Neck Tension/Seating Pressure Question

[Bart B.]

Regarding consistency, check post #56 in:

http://forum.accurateshooter.com/threads/bullet-sorting-methods.3945936/page-3#post-37165176

 

[fguffey]

Brass has a memory.

And I said I shot a few cases when testing receivers that were advertised as being suspect. I said when I finished the cases had no memory of what they were before I pulled the trigger and no one had a clue.

F. Guffey

 

[fguffey]

Yesterday however, when I went to seat the bullets the pressure just slowly increased constantly until the seater bottomed out. Since I was testing a new bullet, and thinking that may be the cause, I loaded some of the bullets I normally shoot with the same result. Then I thought, the only change in my routine, and it wasn't really a change, just a timing thing, was that the cases that I went to load had been annealed, sized and cleaned at least two months prior, in fact they were still sitting in the tumbler.

And I have noticed when a reloader is talking about tension the gages are marked off in pounds. I have tension gages, all of my tension gages are marked off in pounds. I noticed your gage is fluid dampened, I have gages that are fluid filled, I always like to install them after the dampening chambers.

F. Guffey

 

[fguffey]

I would like to have tension this and tension that, I know, it has to sound cool but bullet hold can be measured in pounds no matter what directions the bullet is going. I can measure the effort to seat a bullet, I can measure the effort necessary pull a bullet in pounds. I can not get a grip on seating with tensions because I do not have a conversion for tensions to pounds.

I do have a tension gage that measure deflection in thousandths.

F. Guffey

 

[BoydAllen]

I have observed the change in bullet seating force that comes with time after sizing. I believe that it is not a problem as long as your load was tuned the same way, with either newly sized or previously sized cases. My totally unsubstantiated theory on this is that when brass is sized grain boundaries are disturbed and weakened, and that over time they may return to their former condition. This is just an unproven theory, so don't get excited If someone tunes up a load with freshly sized cases and then uses the same load with cases that sat around for a couple of weeks after sizing before the loads were completed, then IMO there would be a difference in a significant variable that would be expected to affect tune. We need to be careful to test apples to apples. Tune both ways and compare the results, rather than use the same load with two different neck conditions. Generally, I do not size until I am about to shoot the loaded ammo. I do not shoot long range. All of this comes from years of experience loading at the range for short range benchrest.

 

[Bart B.]

I've charged then seated bullets the morning of a match and several weeks ahead. No difference in accuracy across three positions shooting them. Others have done and observed likely

There are some in benchrest disciplines that resize then prime, charge and seat bullets in cases minutes before a match.

It's a lot easier to resolve a 1/10th MOA difference in disciplines with no human and minimum environment variables effecting where the barrel points as bullets leave and how their trajectories change going downrange.
.

 

[Olde Man]

I have used an inside K&M neck mandrel without lube to size the neck right before loading the bullet. The thing that I struggle with is the variations that the mandrel creates in the carbon build up in the neck. I have used a bronze brush before the mandrel to uniform the amount of carbon in the neck and after to redistribute the remaining carbon to cover the bare brass marks in the neck. It seems to work them as soon as I think that I have found the holy grail it bites me with a way out pressure reading. I anneal every time, bump .0005 and size with a .003 under bushing, wipe soot and lube off outside then use .0015 mandrel. I think the problem comes from the varying amount of carbon inside the neck from shot to shot.

 

[Dave Way]

I have used an inside K&M neck mandrel without lube to size the neck right before loading the bullet. The thing that I struggle with is the variations that the mandrel creates in the carbon build up in the neck. I have used a bronze brush before the mandrel to uniform the amount of carbon in the neck and after to redistribute the remaining carbon to cover the bare brass marks in the neck. It seems to work them as soon as I think that I have found the holy grail it bites me with a way out pressure reading. I anneal every time, bump .0005 and size with a .003 under bushing, wipe soot and lube off outside then use .0015 mandrel. I think the problem comes from the varying amount of carbon inside the neck from shot to shot.

And that is exactly why I plan on testing with one new set of brass in my WSM this summer. I will completely remove all traces of carbon inside the necks after every firing and see how that affects consistency and accuracy. I know many say carbon in the necks acts as a lubricant however after the first shot, there is no way that I have come up with to control the amount of build up and keep it uniform from case to case. I do get single digit SD's already but what I really care about is small groups at 1K so it's going to get tested.

 

[dmoran]

It's a lot easier to resolve a 1/10th MOA difference in disciplines with no human and minimum environment variables effecting where the barrel points as bullets leave and how their trajectories change going downrange.
.

While I do agree.... but it also takes a lot more refined and detailed ammo and reloading practices to achieve the higher accuracy demands that are needed in order to do well and with consistency, in those disciplines. That so often are not demanded, performed, are over-looked, and taken for granted in other disciplines. A good reason for one to not speak much to disciplines that they have no first hand experience with, or not up to speed of the extents current times have evolved to.
Donovan

 

[Bart B.]

A good reason for one to not speak much to disciplines that they have no first hand experience with, or not up to speed of the extents current times have evolved to.

Likewise.

There are no forum rules restricting ones comments on any discipline or time frame other than what they have participated in.

Nothing has changed over the years except tolerances. They're different now. For people, ammunition and firearms.

 

[BOB LEE SWAGGER]

Not sure it's pertinent to your regimen, but I size soon after annealing and use a bushing .003" under. When I get around to loading, I use an extra step by opening the neck up with a .002" under caliber mandrel, just prior to charging case. Seating has been smooth and consistent, plus SDs are mid single digits. Just a thought.

.003" under loaded round and then .002" under caliber meaning for 6mm - if .271 then .268 bushing and .241 mandrel yielding .001 tension?

 

[farmerjohn]

Why did he quit at the number 56? Did something happen with number 57? Just wondering...

 

[Ccrider]

Thanks for the replies guys. It's always good to hear other's thoughts on a process that can be as variable as precision reloading. I had never entertained the expander mandrel idea but may test that. I know I will be testing to see if I can make any sort of correlation between the length of time between the initial annealing/sizing operation and then re-loading versus the SD's and or group size. If I come up with anything I will post it here. Dave.

You will be surprised at what the expander will tell you. Some pieces of brass harden faster than others. You know immediately if a case is different. It may not matter as much if you anneal after every shot.