across a sized neck is .269. You are putting about .007 neck tension on that bullet. That's a lot. For a hunting round we usually recommend about .003-.005 neck tension. A few ways you can relieve the neck tension from a loaded round when you are using a standard full length or neck die is to have the neck sizing area of the die polished out .002-.003 by a gunsmith or the manufacturer. Get an expander ball for the next caliber up and polish it down to .002-.003 over bullet diameter . Or if its a Forster die they do now make expander balls for their dies that are larger than the normal bullet diameter used. Final fix is a bushing style full length die from Redding, Hornady, or RCBS and get a bushing ( Redding bushings will fit all 3 ) that is .002-.003 under the .276 measurement on a loaded round.
Hope this helps!
Take care,
Phil Hoham
Berger Bullet Tech

 

[merbeau]

Phil

Mid point measurement across the neck from the Lee Collet neck sizing die is 0.690 whereas the RCBS full length sizing die the measurement is 0.270 which is the same as the Nosler virgin brass. This is at the upper end of your provided range.

I called RCBS and they are sending me another expander ball unit (no charge) that will make the neck tension 0.003 after sizing.

Thanks for your help.

Robert

 

[barefooter56]

Phil

Mid point measurement across the neck from the Lee Collet neck sizing die is 0.690 whereas the RCBS full length sizing die the measurement is 0.270 which is the same as the Nosler virgin brass. This is at the upper end of your provided range.

I called RCBS and they are sending me another expander ball unit (no charge) that will make the neck tension 0.003 after sizing.

Thanks for your help.

Robert

Robert,
Good deal ! You are welcome!
Take care,
Phil Hoham
Berger Bullet Tech

 

[Mikecr]

For a hunting round we usually recommend about .003-.005 neck tension.

This is not really possible, nor prudent to recommend.
You must realize that bullet grip amounts to no more than springback of necks(which is 1 to 1.5thou max). Any sizing of necks more than 1.5thou of interference is just causing excess seating forces, and contributing nothing more as far as 'tension'. In that case, you're using a bullet as a neck expander, and bullets make terrible expanders.

Most credible sources recommend 2-3thou neck sizing from loaded diameter, and assuming no expansion to follow, 2thou downsizing springs back outward to leave ~1thou interference(tension). If planning to expand necks, which is beneficial where using a mandrel to do so, you could size down 3thou interference followed with expansion to again leave 1thou interference(but expanded interference -which is different).
This is about all the tension achievable anyway, as tension = springback.

 

[barefooter56]

This is not really possible, nor prudent to recommend.
You must realize that bullet grip amounts to no more than springback of necks(which is 1 to 1.5thou max). Any sizing of necks more than 1.5thou of interference is just causing excess seating forces, and contributing nothing more as far as 'tension'. In that case, you're using a bullet as a neck expander, and bullets make terrible expanders.

Most credible sources recommend 2-3thou neck sizing from loaded diameter, and assuming no expansion to follow, 2thou downsizing springs back outward to leave ~1thou interference(tension). If planning to expand necks, which is beneficial where using a mandrel to do so, you could size down 3thou interference followed with expansion to again leave 1thou interference(but expanded interference -which is different).
This is about all the tension achievable anyway, as tension = springback.

Mikecr,
The .003-.005 neck tension is including the spring back. So you would size the neck down .003 to get .002 , .004 to get .003 and so on. As the brass gets more use you do have to size the neck down farther in size than when new to get the same neck tension ( unless you anneal). We have found that the .003-.005 neck tension usually prevents the bullets in the magazine from setting out or setting back under recoil . For heavy recoiling magnums you may have to go to .004-.005 in some cases. Again, this is for hunting rounds not target where a lighter neck tension may be desirable and can be used because of single loading rounds. For bushing selection the general rule of thumb we have used is : Redding tube style bushings , get a bushing that is .001 to .003 under the measurement across the neck of a loaded round . Redding bushings in many cases , not all run a little tight so .001 under may give you .001 to .0015 neck tension including spring back, .002 under .0015 to .002 and .003 .0025 to .003. Always check! Wilson bushings usually are : .002 under the measurement across the neck of a loaded round is .001 neck tension , .003 is .002 , .004 is .003 and so on + / - .0005. Again , always check! Especially if the rifle you are loading for is a Hunting, semi-auto, pump or lever action ! Because of the ways these rifles operate or are used for (Hunting bolt action) you need to make sure the bullet has enough neck tension so it will not set out or set back under recoil or being cycled through the action in the feeding process to prevent pressure and accuracy issues. I hope this clarifies what I meant in the comment above.
Take care,
Phil Hoham
Berger Reloading Tech.

 

[Mike 338]

barefooter...

Recommended neck tension for something in the 338 win mag recoil range?

 

[merbeau]

In my RCBS 30-06 dies the neck on a full length sized case is 0.330 and the Nosler virgin brass is 0.330. After seating a Berger Hybrid 155 grain bullet the neck size in 0.332 for a neck tension of 0.002.

It was obvious after speaking with the RCBS representative yesterday the mandrel for my 243 was not correct and RCBS did not hesitate to send a replacement.

Phil made a statement to always check which is sound advice.

 

[barefooter56]

Mike 338,
If you are loading the magazine box you may want to start at .002 or .003 and make some dummy rounds and test as explained in my last post. IF its new brass this may be enough so the bullet doesn't set out or set back under recoil . Depends on the brass and the spring back. If its fired brass .003-.005 may be the place to start including the spring back . Again , it depends on the brass and the times its been fired. If you are using the rifle in the "single shot" mode .001 to .002 with spring back may be a good starting point if the brass is new. .002-.003 if its been fired a time or two. If you are seating the bullets to touch or into the lands the least amount of neck tension should be the way to go due to pressure considerations. Downside is that if you have to un-chamber a loaded round you may leave the bullet stuck in the lands. Bad news on the range . Beyond bad news out in the field. That's why we never recommend seating a bullet out to or into the lands on a hunting rifle. As you can see neck tension is subjective and its usually the last thing tested in load testing. All rifles are there own entity ! No two are alike . That's why using someone else's load or seating length etc. is never recommended. You have to find what YOUR rifle likes for what you will be using it for.
Take care,
Phil Hoham
Berger Bullet Tech

 

[Mike 338]

Much appreciated.