Necks Shrinking?

[Sixgun]

Has anyone ever had their necks shrink on their own? Five days ago I shot 100 rounds out of my new 6547. The same day I decap, SS tumble and dry. Before and after this initial process checking the necks, a bullet slides right in as does the mandrels (expander and turning). I checked them again last night....bullets and mandrels aren't going in!

The neck chamber on the gun is .293, the cases have not been sized yet and this is the first firing. They've been sitting in the loading block on my bench in approx 62-66 degrees. It appears the the necks shrunk on their own somehow. Even after annealing last night..still tight. Looks like I'll have to take the bushing out when I do size them.

 

[powderbrake]

I suspect the ss tumbling has peened over the edge of the necks. Try chamfering the inside edge, and try a bullet in it. Annealing may also make the neck go out of round (corrected when sizing) so a bullet will not enter.

 

[Sixgun]

Even before annealing

 

[mikecr]

The neck chamber on the gun is .293,

How do you know this? What do loaded and fired neck diameters measure?

 

[Milo 2.0]

I suspect the ss tumbling has peened over the edge of the necks. Try chamfering the inside edge, and try a bullet in it. Annealing may also make the neck go out of round (corrected when sizing) so a bullet will not enter.

This ^^^^

 

[Dusty Stevens]

^^^+1

 

[BoydAllen]

Try this sometime, with a set of cases that are all the same, same number of firings and sizings. Size some of them, and then wait a week and size the rest, keeping them separate, then finish the loading of both, taking note of any difference in seating force. This is best done with an arbor press and suitable seating die. If the tumbling is the culprit, trimming and rechamfering should do away with the upset case mouths and restore your slip fit...if that is it. In the past when I have expanded case necks and did not finish turning them all, a day or two later they would be too tight for turning and require, reexpanding. I do not tumble cases.

 

[Richard Coody]

Happens all the time. That is why so many competitive shooters either load the night before or at the range.

Size a bunch of cases and wait a week or so to charge and seat bullets and they don't shoot so good.

Annealing helps. brass springback over time really does happen.

 

[Texas10]

I've read over and over on this site and others that cartridge brass does not age after working or annealing, so stated in no uncertain terms by those with engineering degrees, metallurgists, etc.

Yet right here we have measurable results of brass shrinking with age, and I, for one, prefer to size just before loading and shooting.

The more I know, the more I realize I don't know...

 

[Milo 2.0]

My clothes shrink when I don't wear them for extended periods. I'm a guessing last yrs cargo shorts will be tight come May. My wife shrinks clothes of mine she does not approve of too.

 

[rardoin]

I've read over and over on this site and others that cartridge brass does not age HARDEN after working or annealing,

Fixed it for you....

 

[Sixgun]

How do you know this? What do loaded and fired neck diameters measure?

I asked the Smith. Not sure about loaded but fired is .2925

 

[Sixgun]

I did chamfer the edges and the expander mandrel slides right in but not a bullet. I dont see that the edge is rolled or anything? These are unsized cases. I checked almost 70 out of 100 and every one was the same.

 

[JimSC]

I always trim, chamfer and debur after each firing but I depin, FL resize, and clean the cases first. If metal "grew" after machining we would all be in a world of hurt, every piece of precision machined equipment in the world would come to a screeching halt. Brass will grow about .000009 for every degree F increase but it would require a temp increase of over 100 F get a change of .001 inche. People are convinced they have seen UFO's and bigfoot also, but I am skeptical.

 

[mikecr]

I asked the Smith. Not sure about loaded but fired is .2925

Could measure it. Do you think this doesn't matter to the concern?

 

[Sixgun]

Could measure it. Do you think this doesn't matter to the concern?

No it doesn't .I'm just trying to give as much info as possible. I'm just gonna size'em as normal and get them loaded.

 

[Brians356]

I do not tumble cases.

Hear, hear! I like the cut of your jib, sir.
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