Deburr question

[älg]

I wonder what people do re. deburring case necks.

If after trimming a lot of cases, some have been trrimmed and some - which had nox expanded over max. length- have not..... does deburring the not trimmed cases make sense?? It seems you are eating up material unnecessarily if you do it.

I do it any way but wonder what other reloaders opinions are.- deburr only if trimmed, or debur every time you reload??

 

[Matt_G]

If after trimming a lot of cases, some have been trrimmed and some - which had nox expanded over max. length- have not

I only deburr after trimming the cases.
The above quote implies you are trimming to the max length.
If that is indeed what you are doing, you should be trimming them to the min. length.

Another rule of thumb (assuming you are trimming the cases to minimum length) is to never trim cases a fifth time. When they need that fifth trimming, it's time to chuck them in the trash.

 

[KQguy]

Why do they need thrown away after the 5th trimming?

 

[Matt_G]

Actually, they should be thrown when they need the fifth trimming. So only trim them four times.
The reason is that when a case is fired and/or sized brass 'flows' forward into the neck.
This is why cases get longer with each firing and sizing cycle.
The prevailing thought is that when the case needs its fifth trimming, enough brass has moved forward from just ahead of the case head/web area to render the case weak in that area.
If you continue to use and trim that case, you will start getting head separations.
Most reloading manuals warn of this in their sections on case prep.

To quote Lyman 47th edition, page 54.
"Again, never trim a case more than four times. Brass cases are severely weakened with the flow of notable amounts of brass into the neck."

 

[KQguy]

Wouldn't that depend on how often you trimmed your cases?Would it be different for a guy who trimmed his cases down to minimum trim length,then didn't trim until they reached max length,compared to someone who trimmed after each shot to maintain a certain length,even if it was only .002" each time?I am not disagreeing with you,I just want to learn more about this subject.

 

[Matt_G]

The standard I gave is assuming the cases are trimmed to min length, after they have grown to max length.
In your scenario, yes absolutely, that standard wouldn't hold true.
I would look at it this way.
Assuming the difference between min and max case length is .010 inches, the cases should be thrown after .050 of an inch of brass has 'flowed' forward. In my scenario this would be when they needed that fifth trimming.
So in your example, if the cases are growing .002, and they are trimmed after every firing, they should be good for 25 reloads or 25 trimmings, assuming nothing else is wrong with the case.

HTH

 

[KQguy]

Thanks for clearing that up.:)
KQguy

 

[MagnumManiac]

I wonder what people do re. deburring case necks.

If after trimming a lot of cases, some have been trrimmed and some - which had nox expanded over max. length- have not..... does deburring the not trimmed cases make sense?? It seems you are eating up material unnecessarily if you do it.

I do it any way but wonder what other reloaders opinions are.- deburr only if trimmed, or debur every time you reload??

alg,
It is a normal practise to 'chamfer' case mouths when dealing with new brass, it helps bullets to seat without gouging jacket material off them as they're seated. I chamfer all new brass LIGHTLY, just enough to allow a small bevel inside and out.
You only need to do this once, until you need to trim them, and then you de-burr and chamfer your case mouths, you only want a slight bevel on the inside and outside of your case mouths, don't over do it and you will have cases that feed better and are easier to seat flat base bullets in.
Cheers.
MagnumManiac.
gun)

 

[Moman]

I trim to minimum every loading. I think this helps keep everything as consistent as possible. After trimming, I do what Magnum Maniac mentioned about lightly chamfer/deburring.

 

[älg]

MagManiac, I got the wrong word,. yes chamfer is what I meant.- I do give the case a slight chamfer with a Sinclair tool... the question was meant if a case has not been trimmed, do you chamfer or not?? I reckon you do not need to do it.

Thanks everyone for the replies.

 

[Michael Eichele]

Wouldn't that depend on how often you trimmed your cases?Would it be different for a guy who trimmed his cases down to minimum trim length,then didn't trim until they reached max length,compared to someone who trimmed after each shot to maintain a certain length,even if it was only .002" each time?I am not disagreeing with you,I just want to learn more about this subject.

To some degree you are correct. There is a difference between taking .002" off the neck and the neck only needing .002" off the neck. If a neck only needs a couple thousandths trimmed it can lost a while longer. If youre only taking a couple off and it needs more, its still growing faster than if it only needs .002"

It doesnt matter if you trim them or not. They still grow from firing and resizing, trimmed or not. It depends on how much they grow and how often is going to determine case life. Not if you trim them or not.

Not trimming is also dangerous because brass that is too long gets forced into the chamber and crimps down on the bullet casueing a huge pressure spike.

 

[Michael Eichele]

Actually, they should be thrown when they need the fifth trimming. So only trim them four times.
The reason is that when a case is fired and/or sized brass 'flows' forward into the neck.
This is why cases get longer with each firing and sizing cycle.
The prevailing thought is that when the case needs its fifth trimming, enough brass has moved forward from just ahead of the case head/web area to render the case weak in that area.
If you continue to use and trim that case, you will start getting head separations.
Most reloading manuals warn of this in their sections on case prep.

To quote Lyman 47th edition, page 54.
"Again, never trim a case more than four times. Brass cases are severely weakened with the flow of notable amounts of brass into the neck."

It will have more to do with how much the case needs triming than just trimming.

This method is assuming youre using a factory sloppy chamber. When brass is expanded alot and resized as in the case of a sloppy chamber, you will have to trim MUCH more than you would in a tight chamber. When you use a much tighter chamber and the brass isnt allowed to expand much and the resizing takes place, less brass moves forward. You can get many times more firings after 4 trimmings because youre only taking a very small amount off versus alot from a case fired in a sloppy chamber.

Neck sizing only nearly eliminates this problem but neck sizing only after a few firings leads to another set of problems.

 

[Michael Eichele]

Back to the original question.

What works best for me is I chamfer the necks on ALL new cases and then not again untill after any time I trim the necks.

 

[älg]

Thanks Michael.-