Does brass 'relax'?

[AI Perfector]

Do we have anyone out there who can advise whether brass relaxes with time?

If two lots of identical brass are sized and loaded, say, 1/ a day and 2/ 6 months before being fired, could the neck tension vary due to relaxation of the brass?

[John MH]

Never heard of it and from what I know it won't relax otherwise lots of bullets would be falling out of cases.

[Jagged 77]

The brass is not going to alter its physical properties or external dimensions without something acting upon it (force, heat etc). If its just sat there then most likely any change as regards downrange performance over a period of time is likely to be caused by other factors.

[GarethM]

This thread might be of interest:

http://forum.accurateshooter.com/index.php?topic=3792938.0

 

4 pages of debate on the subject (and links back to old topics)

Gareth

[c18rch]

Haven't read the link but my opinion is that the neck tension difference is to do with any residual lube/powder residue left in the neck from sizing/previous firings. As above brass will not change unless acted upon.

 

Lube however can dry out/harden, depending on what is used and how much is in there.

[The Gun Pimp]

With our 6PPC cut necks - which are thinner - the brass will certainly 'relax' and not display the same neck-tension as freshly loaded rounds.

[AI Perfector]

Some interesting thoughts here, particularly in the article, (which I've yet to finish!!)

It seems to me that the question needs addressing by a metallurgist, who would probably take much of the guesswork out of it. Does anyone know a metallurgist, who would be prepared to offer a view - just on brass relaxation and nothing else - we al know that there are other variables upon which we could not expect him/her to comment?

[gbal]

With our 6PPC cut necks - which are thinner - the brass will certainly 'relax' and not display the same neck-tension as freshly loaded rounds.

Vince,is there any evidence that such 'relaxation' has any measure able effect on performance.As 6PPC tends to have fairly light bullet retention anyhow,it's perhaps a good extreme test case (other loaded rounds might suffer less).Unless there are problems-unfired bullets left stuck in the lands is a pain-then we don't need to worry too much about this one-and of course,if there are issues,there is a cure-shoot 'em sooner! (if the time span for any relaxation is known).

Cold shrinkage might of course negate any very small relaxation effects-so Diggle might sometimes cancel them out!

Gbal

[The Gun Pimp]

Most 6PPC benchresters will seat into the rifling - sometimes 'hard' into the rifling. This is where brass 'relaxation' could show up. Relaxed brass may allow the bullet to push back more rather than hard into the rifling. The difference would be small and barely measurable - but a benchrest shooter would avoid doing it - i.e. mixing rounds.

[gbal]

Most 6PPC benchresters will seat into the rifling - sometimes 'hard' into the rifling. This is where brass 'relaxation' could show up. Relaxed brass may allow the bullet to push back more rather than hard into the rifling. The difference would be small and barely measurable - but a benchrest shooter would avoid doing it - i.e. mixing rounds.

Thanks ,Vince-about what I reckoned.If it's 'barely measurable' even by bench rest standards,and would in most cases(I mean shooting sessions and within batches of ammo) be consistent-another desirable-essentially,not something most need to get too worried about.

Gbal