Does resized and belled brass shrink?

[henry-ctc]

Hi guys.

I was loading 200 (out of 2000 pcs of brass) 38 spl with 158 grs LSWC. The brass had been cleaned, resized and belled last year. It was stored in bags and have never seen extreme temperatures or any other unusual circumstance.

Well, after priming some of them I checked the belling. Not even a bullet could start the way inside the case without shaving some lead. I compared it to resized cases, not previously belled. I must admit that these were clearly below the diameter of the bullets. So, cases belled some months ago are now slightly narrower. As it´s a lead bullet I like a good bell, using a Lyman M die.

Eventually I rebelled all the 200 cases I was reloading and the outcome was perfect.

Has anyone experienced something like this?. Should I store my brass just resized, and belling only shortly before reloading it?. Does brass keep a "memory" of it´s previos size and wants to return to it´s old dimensions?

Thanks for the answers.

(Sorry, forgot to say that bullets are sized to .358 and brass is GFL)

 

[ranger335v]

"Does resized and belled brass shrink? "

Depends on the humidity.

 

[henry-ctc]

OK. I don´t think it´s a silly question, as what happened also surprised me. But if you want I can rename this thread.... How about "Stupid question...."?.

 

[243winxb]

There is a lot of talk about brass "spring back". I have never measured it, but feel it does happen. How much also depend on the hardness/softness of the brass.

 

[ApplePie]

I'm not a physicist, but I think it's entirely reasonable for a flared mouth on a brass case to shrink slightly back towards it's original size over time. There is elasticity in brass and other metals. Even though you have deformed the case mouth by expanding it beyond it's yield strength, some elasticity is sure to remain.

Good lesson! Don't bell the case mouth until ready to load a bullet into it.

The following quote is from
http://en.wikipedia.org/wiki/Plasticity_(physics)
"For many ductile metals, tensile loading applied to a sample will cause it to behave in an elastic manner. Each increment of load is accompanied by a proportional increment in extension, and when the load is removed, the piece returns exactly to its original size. However, once the load exceeds some threshold (the yield strength), the extension increases more rapidly than in the elastic region, and when the load is removed, some amount of the extension remains."

 

[doubleh]

I've never noticed it. I reloaded some 45 acp that was sized and expanded 2 years ago last week and it was still just fine. Not saying it's not possible but I've been reloading since the 70s and never encountered it.

 

[rcmodel]

No, actually it doesn't.

If it was belled properly a year ago, it would still be belled properly today, or five or 10 years from now.

I prep brass in large quantities, and store it in large quantities in .50 cal ammo cans or plastic frosting buckets with snap-on lids.

I am curently loading .38 Spl & .45 ACP brass I sized, expanded and belled probably 15-20 years ago..

If yours isn't belled properly today, it wasn't belled properly when you belled it a year ago.

rc

 

[Walkalong]

Agreed. Was it all trimmed to length, or was it different lengths?

 

[BYJO4]

I have never had a problem loading brass that had been previously sized and expanded. I think there must have been a problem when you originally expanded the cases.

 

[Striker Fired]

I had sized and belled a bunch of my spp federal brass and never got to loading all of them,(was testing and between weather and work took a month) they did indeed "shrink", or I should say spring back in a bit. I ran them back into the expander(still set-up) and they came back out to where they were origially. So they do(maybe some calibers more noticable) spring back in over time. I hadn't noticed this either till I started loading lead and was more intuned to lead shaving and how the bullets start in the case before going into the seater die(aka "M' die style step)

 

[gamestalker]

Any measurable amount of spring back is going to happen at the time the brass is belled. I can see how one might mistake the lack of enough bell for shrinkage, if you didn't load any of it until now though.

GS

 

[1SOW]

There is a lot of talk about brass "spring back".

I experience it in 9mm brass. It's not necessarily instant, but it seems to happen within a few seconds. I thought my caliper was bad. Same finding with a second caliper. Doesn't happen every time.

I sort and load by headstamp. WIN does it for sure. I guessed it might be relative to the "hardness" of the brass.

 

[Striker Fired]

I loaded several groups of 10 out of that batch the first time. They were indeed belled enough to begin with. They DID "spring" back a bit over the course of that month. AS I said the expander was STILL set-up from the first time .

 

[beatledog7]

As someone said above, there's every reason for not belling cases before you know what bullet will be used in them. Some bullets will seat fine with no flare; others will need a sizable flare. Why overwork brass needlessly?

 

[cfullgraf]

A quick search of the internet brought up a few abstracts of studies on the creep behavior of copper and copper alloys, of which brass is. So, I suspect that case mouths could "shrink" over time given the correct circumstances and conditions.

 

[Bovice]

For a given strain past the yield point, some materials exhibit "strain recovery" when the sample is unloaded from stress. This would mean that the brass "springs" back.

It isn't dependent on time, however. It occurs just as the brass case leaves the expander, and stays that way until you do something to it. The time delta from start to finish of strain recovery is very small.

 

[.22-5-40]

Henry..you didn't happen to use a homemade case-lube containing Preparation H did you?

 

[zeke]

Brass does spring back. If you belled your cases for a tight fit, you may find it harder to seat the bullets after awhile. If you leave some extra room, or set up belling die for shortest case length, you'll likely never notice it. And yes, not all brass cases have the exact same charcteristics.

 

[918v]

A quick search of the internet brought up a few abstracts of studies on the creep behavior of copper and copper alloys, of which brass is. So, I suspect that case mouths could "shrink" over time given the correct circumstances and conditions.

I agree.

I like to bell minimally, just enough for the base to clear the case mouth. I have seen the same thing. Now, if you bell a little larger, then when the brass springs back you'll still be able to seat them without issue. So bell a little more if you are going to store the brass.