case trimming question

[sithlord6512]

I just started trimming my .300 WSM cases with my brand new Sinclair trimmer. I followed the instructions provided with Sinclair NT-1000 case trimmer to a "T". After trimming 12 cases, I noticed that about half-way up the shoulder on 6 of them, a small, thin shaving of brass from the shoulder was was taken off (the "length of this shaving was slightly less than half the circumference of the shoulder - the remainder of the should was untouched by the cutter). Should I discard this brass? Thanks in advance for any advice.

 

[old #7]

I am not familiar with the Sinclair trimmer. It sounds like you took some meat out of the shoulder instead of or in addition to trimming the neck.
I would discard the brass if the shoulder was cut.
A picture would say a thousand words.

 

[30-338]

I just started trimming my .300 WSM cases with my brand new Sinclair trimmer. I followed the instructions provided with Sinclair NT-1000 case trimmer to a "T". After trimming 12 cases, I noticed that about half-way up the shoulder on 6 of them, a small, thin shaving of brass from the shoulder was was taken off (the "length of this shaving was slightly less than half the circumference of the shoulder - the remainder of the should was untouched by the cutter). Should I discard this brass? Thanks in advance for any advice.

http://www.sinclairintl.com/.aspx/pid=3 ... urning_Kit

I assume your turning necks and hit the shoulder with the cutter. Your neck length is varing to cause that and if you using the mandrel to stop the case I'd back that of some and stop the case before the shoulder/neck and not use the mandrel for that. Hope that helps and I'd toss the case

 

[rick smith]

How would you touch half way up the shoulder and not touch the remainder? You turning necks? Is the shaving off the neck and not the shoulder? How thick is the shaving?

 

[JD338]

sithlord6512

Can you post a picture so we can get a better understanding?

JD338

 

[30-338]

I just started trimming my .300 WSM cases with my brand new Sinclair trimmer. I followed the instructions provided with Sinclair NT-1000 case trimmer to a "T". After trimming 12 cases, I noticed that about half-way up the shoulder on 6 of them, a small, thin shaving of brass from the shoulder was was taken off (the "length of this shaving was slightly less than half the circumference of the shoulder - the remainder of the should was untouched by the cutter). Should I discard this brass? Thanks in advance for any advice.

If your using the neck turning NT-1000 I'll try an make this simple. One flaw with it is the bevel at the start of the cutter is cut square most other are rounded. Depending on angle of shoulder of the case we all neck thickness varies that same thing happens on the shoulders you are hitting the end of that square angle cutter on those high spots. Thats the reason of the thin shaving you mention it's the point of that angle.

I would make sure all neck length are the same and adjust stop if your using the mandrel so that point doesn't hit the shoulder angle. I use a bushing die that sizes the outside of the neck down to the shoulders and expander mandrel to open the necks up. I also switch for a NT-1000 to K&M and Hart neck turner.

 

[sithlord6512]

Sorry for causing confusion - I meant neck turning (not case trimming).

I believe 30-338 got it right. As I trimmed the cases to minimum specs for a .300 WSM (2.090) using an theRCBS case trimmer, I am certain the shaving I am taking off the shoulder is not due to an uneven case length (assuming my neck trimmer is cutting sqaure - I have no reason to believe that it isn't).

I know that the cases had over .0015" case-neck thickness variation (some even up to .0040 variation). Intuitively, the shoulder area must also have greater than .0015" variation (the same variation found in the necks).

As suggested, I suspect the angeled edge of the cutter - the part that is apparently normally rounded on other next turner cutters - is taking off the high spots in the case shoulder. I noticed that the bottom edge of the cutter blade is not perfectly parrallel to the neck turning mandrel - the back portion of the cutter is higher than the leading edge of the cutter. this is consistent with the fact that the leading edge/corner of the angled part of the cutter (the part that is not supposed to be cutting anyting) is the part that is cutting the shoulder.

I culled these cases initiatially because they exceeded the .0015" case-neck thinkness variation that John Barsness recommends for Hunting Ammo. I ordered the Sinclair Neck-turner in hopes of bringing these cases to the recommended specs (the cutter is set to cut neck thinknesses to .014").

I have backed off the mandrel so that will not cut the shoulder - I should have the problem anymore. However, back to the initial question - should I discard the cases that have the shaved shouders. The approximate width of the shaved sections are about .75 mm (or .0295 inches), with the length extending just under half the circumference of the next shoulder. I can only guess that the thickness of the shavings are between .0001"-.0025" (the same variation that would be trimmed off the necks). I suspect that the answer is yes, but I am naturally a pessmisstic and perhaps overly cautious type of person. thanks.