284 necks getting thicker?

[Drolds72]

Just finished sizing some fired brass. I had some left over rounds that were spot on 310 loaded necks. The fired brass was turned at the same time as the brass in the loaded, left over rounds. I seated a bullet into the just sized brass, and have found that what used to be 310, is now .3103-.3105. Measured the thickness before and after sizing, and it was the same. My question is, do the necks normally get that thick after a firing? How often do guys turn necks to keep the same clearance?

 

[Immike]

Stick a bullet into a fired case and see if it’s clear all the way. You may be seating into the neck shoulder junction too far. We usually try to only use about 3/4 or less of the neck to avoid a donut. Did you turn all the way to the junction also? You may need to do a cleanup now that you fired once.

 

[Drolds72]

Stick a bullet into a fired case and see if it’s clear all the way. You may be seating into the neck shoulder junction too far. We usually try to only use about 3/4 or less of the neck to avoid a donut. Did you turn all the way to the junction also? You may need to do a cleanup now that you fired once.

I turned down about .030 into the neck. Bullet does slip into a fired case. Will remeasure after I shoot these again, and see if they continue to thicken, or stabilize. This is my first barrel with a tighter neck. New concept to me

 

[Immike]

You’re alright as long as they release, keep the chamber neck clean and keep checking fired cases for clearance. Good luck bud. Don’t be afraid to ask more questions and the guys here will help you. I need to retire for the evening.

 

[Drolds72]

You’re alright as long as they release, keep the chamber neck clean and keep checking fired cases for clearance. Good luck bud. Don’t be afraid to ask more questions and the guys here will help you. I need to retire for the evening.

Thanks much! As I think about it, I should probably segregate the left overs from the stuff I am currently loading, due to potentially different neck tensions, right?

 

[Immike]

Thanks much! As I think about it, I should probably segregate the left overs from the stuff I am currently loading, due to potentially different neck tensions, right?

Absolutely, sorting and separating is your new way of doing things.

 

[243winxb]

Peening of case mouths when wet tumbling , with or without steel pins , may make necks thicker.

There have been a few threads saying its possible.

 

[ronemus]

How much neck clearance do you have? I've seen neck thicknesses increase, but not that much in one firing. The more you work the brass, the more it will flow in unexpected (and usually unwanted) directions.

 

[Drolds72]

How much neck clearance do you have? I've seen neck thicknesses increase, but not that much in one firing. The more you work the brass, the more it will flow in unexpected (and usually unwanted) directions.

It’s a 315 neck. Had .005 clearance, now just a few tenths less. Gonna shoot the old and new tonite and see if, the old ones get thicker, and see if there is a significant change in the poi.

 

[Stepsjframe]

Think about .265 to .267 should be a sweet spot.

 

[mikecr]

Necks do not get thicker on firing.
They get thicker with enough body shoulder sizing to cause a need for trimming. It's rolled into necks through squeezing order.
Donuts are an additional matter.

 

[Dusty Stevens]

Really?

If that were the case turning the necks once would be enough. So how come after 3 firing on my 260AI (converted Lapua Palma brass) I'm still removing brass? In about 10% of the case I'm still removing brass from 80% of the neck. Is this some kind of screw up on my part?

And what do you mean donuts are an additional matter? Are donuts totally unrelated to firing? Do they grow like mushrooms out of nowhere? Please educate me, I'm eager to learn.

Joe

Make a video just for him

 

[mikecr]

If that were the case turning the necks once would be enough.

It is enough, unless you're FL sizing.
I have cases, turned for a fitted chamber, with over 50 reloads on them. Neck thickness has not changed a bit.
I also have cases neck turned in in 223, 6br, and 6xc, that are sized but very little (partial neck, bumping only). The necks are fine as they were set initially.

When you fire necks, they expand and come out of the chamber thinner (not thicker). They're thickened back with down sizing. When I fire necks in a fitted chamber they do not expand to require any downsizing, and they stay right where they're at. Brass does not get thicker on firing alone.

Donuts are an additional matter in that they exist from the git go, little more difficult to truly remove, they form again on fire-forming(unless well mitigated), and build, with enough sizing to cause a need for trimming (not otherwise).
You can turn out donuts only to have a later reforming and it's not a 'problem' unless you make it so. That would be seating bullet bearing into them or FL sizing necks to bring them into tension.
Donuts are not normally 80% of necks. Maybe 10%.

 

[boiler_house7]

Mr Joe is spot on. I'm assuming this is lapua brass, norma is gonna flow even more. Anealling has a effect and The faster powders 4350 gonna make it flow more than 4831 in my experience as well. Just depends on how stiff your load is. I run the faster powders and I skim turn all my comp brass ever firing till around 4-5 firings then they seem to be headed the other direction from my experience.

 

[mikecr]

To me is seems like you're sweeping the dirt under the rug,

No, I've well explained to others here -why I don't have your problem.
That necks do not have to be re-turned over & over from merely firing them.

 

[243winxb]

Here is the thread on thicker necks from peening.http://forum.accurateshooter.com/threads/case-mouth-doughnut.3983036/page-2

I have measured necks getting thinner when using a standard FL die, with expander.
The factory 243 win brass i loaded, neck measured .276" and kept getting thinner for about the next 3 loadings. Then it stopped. Over working the brass was the cause. A fl bushing die would not do this, imo.

In general, brass flows forward, towards the case mouth. . This is why it needs trimming?

 

[Dusty Stevens]

Necks never seem to need re-turned until you run the cutter back over them.

 

[Drolds72]

So, I should be cleaning these up every so often, and verifying the headspace?