Baffled, does Brass ever Shrink in size?

[Navybowhunter]

Hey all,

Noob question here. Awhile back a friend of mine, while teaching me to reload "necked" cases, walked me thru loading some 30-06 junk loads, to "fire form" the brass to my T/C Encore. Just getting around to reloading them.

I have done quite a bit .308 reloading since, so am getting more proficient. Figured I'd get the 30-06 hunting loads going.

The brass is Nosler Custom 30-06 brass. I know we trimmed and sized, and loaded 25 out of the box of 50. I separated the once fired from the "never fired", this evening I was setting up the trimmer to trim the cases that were fired.
I checked the books, and max case length is 2.494, Trim to length is 2.484.

I put the caliper on the first case (as I wanted to set up a master case, for future reference), and it measured in at 2.479, figured it was a fluke, next case same measurement. In fact all of the cases are below the trim length, right around 2.474-2.479.

Am I reading something wrong?

I also resized one, just to check, and I received the same measurement before sizing and after.

Help please.....Would you reload and shoot these?

R/

Chris

 

[armorpl8chikn]

Absolutely. The more you reload them the faster they shrink. I have a bunch of 223 that used to be 30-06. I am hoping to reload them until they turn into 5.7x28.

Just making a joke and pulling your chain dude. Nothing unusual about your brass. They are fine. They will not stay below trim length and there is nothing wrong with them being shorter than trim length. Just make sure you even them up to make sure they are all a fairly uniform length even if they are a bit short they will be fine. Don't worry they will grow.

 

[damoncali]

They're fine to shoot. A neck a few thousandths' too short is fine. A few thousandths too long can be a problem. Usually brass grows. I don't see why it would be impossible for it to shrink, though - especially if it's on the first firing where the brass has to adjust to the chamber. The other possibility is that you trimmed it too much the first time without realizing it.

 

[M40_A1]

Baffled, does Brass ever Shrink in size?

YES!!! And I'm baffled too!

I have some .45 Colt (straight wall, rimmed cartridge, mind you) that I use with black powder. As those shells are dedicated for black powder loads, they never get sized. The base of the bullet sits tight against the powder, and the crimp is supposed to hold the bullet in. But, the shells have gotten shorter and shorter to the point that I can no longer adjust the die down any more to get a crimp sufficient to hold the bullets in. When shooting now, the bullets are beginning to back out and bind the cylinder. Too often, I have to push them back in to cycle the action. I think I'm going to send the die to RCBS and see if they will grind the base of it so I can get a better crimp. Those shells are now well below minimum trim length. Is the BP combustion residue eating the zinc in the brass alloy, thereby causing it to get shorter? Search me! But, yes, it CAN happen, it seems.

 

[Navybowhunter]

Thanks all! I will trim em all to the lowest in the batch, and CHOOT EM! LOL

Love this site, no BS straight up good advice!

 

[Short Round]

Think of the chamber or your gun in profile, obviously it's wider than factory brass that has to fit inside any chamber. Upon firing you blasted your brass to match the larger chamber dimension. Think of the new brass as a road of 10 mile road length, upon firing you now took a longer route to get from the cartridge base to the mouth but only have 10 miles of road so you now come up short of your destination because you took the long way to get there. OK, it's simplistic and ignores case stretching but you get the idea.

When you FL size them you'll push the brass road back toward the shorter "distance" profile path and your brass will appear to grow again in OAL.

 

[old_heli_logger]

Yup, Short Round has it right. Most brass will shorten on the first firing. The brass that flows to fill your chamber has to come from somewhere.
BTW, your brass should start growing in length with subsequent firings.
Good luck!

 

[EMorr]

Everything that has been said to this point is correct, however I have to ask. Are you sure you trimmed the brass the first time you loaded it? I use Nosler brass exclusively in my '06 and every piece of virgin brass has been around 2.479" long right out of the box and never needed to be trimmed until they had at least 3 or more firings on them. I know not every box of brass will be the same but I have been through a few boxes and never needed to trim on initial prep.