Reloading "Chamber formed brass" Reloading

[dmatzinger]

I have a general question hoping to get someone who knows the technical answer. I have been reloading for quite some time, so i feel i am pretty experienced, and my buddies come to me with questions. The specific question below, i am unsure of, and hoping someone can point me to an actual technical answer.

The question,
Why do we re-size and shape necked riffle brass? I have always done it, and when i reflect back, i dont know why, other than the book said too, and the dies pack comes with the die, so i do it by default.
I have a bolt action rifle that is "harder" to close on reloads.
this got me thinking, why? Obviously its the C.O.L, the brass or the chamber.

C.O.L is longer then spec, as i developed it for this chamber and rifle specifically, so initially i assumed that was it, so i load 1 round at the C.O.L dimension from the book, same issue.
Next attempt was the brass.
1. took fired brass with no projectile, and it loaded fine, (as expected).
2. Took a cleaned, dryed, re-sized piece of brass, loaded ok, (could feel the slightest drag as the bolt closed)...
3. added a projectile to that same brass, at the book dimension for C.O.L. and it was "harder" to close the bolt.

this pointed me to the re-sizing of the brass is slightly changing the neck, and creating this 'harder" loading reloads.
I am confident in my dies, they are dillion carbide, but this one chamber is slightly longer than "spec" and is why i am able to load long C.O.L.. but also creating an issue with the neck of the brass after re-sizing.

Long story but i think its important to my specific question, and why i want a technical answer.

I plan to reload 20 rounds without re-sizing the once fired brass. Basically using the chamber to form the brass by firing it once.

Thanks for your feedback.

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[kmk1012]

Does all the brass have the same resistance? I've had a couple brands of brass with slightly thicker necks that did the same thing. Some people trim the necks for uniform tension but not sure this is your issue.

 

[JRuby]

There are a lot more experienced reloaders than I. I have been reloading since 1982, so I have reladed a few rounds. The reason we resize the neck is to 1) provide a consistent neck in diameter 2) to ensure that there is proper tension to hold the bullet from round to round.
I have seen brand new brass that was not tight enough in the neck and would allow a bullet to move easily - one pass through the decapping / sizing die fixes this.

One other consideration about sizing is if the brass is designated to one specific firearm or may be used in others. I do not full length size brass, only neck size if it is to be used in one firearm. Full length sizing is primarily used to standardize a cartridge. One thing about neck sizing is that it assumes that your cartridge will always be in the same position it was fired in previoulsy meaning the cartridge lies in the chamber the same way with the previous top being the current top as it lays in the chamber otherwise you are changing the body dimensions once again.

 

[Koda]

Are you full length sizing or neck sizing only?

If your only neck sizing then after a few firings you have to full length size to start over.

Also, are you annealing before resizing?

 

[TTSX]

You tell me fired brass fits smoothly but "resized" brass is tight? Your die or your method must be off, brass doesn't get bigger when resized. You are trimming your brass, right? Right?

 

[dmatzinger]

Does all the brass have the same resistance? I've had a couple brands of brass with slightly thicker necks that did the same thing. Some people trim the necks for uniform tension but not sure this is your issue.

Yes in this Chaber it is all brass that i resize when i deprime.

 

[dmatzinger]

There are a lot more experienced reloaders than I. I have been reloading since 1982, so I have reladed a few rounds. The reason we resize the neck is to 1) provide a consistent neck in diameter 2) to ensure that there is proper tension to hold the bullet from round to round.
I have seen brand new brass that was not tight enough in the neck and would allow a bullet to move easily - one pass through the decapping / sizing die fixes this.

One other consideration about sizing is if the brass is designated to one specific firearm or may be used in others. I do not full length size brass, only neck size if it is to be used in one firearm. Full length sizing is primarily used to standardize a cartridge. One thing about neck sizing is that it assumes that your cartridge will always be in the same position it was fired in previoulsy meaning the cartridge lies in the chamber the same way with the previous top being the current top as it lays in the chamber otherwise you are changing the body dimensions once again.

This makes sense, and thank you. As my brass is dedicated per rifle, it looks like i need to buy a neck sizing die only.

 

[dmatzinger]

Are you full length sizing or neck sizing only?

If your only neck sizing then after a few firings you have to full length size to start over.

Also, are you annealing before resizing?

I am not annealing, but sounds like i need to start, i am using full length die only, but sounds like i need to get a neck sizer only.

 

[dmatzinger]

You tell me fired brass fits smoothly but "resized" brass is tight? Your die or your method must be off, brass doesn't get bigger when resized. You are trimming your brass, right? Right?

I actually case gauge each round, and it passes case gauge, maybe this chamber has an issue? and its not that is does not work, it is just "harder" or i can feel it on this rifle only when i close the bolt on reloads

 

[JRuby]

One consideration I am certain you have considered. When you stretch a cartridge you are taking that brass from somewhere - which is typically the base of the cartridge. Fortunately you can get away with this a bit. I resize 30-06 ammo for 338-06 and 35 whelen. Wildcatters have been doing this a long time. Brass is a bit forgiving but as you trim and remove the brass from the cartridge the case is weakening. In short be careful trimming your brass to much.

 

[Koda]

I am not annealing, but sounds like i need to start, i am using full length die only, but sounds like i need to get a neck sizer only.

If your full length sizing the brass should chamber easily or your not doing it right.
I dont recommend neck sizing.
Annealing before sizing will help.

 

[TTSX]

I actually case gauge each round, and it passes case gauge, maybe this chamber has an issue? and its not that is does not work, it is just "harder" or i can feel it on this rifle only when i close the bolt on reloads

Ok, great. Sounds like you're happy with your results. Or maybe there's a reason you're on the internet instead at your loading bench.

 

[HotLoad]

I bump the shoulder back 1 to 3 thousands on fire formed brass as to not run into headspace problems.

 

[whiskeybill]

Forty years ago I had a Ruger M77 (tang safety) in 22-250, heavy barrel varmint rifle, purchased new. Factory loads would chamber and shoot just fine. Once I reloaded that brass, it was difficult to chamber the loaded round. Upon firing, many times the case neck / mouth would crack. It didn't matter if I full length or neck sized. I thought it may have been the dies, so I bought another set. Same issue. And it didn't matter what brand of brass, but most of it was Remington or Winchester. I tried annealing, inside / outside neck turning, you name it. I had a Wilson case gauge, all the brass fit perfectly in that device. I finally got fed up with it and sold the rifle. The only guess I could come up with was it was a very tight chamber or out of spec in some fashion. I have never had another similar problem with any other rifle.

 

[po18guy]

Chamber a round then extract without firing. Are there slight rifling marks on the bullet? COL - even if in spec - might be too long for the chamber, due to a "fatter" ogive of that particular bullet. This may cause bullet-rifling contact even though it is at the same COL as other bullet designs or weights. Thus the difficulty chambering. Difficult extraction of fired rounds is another issue.

Bolt guns usually have the camming power to chamber tight rounds, whereas semis mostly do not. Some semis need a "small base" die to size the case to OEM spec or even slightly smaller, in order to chanber and extract reliably. Bench rest shooters use fire-formed cases and often seat the bullets with finger pressure, and many seat them out to where they just touch the rifling. This indexes both case and bullet as closely to bore centerline as practiable. Yet, each gun, case and bullet combo will shoot differently and testing is required.

 

[Mikej]

1. took fired brass with no projectile, and it loaded fine, (as expected).
2. Took a cleaned, dryed, re-sized piece of brass, loaded ok, (could feel the slightest drag as the bolt closed)...
3. added a projectile to that same brass, at the book dimension for C.O.L. and it was "harder" to close the bolt.

Sounds to me that your getting into the lands with the projectile.
If you can bring yourself to do it. (Poor/frugal man's method) Cut a case neck so the bullet will slide in the neck of the case, and then chamber it. Then measure the COAL on that test cartridge.

 

[dmatzinger]

I have to hornady tool for measuring,a nd i am .002 away from the lands

 

[Robear]

resizing reforms the brass back to correct SAAMI dimensions after it has been fired. When the cartridge is fired, the brass expands in all dimensions to the chamber size, forming a seal. When the pressure is diminished the brass shrinks slightly but not completely allowing extraction. The brass expands most at the neck where it is thinnest, and least at the web where it is thickest. Neck sizing sometimes allows the brass to continue to be used in the rifle where it was first used, but not always. Full length sizing reduces the brass to correct dimensions so it will fit in any rifle correctly chambered.

 

[JJ1911A1]

I would check how your full length sizing die is set up. If it is not set up properly it can actually make the shoulder length of the brass grow. As you size the neck the excess brass is pushed into the shoulder of the case. If the die is not set up properly and you are not bumping the shoulder back at all it could be adding as much as 3 thousandths to your overall head space on your fired brass. The way I check this is with a set of shoulder bump gauges and a caliper. It allows you to measure to a consistent spot on the shoulder of the brass to the base of the case. Measure a fired case from that rifle. Now you want to resize that case until that measurement is .002 to .003 thousandths less than the fire case. You do that by adjusting the die in very small increments. Then make up some dummy rounds and see how they chamber. Also check the overall length of your resized brass, if it too long it could be jamming the neck into the lands. As mentioned earlier if you are using a different bullet, make sure your OAL isn't jamming the bullet into the lands.

 

[Mikej]

I have to hornady tool for measuring,a nd i am .002 away from the lands

How does the tool know the profile of the bullet?