Does neck tension increase over time?

[bfk4lyfe]

I chronoed some of my reloads I’ve had sitting for about 3 months and they were 10fps today faster today than they were when I chronoed them in the summer (it was 40° cooler today).

This is also 40fps faster than the last time I chronoed them in the temp it was today.

The SD went from a consistent sub 10, to 17 as well (for 10 shots).

A friend of mine said he read somewhere that neck tension can increase over time and to seat them long and reseat to proper length just before shooting.

Group size was the same and I don’t shoot over 1k or compete so I’m not concerned, just curious.

Barrel had about 400 rounds on it last time I chronoed it, so I would assume it was all sped up then.

 

[straightshooter1]

Basically, yes . . . "neck tension" can increase over time, on unloaded brass due to spring back. One can see this by measuring your brass right after you've sized them and again a day or two later.

However, on loaded cartridges, I wouldn't say "neck tension" increases much if at all, but due to the issues of "welding" over time there can be more interference/resistance between the bullet and neck wall.

Depending on one's chrono with its design, there can be some differences in measurement due to temperature changes and lighting that might add to the difference one is seeing.

 

[918v]

^^^
yes

 

[bfk4lyfe]

Ok makes sense. So if you had down time on a rainy day, would you bother to load ammo at all, or is it ok to load them way long and reseat prior shooting?

 

[stewarmy01]

“Neck tension” will increase with each subsequent reloading cycle due to work hardening if you do not anneal. It has been mentioned that about 3 reloads without annealling will net acceptable results to maintain similar neck tension, but I anneal every time. It seems like your issue is welding as mentioned above. Some people seat long and push the bullet to the correct depth just before shooting. I use Redding graphite case neck lube before seating bullets to combat this.

 

[918v]

If you use dry graphite in the necks you will not get neck weld.

 

[natdscott]

If you use dry graphite in the necks you will not get neck weld.

And DON’T CLEAN YOUR FIRED BRASS SHINEY LIKE A MIRROR.

Shiney brass is for the tailgate expo.

 

[seanh]

No, brass does not magically increase tension over time by just sitting there. Most likely, it's an atmospheric condition or recoil velocity related

 

[stewarmy01]

No, brass does not magically increase tension over time by just sitting there. Most likely, it's an atmospheric condition or recoil velocity related

Go load about ten rounds and pull one per month. I guarantee their will be increased resistance each subsequent pull. This isn’t because neck tension magically increases, but due to corrosion on a microscopic level due to contact of 2 different metallic alloys. Same reason they don’t advise you to mix aluminum and steel fittings for plumbing. This usually only occurs with folks that clean with SS pins, like me, hence my use of graphite. Folks that just corn cob or walnut tumble do not typically have this issue because the carbon acts as the buffer between the metals. I still experience some weld even with the use of my graphite because I clean the necks to much, so I graphite and seat long for the rounds that matter.

 

[natdscott]

It doesn’t weld much if you put a little lube in there with a q-tip before seating.

 

[918v]

It doesn’t weld much if you put a little lube in there with a q-tip before seating.

That only works if you’re chasing lands.

 

[stewarmy01]

It doesn’t weld much if you put a little lube in there with a q-tip before seating.

Agreed, but I am OCD and can’t stand for the kernels to stick inside the neck. Also, the graphite is inert and will not affect your powder. A lot of the paste, spray on, and wax lubes can ruin your powder, even if it is just a few kernels, it could affect your SD/ES.

 

[seanh]

Go load about ten rounds and pull one per month. I guarantee their will be increased resistance each subsequent pull. This isn’t because neck tension magically increases, but due to corrosion on a microscopic level due to contact of 2 different metallic alloys. Same reason they don’t advise you to mix aluminum and steel fittings for plumbing. This usually only occurs with folks that clean with SS pins, like me, hence my use of graphite. Folks that just corn cob or walnut tumble do not typically have this issue because the carbon acts as the buffer between the metals. I still experience some weld even with the use of my graphite because I clean the necks to much, so I graphite and seat long for the rounds that matter.

You absolutely do not know what you're talkin about

 

[stewarmy01]

You absolutely do not know what you're talkin about

Under what basis do you know genius?

 

[stewarmy01]

Dissimilar metals can react and switch electrons and eventually "weld" to one another. Galvanic corrosion, electrolyic corrosion, electrolysis are other terms for it. Leaving the carbon from firing in the case necks is a buffer to prevent it as is a dip in graphite lube or HbN etc. Anything to keep direct contact between the two metals will help prevent it.
https://forum.accurateshooter.com/proxy.php?image=https%3A%2F%2Fgalvanizeit.org%2Fuploads%2Fdefault%2Fgalvseries.jpg&hash=e3480d9cb20b372ef39088777ee10e53

 

[seanh]

So you claim that brass just sitting there increases neck tension, ammunition sitting on the shelf increases neck tension over time... sounds like you should go work for Joe Biden

 

[stewarmy01]

No, the neck tension does not increase, that is impossible. The bullet welds to the neck.

 

[918v]

So you claim that brass just sitting there increases neck tension, ammunition sitting on the shelf increases neck tension over time... sounds like you should go work for Joe Biden

factory ammo has a layer of wax in between the neck and the bullet so the two don’t weld.