trim&resize vs. resize&trim

[kingfamous]

So i messed up and trimmed about 500 5.56 LC cases that I thought were resized already. Turns out they were not. I trimmed them to 1.750. Now after resize they are 1.759, still just under the max 1.760. Just want to know if I did this right, or do you resize then trim? All the videos I have seen show them grabbing there brass and in a progressive press stage one would be resize, then prime, powder, then seat. So im thinking that they trimmed before resize. Just want to know if I need to resize all my brass before trimming them.

[Major Danger]

Resize, then trim. As you know, the brass is sized to a more long and narrow shape than it was right after being fired so you want to trim the brass when it is longest.

If you trim to the min length it may be possible to fire a number of times again before needing another trim, depending on the pressure of the load.

[bsumoba]

Short answer, you did not ruin your brass and you are okay so long as they are below max length for your chamber.

The general consensus is to trim after resizing because the brass typically grows after resizing in most chamberings. Some people may trim before because they think that the act of trimming changes the neck tension. Some people even trim a little more than the book stated trim length (this does not typically hurt the gun) so that they can get 2-3 more firings in their brass before having to trim.

Trimming is not entirely necessary so long as the brass overall length is shorter than the chamber's overall brass length. This spec for their chamber usually well known by guys who buy their own reamers. For most factory guns, they will be very close to 1.760" for a .223, which is the SAAMI spec for maximimum overall brass length.

It sounds like you are making bulk ammo or plinking ammo, so you are okay.

The reason to trim for most guys is so that you are not over this dimension because you could cause a number of failures in your gun: extraction, failure to feed, and possibly even some circumstances, a worse failure if you know what I mean.

For guys in the precision world: benchrest, extreme long range, f-class, etc. most of us will trim to a designated brass length after every firing to maintain consistency. Whether or not this truly effects your accuracy and precision varies from person to person and who you ask. If you ask me, I would tell you I do not know objectively because I have not tested it personally, but I trim anyways for consistency if anything.

[kingfamous]

yes, this is plinking ammo. So resize so case is at its longest, trim, then after firing clean then resize then check to see if they grew past the 1.760.
So am what Im seeing is that if people are resizing first then trimming they are running it through there resizer again for no reason on there progressive presses?

[kingfamous]

Should I chamfer and debur these 500 cases before I run them through the resizer just to trim and chamfer and debur again? Will it hurt the resizer to run a case that has all the burs still on it?

[Divernhunter]

Best to chamfer and debur before putting them into a resize die.

[bsumoba]

yes, this is plinking ammo. So resize so case is at its longest, trim, then after firing clean then resize then check to see if they grew past the 1.760.
So am what Im seeing is that if people are resizing first then trimming they are running it through there resizer again for no reason on there progressive presses?

chances are, they trimmed it on a separate step and they trimmed to minimum length or below minimum length to ensure that they will not be anywhere near max length. Then, they run it through a progressive. So, they most likely trimmed prior to resizing or they do not need to trim them because they are still well below max length.

Should I chamfer and debur these 500 cases before I run them through the resizer just to trim and chamfer and debur again? Will it hurt the resizer to run a case that has all the burs still on it?

YES IT WILL HURT...it will most likely damage and scratch your dies if you do not chamfer and deburr the brass prior to putting it in a resizer die. You might even cause galling and get them stuck.

If you trim and chamfer and deburr prior to resizing, I do not think you will need to chamfer and deburr after resizing. I might even be inclined to put them through a tumbler to ensure that there are no brass shavings left anywhere on the brass

[kingfamous]

so on the 500 that I trimmed before resizing. If I take one and measure it after I resize it its at max length. So your saying instead on chamfer and deburr all of these then resize then trim again and chamfer and deburr for a second time, I could just trim more off say to 1.745 then chamfer and deburr that way when I resize those it will grow to be below the max. That way it will save me a second chamfer and deburr step.

[CSACANNONEER]

They will not all "grow" the same when you FL size them. So, I suggest, resizing them and then either checking them or re trimming them. I would not consider it safe to just retrim them, size them and call it good without checking the OAL of EACH one prior to loading them.

[liber]

So im thinking that they trimmed before resize.

That's what I do, mainly because I only want to process the brass once. I tumble to clean, trim, and then run them through my progressive...(size/decap, charge, seat, crimp). I check the primer on all my rounds to make sure they look correct and wipe any excess lube off.

Some people like to decap before tumbling so the primer pockets get cleaned, but I am not as concerned about that as I am just keeping my dies clean, and cleaning the brass of course.

[kingfamous]

Liber,
what are you trimming your brass to before you resize? Obviously your not checking them after the resize if your using the progressive press.

[David-K]

After tumbling (cleaning and polishing with primer still installed) I re-size, de-cap, trim, chamfer, debur and finally clean primer pocket. It seems to me to make more sense to do your re-sizing before you trim. When it goes through the re-sizing die, the brass is being squeezed a little and like a water balloon, if you squeeze it in the middle it will grow on the ends. Why you would go to the trouble of trimming before you re-size, only to potentially need to trim again, seems like a waste of time.

[ar15barrels]

So am what Im seeing is that if people are resizing first then trimming they are running it through there resizer again for no reason on there progressive presses?

If you load on a progressive, you don't need the sizing die in the press if the cases were sized before they were trimmed.
When you need is to put a decapping die in the sizing die location.
The decapping die will remove the media from the flash hole.
Media gets in the flash hole when you were tumbling to remove the lube after sizing.

[liber]

Liber,
what are you trimming your brass to before you resize? Obviously your not checking them after the resize if your using the progressive press.

I'm using Giraud Tri-Way heads in my mill, they cost $90 for each caliber and I have one for 308 and one for 223.

No, I'm not checking them as I trim to .205" and the max allowable is .215". When I size, I only bump it about .001-.002, so there is no way the case can grow enough to exceed the max allowable, IMO.

[ar15barrels]

No, I'm not checking them

there is no way the case can grow enough to exceed the max allowable, IMO.

Why not actually measure them and KNOW instead of just giving an opinion?