Resizing secondhand brass

[AussieShooter]

I am trying to achieve a uniform 308 case length of 2.005.

My brass is 2nd hand once fired lapua.

My questions are;

1. Can you use / should I use the body die included in the Redding Competion Neck Sizing Die set to resize the brass so the headspace is to the SAMMI spec then focus on the neck length or should I use a FL die and try to achieve the desired headspace and neck length to SAMMI spec in one go?

2. Is this reasonable given that I read you can not resize brass longitudinally?

Thanks.

 

[Sniper Uncle]

I may be crazy here, but I always understood that you size the brass to get the diameters right, shoulder bumped right for correct headspace, and then trim the case to get the neck length/case length correct. If the shoulder is at the SAMMI spec length, then when you trim the case to proper length, the neck length will be correct/consistent.

Did I totally miss your question?

 

[AussieShooter]

Hey Tim,

I wanted opinions on the best method of resizing brass to SAMMI spec but more importantly what I can / can not get away with.

What is the maximum headspace length before bumping back the shoulder would effect the integrity of the case?

Does bumping back the shoulder apply pressure between the head and the shoulder so the force is acting on the cylindrical section or does the bumping of the shoulder focus entirely on the shoulder so that any squeezing focuses the force on the shoulder and neck?

Is their a safety standard as to what the maximum allowable length can be before resizing so that the case mantains its integrity?

 

[AZ.noob]

Aussie,

I can't answer with a hard number, but provided that the brass was fired out of a SAMMI-spec chamber, I can't see why you can't resize it to your SAMMI-spec chamber, unless there's unknown factors here (custom/out-of-spec dimensions, etc). I've resized second-hand brass that was .009 out from where I needed it, and after annealing and resizing they're holding up just fine

 

[damoncali]

Use a gage to measure brass fired in your rifle. I'm partial to the RCBS precision mic. Then full length size your second hand bras to .002" less than that measurement. Then measure the overall case length. If it's less than 2.015, you're fine. If it's more, trim it back to 2.005". This assumes a SAAMI chamber.

 

[Sniper Uncle]

Most of us, myself included, either neck-size or just bump the shoulder back by .0015"-.002" for a bolt rifle. This is only to allow the bolt to close "easily." Any more will create unnecessary headspace and will weaken the brass leading to eventual head separation. As far as where exactly the force is applied when the shoulder is bumped, I haven't really given that any thought, nor have I read an answer to that.

Headspace refers to the "extra" room in the chamber not occupied by the casing. So, I'm not sure what you mean by "maximum headspace length before bumping the shoulder."
Typically, the way we set up a die is by taking a casing fired from our rifle, and working off that casing (or several), as they have been fire-formed to our chamber. Then, you set the dies to bump the shoulder on those casings by .0015-.002", and you have casings that will chamber fine and not have excessive headspace.
You will have to resize something a little every time, or you won't be able to get the new cartridges to chamber without a lot of trouble, and or you will not have any neck tension to hold the new bullet. Some people only neck size, some bump the shoulder too. I essentially neck size in a full-length size die---I only load for one rifle with those dies, so I set them to just resize enough to close the bolt without trouble, which hardly bumps the shoulder at all.
As far as maximum neck length, that is determined by the chamber of your rifle.
You want to be sure that you trim before you reach the end of the neck portion of the chamber, or you run the risk of crimping the projectile in when you close the bolt, causing very unsafe pressure potentials. You can get little inserts which go into a case that has been sized and had its neck shortened about .10" shorter than the published "trim-length", and has the primer pocket drilled out to allow you to push the insert back out. Then, you place the modified case with insert in it, into the chamber and close the bolt. The insert will bottom out on the end of the neck of the chamber, and be pushed back into the modified case, so when the bolt is opened, the case with insert can be measured to find the actual "maximum" case length for your rifle. You must trim when you approach this length, or you risk crimping the projectiles in the chamber and over pressuring your rifle.
Not sure if I answered your questions, but I hope this helps.

 

[damoncali]

Partial sizing with a full length sizing die is inadvisable. Details here:

The Rifleman's Journal: Basics: Resizing - Case Dimension Changes

 

[Sniper Uncle]

Partial sizing with a full length sizing die is inadvisable. Details here:

The Rifleman's Journal: Basics: Resizing - Case Dimension Changes

Appreciate the link here, but I question part of it, quoted here:
"A case that was reloaded to normal pressure level can exhibit many of the same symptoms of an over-pressure case if it was not properly resized. Just as the over-pressure case creates an interference fit in the chamber, the improperly resized case does not have enough room to expand as the pressure builds and will cause the chamber itself to spring outward slightly, then trap the case as it comes back to normal. The cartridge case needs room to expand in order to then spring back enough to extract normally."

What is the backing source for this? Reason I ask, is that this paragraph, if accurate, indicates that the brass casing, as weak as brass is in comparison to the steel chamber, is actually stronger than the steel casing----"the improperly resized case does not have enough room to expand as the pressure builds and will cause the chamber itself to spring outward slightly"---

Actually, I believe what happens is that the case which is very close to the size of the steel chamber is prevented from expanding enough to cause it to change size appreciably, so it won't stick too much. If the steel chamber expands enough to do this, then anyone who neck sizes only----many benchrest shooters--- should be having problems with their brass like this article says.

Secondly, the author seems to have a fundamental failure to under stand the principle of Partial Full Length Sizing.

Essentially, you are doing a Proper Full Length Size with the dies set to be as close to your specific rifle as possible. To do this, you disassemble your rifle bolt, and take a previously fired casing and place it in the chamber. Then you close the disassembled bolt. Stop when the bolt shows signs of resistance, and screw the die body down a tiny bit in the press, resize the case, and try it in the chamber again. You repeat until you can just close the bolt without it sticking. Then resize several more cases and try them in the chamber also.

In this manner, you will actually be doing a full length size, but to the smallest change in the brass that will still fit in the chamber.

The author of this paper adjusted his die arbitrarily, and created the problems he warns against. There is a proper way to do things, and there are other ways. I now question a lot of what he says in his article, as he did not properly set up his dies for his article, calling into question his expertise in writing the article. I do not question that what he says will happen by doing the procedure he outlined may actually happen. I just state that in my opinion he missed the point of partial full length sizing, and condemns it because he set it up wrong, and it did bad things.

 

[damoncali]

I don't think you are incorrect. I'm not sure what he's getting at with the chamber expansion bit as it doesn't make sense to me. I woud think that a close fit is fine for the reasons you state. My bench rest rig is set up that way and it works perfectly. The way I see it you need the case to deform plastically into an expanded chamber for it to stick as the chamber springs back around a now larger case. That's pressure, not sizing. But honestly, I don't understand it fully, because you'd never have to resize if that were all there is to it.

I mainly wanted to point out that adjusting full length dies to do a partial sizing is misguided, and he shows some data to describe why. What you are describing is the proper adjustment for full length sizing, which is of course, the goal. I believe I misinterpreted your earlier statement that you were just "neck sizing" with a full length die, and wanted to make sure the novices out there didn't get the wrong message.

 

[Sniper Uncle]

I don't think you are incorrect. I'm not sure what he's getting at with the chamber expansion bit as it doesn't make sense to me. I woud think that a close fit is fine for the reasons you state. My bench rest rig is set up that way and it works perfectly. The way I see it you need the case to deform plastically into an expanded chamber for it to stick as the chamber springs back around a now larger case. That's pressure, not sizing. But honestly, I don't understand it fully, because you'd never have to resize if that were all there is to it.

I mainly wanted to point out that adjusting full length dies to do a partial sizing is misguided, and he shows some data to describe why. What you are describing is the proper adjustment for full length sizing, which is of course, the goal. I believe I misinterpreted your earlier statement that you were just "neck sizing" with a full length die, and wanted to make sure the novices out there didn't get the wrong message.

Point well taken, and actually, as I thought about it, I was somewhat miss-leading in my original post in saying "partial" full length sizing. I said that to differentiate between setting the die by the manufacturer's instruction which would probably be to SAAMI spec, versus adjusted to closely fit the gun, and in a sense only partially sizing it, as it would not be down fully to SAAMI spec.
Appreciate you pointing it out, as I don't want to miss-lead any readers who might not understand what I was trying to say, and might do what that author talked about doing.
Thanks for the correction.

 

[roggom]

Lot of info in this thread.

I have some virgin Lapua brass and did some measurements. The avg oal was 2.005 and the avg HS was .003 under Saami (using an RCBS precision mic) Considering both numbers are under SAAMI, I would size 5 or 10 cases to the same spec as virgin brass, shoot them then work on a precise shoulder bump. Depending on your rifle, you dont need to keep sizing the necks down to 2.005 as the spec is 2.015. If you are shooting a Remmy your chambers throat is prob longer than that.

 

[buffybuster]

I didn't read everything here, so if someone already covered this, please excuse me.

My recommendation regarding secondhand brass, as you don't know the exact history, is to Full Length resize down to minimum spec. If you resize only enough to your headspace, you might still have trouble chambering and extracting, if that brass was fired in a chamber that had a larger base diameter. You can check by resizing to your headspace and see if the case will chamber smoothly. If not, you need to resize further down. Once you do it that first time, then it should be GTG from then on out, though the brass might not last as long, as least you know it will chamber. Beats sticking a unfired round in the chamber.

 

[BobinNC]

...Essentially, you are doing a Proper Full Length Size with the dies set to be as close to your specific rifle as possible. To do this, you disassemble your rifle bolt, and take a previously fired casing and place it in the chamber. Then you close the disassembled bolt. Stop when the bolt shows signs of resistance, and screw the die body down a tiny bit in the press, resize the case, and try it in the chamber again. You repeat until you can just close the bolt without it sticking. Then resize several more cases and try them in the chamber also.....

I pulled out part of your quote to illustrate several important points:

First, you are correct, the best and most useful case gage in a reloaders arsenal is the rifle with the brass it is to be fired in. So if you get once fired brass, not fired in your rifle, the first thing you should do it see it it fits!!! Most likely it won't, but then using just a single piece of brass FL resize it incrementally until it does just fit smoothly. Size a few more and try them in your chamber. That's minimum sizing at it's best using your die and your rifle.

The part I don't get is disassembling your bolt??? It's a fired case, no primer, no powder, it's not going to go off. No need to disassemble your bolt...

This technique only applies to bolt action rifles, for autoloaders like AR-15's you need to FL size and then some, often using a small base die.

 

[Sniper Uncle]

The reason to disassemble the bolt is do that you have no resistance from the ejector pin. This gives te truest reading of chamber size. Otherwise, you might give yourself a tiny bit extra headspace. The goal here is to achieve as close to perfect fit as possible leaving just enough room to extract easily and successfully. I have done it both ways and honestly can't see the difference, but I was corrected by a man who has loaded many more than I, so I defer to him on this.

 

[db_17_85]

Uncle,

As to the expansion of chamber/brass, here's my thoughts...

The chamber itself should expand regardless of brass sizing. Not much mind you, but a bit. As for the brass, let's call the starting point (standard FL sized) X. When the chamber is at maximum pressure, the brass will grow to say X+10. Once pressure subsides, it will shrink to X+5. That's the "springyness". If the brass is inserted at X+5, fired to X+10, it may only spring back to X+7. As this cycle goes on, the brass will no longer spring back from the chamber walls enough to have reliable extraction.

Like I said, my thoughts on the subject and worth what you paid.

Sorry for the off-topic OP. As to your situation, I would prep the brass is if it were brand new. FL size, trim to your chamber length, etc.

 

[insight3b]

Brass fired through another rifle needs FL sized the 1st time its fired through a different rifle

 

[Sniper Uncle]

Uncle,

As to the expansion of chamber/brass, here's my thoughts...

The chamber itself should expand regardless of brass sizing. Not much mind you, but a bit. As for the brass, let's call the starting point (standard FL sized) X. When the chamber is at maximum pressure, the brass will grow to say X+10. Once pressure subsides, it will shrink to X+5. That's the "springyness". If the brass is inserted at X+5, fired to X+10, it may only spring back to X+7. As this cycle goes on, the brass will no longer spring back from the chamber walls enough to have reliable extraction.

Like I said, my thoughts on the subject and worth what you paid.

Sorry for the off-topic OP. As to your situation, I would prep the brass is if it were brand new. FL size, trim to your chamber length, etc.

The expansion of the brass is predicated on how much the chamber will allow that expansion. Brass would expand as far as it could, until it is stopped by some means, as in the chamber. There is no evidence that brass will always expand by a certain factor. If there were, then there would be no worry about excessive headspace or any other such expansion, because it would only expand by the same factor. This does not happen, and headspace is an issue, in my mind proving that the brass expands as much as is allowed, and no more. Otherwise, the brass would always stick in the chamber when neck sized.
I would agree that the brass needs to be sized according to the new rifle chamber, as a couple people have mentioned above.

Brass fired through another rifle needs FL sized the 1st time its fired through a different rifle

Yes, it does need to be sized for this rifle, with the dies adjusted as described above.

 

[db_17_85]

Uncle,

I agree about the brass only growing to what the chamber allows. As for the constant expansion, I think you misunderstood me. What I am saying is that eventually (how many firings? I don't know) the brass will be the same size as the chamber before ignition and will no longer spring back from the chamber wall. It may still be extractable depending upon a number of things (cleanliness of chamber, cartridge angles, etc) but the overall RELIABILITY of extraction could suffer. For a benchrest competition rifle, that may not be an issue. They are religious with cleaning their bore/chamber and even the slightest increase in accuracy and brass life may be worth the risk. Personally, I want reliable accuracy. Each person has their own goals and acceptable standards and risks. It's up to the individual shooter/reloader to determine where they want to fall on the scale.

 

[Sniper Uncle]

Uncle,

I agree about the brass only growing to what the chamber allows. As for the constant expansion, I think you misunderstood me. What I am saying is that eventually (how many firings? I don't know) the brass will be the same size as the chamber before ignition and will no longer spring back from the chamber wall. It may still be extractable depending upon a number of things (cleanliness of chamber, cartridge angles, etc) but the overall RELIABILITY of extraction could suffer. For a benchrest competition rifle, that may not be an issue. They are religious with cleaning their bore/chamber and even the slightest increase in accuracy and brass life may be worth the risk. Personally, I want reliable accuracy. Each person has their own goals and acceptable standards and risks. It's up to the individual shooter/reloader to determine where they want to fall on the scale.

Please do not think I am being argumentative here. I do understand what you are saying.
However, the Brass expands and contracts differently than the steel chamber. It springs more. It will only expand as much as it is allowed to, and then spring back a portion of that. If it gets to where it cannot expand appreciably, then it will return to the same place it was. It will not get tighter and tighter until it is the exact same as the steel chamber. Think of a spring. If you bend it a certain amount, it always returns to normal. You have to take it past a certain point before it will not return fully. The only way for this not to happen is with very fatigued material. I suspect that you will discard brass for other reasons before you get to that point in a chamber.

While you may be correct in theory, I doubt you would ever see that happen in practice. But then, I have been wrong before many times, an could be wrong here too. I won't be able to test this theory, as I FL size with a carefully adjusted die, to minimize working as much as possible, but they are sized none the less.