Spring back

[Texas Solo]

How long does it take for brass to spring back as much as it's going to?

Every now and then, I get a round that's tight to chamber. Not many but it makes me wonder why. I've checked seating depth on suspect round, but it's always spot on. Same with neck size.

I'm going to try sizing 50 rds, wait a day, then size again. It might sound dumb, but I have the time so why not.

 

[D-4297]

Might be a case of Shoulder "Bump" length , or even Case Diameter at the "200" line . Think I'd check those areas also .

 

[Texas Solo]

Might be a case of Shoulder "Bump" length , or even Case Diameter at the "200" line . Think I'd check those areas also .

I'm thinking it might be the 200 line.
That's why I'm going to size twice

 

[Murray Brook]

Take one of the problem cases and fire it, then resize your normal way and take measurements. Wait 24 hrs and remeasure. Should tell you what is happening. JMO

 

[47WillysGuy]

How long does it take for brass to spring back as much as it's going to?

Lapua cases with 8 firings - no headspace spring back after 3 days .

Peterson cases with 1 firings - 0.0007”headspace increase after 3 days.

I do aneal for 8 seconds to red-orange colors, also.

 

[L.Sherm]

My thinking is if the .200 line is your problem then your die to reamer is a poor match to begin with.

 

[Dolomite]

what brass and sizing die are you using? how many firings on the brass?

 

[Doom]

How long does it take for brass to spring back as much as it's going to?

Every now and then, I get a round that's tight to chamber. Not many but it makes me wonder why. I've checked seating depth on suspect round, but it's always spot on. Same with neck size.

I'm going to try sizing 50 rds, wait a day, then size again. It might sound dumb, but I have the time so why not.

The answer to some extent depends on how much the case is resized and the hardness of the case. When you resize or bend the metal it has exceeded it yield strength and when the die is removed the metal doesn't return to its original shape.

I'm not a metallurgist but one way to reduce the time based component of springback is to increase the dwell time of the case in the die. As for how long I don't know the answer.

 

[M-61]

[QUOTE="Doom, post: 39269303,

but one way to reduce the time based component of springback is to increase the dwell time of the case in the die.
[/QUOTE]
Yes

 

[JFrank]

Every now and then, I get a round that's tight to chamber. Not many but it makes me wonder why. I've checked seating depth on suspect round, but it's always spot on

If it’s hard to chamber I would suspect the length isn’t getting set back enough, if you get bolt lift resistance I would suspect the .200 line isn’t getting reduced enough.
Just my 2 cents

 

[243winxb]

Spring back happens as soon as the case comes out of the die. (45acpTest, 5 different brands)

Just a few problem brass may be from the difference in annealing. The case body, near the head, can be stress relieved at around 480F.

Elastic Deformation/Springback: Cartridge brass, like many metals, exhibits elastic properties. When fired, it expands to seal the chamber and then "springs back" to its original shape for extraction. However, if the force exceeds the brass's elastic limit, it will undergo plastic deformation, resulting in a permanent change in shape. 76,000 PSI maximum.

 

[222Jim]

How long does it take for brass to spring back as much as it's going to?

Every now and then, I get a round that's tight to chamber. Not many but it makes me wonder why. I've checked seating depth on suspect round, but it's always spot on. Same with neck size.

I'm going to try sizing 50 rds, wait a day, then size again. It might sound dumb, but I have the time so why not

How long does it take for brass to spring back as much as it's going to?

Every now and then, I get a round that's tight to chamber. Not many but it makes me wonder why. I've checked seating depth on suspect round, but it's always spot on. Same with neck size.

I'm going to try sizing 50 rds, wait a day, then size again. It might sound dumb, but I have the time so why not.

I run into the same issue with my .22-250 Remington. I was neck sizing; works for my .222 Remington and .308 Winchester. I eventually figured out the problem with my higher pressure .22-250 was the case diameter immediately ahead of the case head was growing with each firing. Now I full length body size after every 3 firings and the problem has gone away.

Not sure if that's applicable to your cartridge/rifle combination, but it solved my "tight chamber" problem.

 

[Doom]

Spring back happens as soon as the case comes out of the die. (45acpTest, 5 different brands)

Just a few problem brass may be from the difference in annealing. The case body, near the head, can be stress relieved at around 480F.

"Elastic Deformation/Springback: Cartridge brass, like many metals, exhibits elastic properties. When fired, it expands to seal the chamber and then "springs back" to its original shape for extraction. However, if the force exceeds the brass's elastic limit, it will undergo plastic deformation, resulting in a permanent change in shape. 76,000 PSI maximum."

This description of what happens to the case is wrong. Most of the case upper body, shoulder and neck expand and exceeds the yield stress (elastic limit) but less than the ultimate stress on firing. Because it exceeded the yield stress and there is plastic deformation when the pressure is removed and the stress reduces the material will spring back but not to the original size.

Normally the case head and lower body do not exceed the yield stress.

Elastic Recovery (Springback) – EngineeringTechnology.org

engineeringtechnology.org

 

[243winxb]

From Olin Brass-
modulus of elasticity- Cartridge Brass-
Material is 70 copper/30 zinc with trace amounts of lead & iron , called C26000. Material starts to yield at 15,000 PSI when soft (annealed), and 63,000 PSI when hard.
Material yields, but continues to get stronger up to 47,000 PSI when soft, and 76,000 PSI when work hardened.
Modulus of Elasticity is 16,000,000 PSI. This means to pull a 1.000 inch long strip to 1.001 inch long induces a 16,000 PSI stress.
So if you pull a 1.000 inch strip to 1.005 inch long, you get about 76,000 PSI, which is the max obtainable.

 

[Webster]

How long does it take for brass to spring back as much as it's going to?

Every now and then, I get a round that's tight to chamber. Not many but it makes me wonder why. I've checked seating depth on suspect round, but it's always spot on. Same with neck size.

I'm going to try sizing 50 rds, wait a day, then size again. It might sound dumb, but I have the time so why not.

If you solve the problem be sure to let us know what it was. Simple measurements should find the oversize locations.

 

[Dave M.]

How long does it take for brass to spring back as much as it's going to?

Every now and then, I get a round that's tight to chamber. Not many but it makes me wonder why. I've checked seating depth on suspect round, but it's always spot on. Same with neck size.

I'm going to try sizing 50 rds, wait a day, then size again. It might sound dumb, but I have the time so why not.

Ever consider trim length???

 

[Texas Solo]

Ever consider trim length???

Cases are trimmed every loading.

 

[Straightshooter1]

How long does it take for brass to spring back as much as it's going to?

Every now and then, I get a round that's tight to chamber. Not many but it makes me wonder why. I've checked seating depth on suspect round, but it's always spot on. Same with neck size.

I'm going to try sizing 50 rds, wait a day, then size again. It might sound dumb, but I have the time so why not.

IMHO, 24 hrs is about what it takes. It could be less depending on the state of the brass and how much movement it went through for sizing.

It does help reduce spring back by giving plenty of dwell time when sizing. I find at least a minimum of 4-5 seconds of dwell time works best.

 

[searcher]

I think most spring-back occurs within the first 48 hours after sizing, starting out quickly the first few hours and slowly fading to almost nothing - though I have had situations where the spring back ended up being a tad more on brass sized after the first week (long explanation there...) I think there is no definitive answer here due to the characteristics being different between brands and lots - as well as how much annealed prior, etc. I once loaded up around 800 rounds of a particular varmint load, using 3X-fired Lake City .556 brass (all previously fired in the same gun) which had been annealed after the second firing. I shot that ammo on various hunts for the next month with no issues. I had used "just enough" neck tension to hold the bullets firmly and not slip during semi-auto use. All was great till I hadn't been on a shoot for several months. Pulled out that same batch of ammo and all the bullets were easily slipping into the necks - could just push them in with my finger. The necks definitely relaxed an additional .001" or more during that lay-up period - even though there was adequate tension for at least two months. That taught me a valuable lesson with my semi-autos. If I'm not going to soon shoot what I'm loading with certainty, I add another .001" or more to neck tension for the semi-auto if I didn't just anneal the necks. PITA pulling lots of bullets!

 

[JFrank]

How long does it take for brass to spring back as much as it's going to?

Every now and then, I get a round that's tight to chamber. Not many but it makes me wonder why. I've checked seating depth on suspect round, but it's always spot on. Same with neck size.

I'm going to try sizing 50 rds, wait a day, then size again. It might sound dumb, but I have the time so why not.

Helps to know exactly how much sizing my die is producing and just how much set back I’m using. I like to draw it out and put some numbers to each area for reference. I’m not against .003 set back in length and I really don’t experience much for spring back. Maybe I’m doing something wrong . IDK..