Novice reloader brass trimming ???

F

folsoh

New member
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!!!!
 
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.
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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
 
I had the same apprehensions when I first started reloading .223 rem. The short answer to your questions is that your brass is safe to use as it's nearly impossible to get your brass trimmed to a perfect length every single time. +/- .005 inches isn't going to affect much.

That said, you should really resize your brass before trimming. Not from a safety standpoint, but brass can/will stretch a bit during resizing.
 
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.
 
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.
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If they were talking about straight wall cases you could probably get away with doing it in that order.

I resize all new brass, then trim, chamfer and deburr.
 
Lots of bench loading experience taught me that trim length isn't a huge factor in accuracy, as long as you aren't using a hard crimp.

The neck is there to hold the bullet centered with the bore & that's about it.
Neck does some sealing but the bullet is long gone by the time that happens,
So holding the bullet off the rifling and keeping it out of the case, holding it centered with bore pretty much sums up the job of the neck.

As long as it holds the bullet in place, is centered, and isn't long enough to run into anything, you are usually real good.
 
Yeah, you have a good point there.
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.
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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
 
RC20:
I would not even publish that list.


Resize Before Trim!
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While I agree it is easy to see how a new reloader could become disorientated or confused. The list was verbatim from the Hornady 9th Edition Handbook of Cartridge Reloading. Why Hornady published in that order I have no clue.

Ron
 
After sizing and decapping you can either wipe down the brass individually with warm soapy water and an absorbent cloth or run them through the tumbler with older media that is not treated. Either way should remove the lubricant. You definitely don't want lubed cases being fired in your gun.
 
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