Novice reloader trimming brass question.

[folsoh]

Novice reloader here with some questions.

Ok I trimmed about a 100 new hornady 300 win mag brass too 2.610. Books says max COL is 2.620 and should be trimmed to 2.610. After chamfering and resizing they measure 2.614 to 2.615. All 100 empty cases measure in this ball park

Then I trimmed about 50 once fired hornady brass using the same trimmer (Lyman trimmer) and I guess something was not tight or loosen on the trimmer. After chamfering and resizing all of these measure between 2.605 to 2.607.

SO I have a few questions are the ones that are shorter by .005 at max safe to use? Or should I count my losses and pitch them? When is says trim to 2.610 should you always trim a little longer then chamfer???

Will there be much difference in accuracy between a 2.615 and 2.605 reloaded bullet if everything else is the same?

Would you keep the shorter ones separate from the longer ones for accuracy reasons?

Anyways thanks for your time and your knowledge is appreciated!!!!

 

[badkarmamib]

First off, you should trim AFTER sizing, not before. Then, all of your brass should be the same length.

 

[Grumulkin]

Besides not trimming after sizing, the other mistake you made was in sizing new brass which is a waste of time.

And no, you don't need to discard the brass and the difference in accuracy with minor variations in length such as you note, probably won't be noticible.

 

[folsoh]

I guess where I got thrown for a loop is in the Hornady Reloading manual 9th edition under reloading step by step it list case trimming before chamfering and deburring then lubrication and resizing.

I realize the advice of resize then trim makes better sense.

 

[kcofohio]

Besides not trimming after sizing, the other mistake you made was in sizing new brass which is a waste of time.

And no, you don't need to discard the brass and the difference in accuracy with minor variations in length such as you note, probably won't be noticible.

I tried to load some Federal Eagle (LC headstamp) once without sizing. I ended up with very little neck tension. It may depend upon who made them. I have only had a small sampling.

 

[otrman]

If you are one of the top 1% shooters in the world you might see a difference in accuracy. I would keep them as a separate lot first because they are once fired, second being shorter(they will catch back up).

To get the most life from your brass get this, http://www.larrywillis.com/. FL sizing dies do not get the area just above the belt and the case grows there too.
Belted Magnum
Collet Resizing Die

 

[Shawn Dodson]

Besides not trimming after sizing, the other mistake you made was in sizing new brass which is a waste of time.

Sizing new brass allows the expander ball open up the case mouth/neck and smooth out peening in the case mouth caused by the new brass being tumbled by the manufacturer, both of which reduce bullet seating resistance and the risk of buckling the shoulder when seating bullets.

 

[entropy]

What kind of bullet are you shooting that only sticks out .010? COL (also sometimes noted as OAL or COAL) is Cartridge OverAll Length. This is the measurement from the base to the tip of the bullet.

Here's a snippet off Reddit that clarifies that. (hopefully)


COL refers to "Cartridge Overall Length" not "Case Overall Length". (length of bullet + case after the bullet is seated). Generally, the case length won't affect the COL because the bullet will always increase the cartridge overall length, also you typically don't need to trim straight wall pistol cartridges.

What I'm specifically curious is that the Hornady reloading manual lists Maximum COL (this is important when you're using magazine fed rounds, less important if you're using a bolt action and loading single shots). But for each load data they list a COL value. What I'm curious about is whether it's a nominal COL or a minimum COL (to meet SAAMI spec for pressure).

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Hoodie59 1 point 4 years ago

I read that as Hornady listing an OAL and a COL. In which case I assumed COL would refer to the case. My bad.

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greenboxer[S] 2 points 4 years ago

Oh, that''s one of the annoying things you'll run into every now and then.

COL = cartridge overall length

OAL = over all length

COAL = cartridge over all length

and they all refer to the same thing.

Anyways, if you're curious, I think I figured it out, the OAL values that Hornady lists for each particular load data is what they found to be the most accurate load COL/OAL/COAL. So when they list 9mm data for X bullet and Y COL, that's the COL you should aim for. (so they're listing nominal COL not minimum COL).

 

[JimKirk]

I just went to check my Hornady #9 .... and it does list in the step by step reloading ... Trimming, Chamfering and deburring before resizing !

Hornady really should rethink how they have that info listed ....

Hornady #8 does also .... I don't have #3 thru #7 .... but #2 lists it in the correct order ...

 

[Bart B.]

As long as there's several thousandths inch clearance from case mouth to chamber mouth when rounds are fired, and enough case neck to grip bullets securely, case length can vary as much as you want.

Case mouth clearance to chamber mouth has to be enough to prevent case mouths getting crimped into bullets from firing pin impact that can set case shoulders back a few to several thousandths. That makes case length grow a little bit.

 

[Reloadron]

Same responses I gave you previously:

Reading that it looks like you trimmed and then sized? You really want to do your resizing operation and then trim. When resizing the case length is likely to change so resize and then trim if you want uniformity.

The 300 Winchester Magnum does have a suggested trim length of 2.610" and if we look at the actual SAAMI specification the case length is MIN. 2,600" and MAX. 2.620" with the suggested Trim To being 2.610".

How much will it matter or effect accuracy? Likely not enough to notice in the average rifle. If you want to separate the brass then go ahead, it won't hurt anything but personally I wouldn't bother.

Ron

As to the Hornady 9th, yes, it can lend confusion:

Reloading Step by Step

1. Check List
2. Case Examination
3. Case Cleaning
4. Case Length Measurement
5. Case Trimming
6. Case Chamfering
7. Case Deburring
8. Case Lubrication
9. Resizing / DePriming
10. Batch Repriming
11. Powder Weighing
12. Powder Charging
13. Bullet Seating
14. Labeling
15. Cleaning Up

Yeah, I can see where the list order, especially with Step by Step would imply you Resize following Case Trim when it should be the other way around as case length can and frequently does change, especially with bottle neck cases during resizing. I haven't a clue why Hornady suggest the order which they suggest?

Ron

That would be about it.

Ron

 

[RussellC]

I tried to load some Federal Eagle (LC headstamp) once without sizing. I ended up with very little neck tension. It may depend upon who made them. I have only had a small sampling.

I always resize new brass. Everything I have read says to. I reload for semi auto, not bolt action, but I would size them for either. For semi auto, always.

Russellc

 

[Bart B.]

All I've heard and read about news cases being loaded with or without any resizing is about 60% in favor of doing it at least for case necks. That's to uniform their mouth and throat diameters for consistent bullet release force needed to push them out. Some new case necks are out of round, dented or both.

I've loaded new 30 caliber belted and rimless cases without any resize or prep processes and they're indistinguishable from resized fired ones trimmed to equal lengths. That's how commercial ammo's loaded, regular and match versions.

 

[mdi]

I haven't found a "perfect, 100% right" manufacturer of anything, especially mass produced machined metal products, so I size and trim all my new rifle brass...

 

[Sunray]

"...new Hornady 300 win mag brass..." Hi. BNIB brass rarely requires trimming. It does require checking for length. And it's best if it starts all the same length. That's more about the ending Cartridge OAL than anything else.
Trimming is not required every time you load 'em either. It's only necessary when the cases stretch longer than the max case length given in your manual. That's 2.620" for .300 Win Mag.
"...sizing new brass which is a waste of time..." Nope. BNIB brass is not ready to load out of the box. It requires checking for length(trimming as required only), FL sizing and chamfering and deburring. Case mouths are not necessarily round either.
"...measure between 2.605 to 2.607..." You'll have different OAL's, but those are not unsafe or too short. SAMMI spec says 2.620 -.020. The -.020 is the tolerance. So 2.600" is the minimum case length.

 

[Bart B.]

BNIB brass is not ready to load out of the box. It requires checking for length(trimming as required only), FL sizing and chamfering and deburring. Case mouths are not necessarily round either.

I disagree. Post 13, second paragraph.

How many of you have inspected BNIB ammo for consistent case length and deburring?

 

[FROGO207]

I always process new brass as if it is fired brass. Then I know it is as close to the same without fire forming as all my other processed brass. I generally do not anneal it then though. YMMV

I once purchased Lapua 303 BRIT brass and after checking it did nothing to it before loading.

 

[Blue68f100]

I disagree. Post 13, second paragraph.

How many of you have inspected BNIB ammo for consistent case length and deburring?

It all depends on who's brass. If it's the high end class brass like Lapua, it's ready to load. But I still inspect it. If it's run of the mill brass I process it like it's range brass. You would be surprised as to what defects you will find.

 

[Bart B.]

What's the accuracy difference across a .020" spread in rimless bottleneck case neck length from case shoulder to case mouth? That's what's important; to hell with case length as it's not an issue because the case head's not against the bolt face when the round fires.

 

[mdi]

Only a few things absolutely "necessary" in case prep. If you wanna take the time to check/trim brand new, off the shelf, NIB cartridges, then by all means do so. If you believe factory fresh cases are "good to go" then don't size/trim them. Argueing about the process s worth every penny it costs to read about it; zero! I tend to prefer consistency, and knowing what I'm starting with, so I size and trim my brass, both store bought and range pick ups. No question about my starting point, they be all de same. Does it make any difference where the hole appear on my targets? Prolly not, but in my head it matters...

 

[SASS#23149]

the other mistake you made was in sizing new brass which is a waste of time.

balony. I"ve had bullets fall into new,unsized brass. Sorry,vehemently disagree .