Case Trimming

rogerstv

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Joined
Jan 10, 2019
Messages
96
Location
south central IL USA
I use a RCBS Case Prep Station. Appears I am not careful enough with case neck reaming inside and outside. I try to hold cases perfectly vertical. But, I obviously lean them.

I measured cases after reaming and several have high sides/low sides. Some of these cases are less than the COL and therefore do not need trimmed for length. However, I am leaning towards trimming them enough to square the neck. Run out is minimal, in the 0.001's.

I am seeking maximum accuracy. So, I believe I know the answer is....yes, I need to square the neck.

What do you guys do? Is there a more accurate reamer that will square the neck each and every time?
 

MNbogboy

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Joined
Jul 14, 2009
Messages
701
Location
Northern MN
Assume you have the "universal case prep center" that includes the trimmer.
That trimmer should square the case mouths before you do your inside and outside chamfer.
Have you checked them for square before chamfering? Maybe your trimmer is not squaring them to start with.
You do not have to chamfer so deep that you pass the "squared" edge that the case trimmer gave you. The outside chamfer should just take off the burr left by the case trimmer. The inside edge should be tapered just enough to allow bullet entry but not come to a "sharp" edge.
 

rogerstv

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Joined
Jan 10, 2019
Messages
96
Location
south central IL USA
It is the Trim Mate. No squaring provided that I can tell.
I will check square on the next set of brass before prepping.
I may be running the brass a bit too deep.
Thank you for advice.
 

MNbogboy

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Joined
Jul 14, 2009
Messages
701
Location
Northern MN
Correct the trim mate does not have provisions for trimming to length or squaring.
How are you trimming to length? The case trimmer will determine how square the case mouths are.

The inside chamfer only needs to cut and add .003 to .006 to the case inside mouth diameter to be larger than the bullet itself.....if the chamfer reaches clean through the case wall thickness it could lead to problems like you are experiencing.
Personally I hand chamfer all my cases with a Wilson hand tool after trimming. It only takes a couple of light twists on inside & outside and does not remove much material. However unlike some I only shoot between 2000 and 3000 shots a year and volume is not a big problem for me.
 

rogerstv

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Joined
Jan 10, 2019
Messages
96
Location
south central IL USA
I just bought a LE Wilson case trimmer to replace a RCBS. I love the Wilson.

I have a RCBS hand tool. Will start using it instead of the case prep station.

I need to do some before and after measurements to find out where the issue originates.
 

Savage 12BVSS

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Joined
Dec 20, 2019
Messages
824
Location
Maine
Use Lyman trimmer and chamfer cases with the hand tool, never encountered angled case mouths. Maybe the trim station ?
 

shooter7

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Joined
Nov 29, 2011
Messages
479
Location
Missoula, MT
The most consistent trimmer I've used is the Lee Trimmer. The pilot/length gauge runs the entire length of the case and doesn't cut too short if you apply too much pressure. It is kinda slow though. My brass usually is broken into 50 or 100 round lots though. It just provides cheap, easy, repeatable results. Biggest downside is it's not adjustable.
 

elf

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Joined
Nov 26, 2017
Messages
257
I use the Wilson to trim and RCBS case station to champfer. I recently found the outside champfer was badly worn after 20 something years, and it was leaving burrs on case mouths. RCBS sent me a new champfer. I don't know why anyone would ream inside necks, but they can be turned. I would never ream necks inside because of fear of inconsistencies.
 

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