Neck tension .001 to .003 questions

[M113A3]

I recently bought some Redding dies to start reloading for a new rifle. I decided on buying a bushing according to the Redding website which suggested .001 smaller from a loaded round. I have not starting yet but recently read that .001 neck tension might not be enough if the bolt is run hard.

I was thinking that the bullet might move when it hits the feed ramp and then enter the lands off center... which I guess would induce run-out and lower accuracy?

I have also recently read the thickness of the brass is a factor in neck tension i.e. thicker can increase while thinner can reduce neck tension when sizing?

I am not sure if I am over thinking this or not so I decided to post the question.

Cheers

 

[mdmp5]

Redding went from recommending 2-3 thousandths to 1 thou back around 10 years ago, when most of reloading was done by bench rest guys. Today, it is more common for guys to be running more neck tension. I personally run between 1 and 2; I say between because there is some slight variance, and I am often between sizes. Never had any issues doing it this way. I think if you talk to most guys today, they are at least 2 thousandths, especially guys who shoot matches

 

[FatBoy]

I run .003-.004" NT on my Tempest. Still very accurate,(same as .0015" NT) I just need to make sure I have a good chamfer on the case mouth or it shaves jacket.

 

[M113A3]

Might have to buy a new bushing,,, I am going to recheck my measurements since I was using a cheap caliper but decided to spring for a Mitutoyo before I do.

Thanks guys.

 

[mdmp5]

Might have to buy a new bushing,,, I am going to recheck my measurements since I was using a cheap caliper but decided to spring for a Mitutoyo before I do.

Thanks guys.

I typically use a mic when checking neck tension because of the better resolution and repeatability with the ratchet. Just make sure you get multiple measurements with the calipers before you make your choice of size

 

[FatBoy]

Consider a K&M neck mandrel. It's an extra step, but it doesn't matter what the neck wall thickness is, as long as you size it smaller than the mandrel it will open the necks the same on every case. Once you figure out what Neck tension works you can order a custom mandrel size.

As to the bushing, I always get 3 or 4 for a caliber size. Eventually the necks will thin and you can drop a size.

 

[mdmp5]

Yes I agree with the above. I rarely get it right with one bushing. I think I had 8 or 9 for 308 and 300 win mag, but I did have different brass.

 

[Diver160651]

Neck Tension is not measured by the size. Harness from the brass or influences from work hardening or annealing make a HUGE difference.

The only thing we have to “measure” neck tension via seating resistance are arbor presses like 21st century or K&M

 

[mdmp5]

Neck Tension is not measured by the size. Harness from the brass or influences from work hardening or annealing make a HUGE difference.

The only thing we have to “measure” neck tension via seating resistance are arbor presses like 21st century or K&M

Do you have either of these pressure gauges? If so, how do you get the correct depth?

 

[Diver160651]

Do you have either of these pressure gauges? If so, how do you get the correct depth?

Yes, the depth is set with the die.

But lots of great ammo has been produced with any press.

Understanding the feel of what is happening during the seating process is the largest hurdle.

 

[mdmp5]

Does the die have mic settings?

 

[Diver160651]

Does the die have mic settings?

Yes.

But again, you can make very good ammo guessing then the NB and understanding if the NT “feels” to light or excessively hard to seat.

 

[GONE BAD]

After using an expander ball I then tried a Redding bushing die.
Now I use a Lee collet die for my 260 and its the best I've used. I haven't resized or anneiled in 4 firing and the rifle shoots .3s

 

[Diver160651]

After using an expander ball I then tried a Redding bushing die.
Now I use a Lee collet die for my 260 and its the best I've used. I haven't resized or anneiled in 4 firing and the rifle shoots .3s

Yes, a lot of great ammo can be made. But for the sake the neck tension question:

NT, or inconsistency of it, is it one of if not "the" largest contributor to higher than expected ES. At normal ranges, not a huge deal. At 100, if the ammo is straight and loaded well, even with a NT issue that produces maybe 30+ ES you can get tiny groups. You see this really start messing with everyone at ELR ranges and of course F-class and benchrest were the ranges are longer, the guns stable and the targets measured.

 

[M113A3]

I have read when developing a load for a specific barrel\rifle keeping the ES to the single digits and a larger group is better than at smaller group with double digit ES. I cant recall who wrote that but it was in conjunction with the 6.5 guys and load develop.