Neck turning: Trying to turn full neck but seeing cutting high on shoulder (280 AI)

[Mike Matteson]

Yes 21st does have a small curve to the transition to AI angle. I got my mandrel turned today to fit the ID of the necks. The 5 cases I am going turn the neck now, in couple of days. You definitely need to turn your necks before sizing your cases, otherwise you push the uneven neck thickness to the inside. The only thing I am thinking about is cut the necks to length first before cutting the necks for thickness. I may play with a case or two to see how that going to work out in having the exact length. I am being anal on case setup.

 

[1Moose]

Have you tried turning a unfired piece of brass to see if the same thing is happening

Thanks JMW. Yes, I turned five of them and they don't show the issue. The COAL is a touch longer, but the shoulder is farther back still as it hasn't expanded to my chamber yet. I cut the two worst cases apart to see if I could see any abnormalities. Will post that in a second...

 

[1Moose]

Thank you all for weighing in. I really appreciate it.

I wanted to see if there would be any visible thinning from the cutter contacting the shoulder. In particular, I'm wondering if a number of the 50 I turned would need to be scrapped. I used a thin cutting wheel on my die grinder and here's what the two worst cases looks like. I tried to position one to show the slight indention the cutter made in the shoulder-body junction of the case. I can hook a fingernail on that, but it is doesn't show on the photo or to my eye. To me, it seems the brass thickness is normal, but I don't want to be be cheap and create a dangerous situation (or harm the rifle). Any thoughts (in addition to keep farther away from the shoulder with any future neck turning adventures)?

 

[Bob Wright]

I've turned a lot of 280AI in Nosler and some new Petersen brass. I really don't see anything preventing you from shooting these. I've seen a lot of "non-cleanup" in the neck shoulder junction with Nosler simply because the brass is thinner than Petersen. As long as your cutter just makes contact or. 001 into the shoulder you should be good.
My cutter is 43° used on a 40° shoulder. Meaning it will cut the radius first at the neck shoulder junction (fillet radius) as opposed to one big bite on the shoulder. You want to just get into the radius everytime with some here and there that may not completely clean up anyway. No biggie if your setup is blending into that radius most every time.

 

[1Moose]

I've turned a lot of 280AI in Nosler and some new Petersen brass. I really don't see anything preventing you from shooting these. I've seen a lot of "non-cleanup" in the neck shoulder junction with Nosler simply because the brass is thinner than Petersen. As long as your cutter just makes contact or. 001 into the shoulder you should be good.
My cutter is 41° used on a 40° shoulder. Meaning it will cut the radius first at the neck shoulder junction (fillet radius) as opposed to one big bite on the shoulder. You want to just get into the radius everytime with some here and there that may not completely clean up anyway. No biggie if your setup is blending into that radius most every time.

Thank you Bob. I appreciate the help. I'll get some loaded to shoot and will be interested to see how things progress. I'm looking forward to comparing how the concentricity of these once-fired cases compares to that of five never-fired cases I also neck turned. I wasn't planning to get into turning necks, but I now have an experiment in the making. Thank you.

 

[can1010]

Sinclair sells a 40 degree cutter separate. it will solve your problem

 

[1Moose]

Sinclair sells a 40 degree cutter separate. it will solve your problem

Hi can1010. I was actually using the 40 degree cutter they sent, so that was part of what made this interesting.

 

[ButterBean]

Here's an up close photo that I think shows it. It's as though there's a very slight bulge at where the shoulder and sidewall meet and the cutter is taking that down a bit. Maybe the brass simply didn't spring back there as much after the sizing operation?View attachment 320189

You just need to grind a relief on your tool where its hitting the shoulder and you'll be good to go

 

[ButterBean]

Sinclair sells a 40 degree cutter separate. it will solve your problem

Or this

 

[1Moose]

Or this

Thanks Butterbean. Interestingly, I'm using the 40 degree cutter already (or at least what Sinclair sent as one—they aren't actually labeled but it looks right—at a minimum it's steeper than the standard cutter). If I continue to see this I'll consider if an even steeper cutter might be available, or as you suggest modifying mine if I can. The other option would be to be conservative with how close I get to the neck-shoulder junction though most of what I've read says I want to get up close)

 

[can1010]

I have done a lot of 35-40 shoulders and the only time i did that was after doing 308 win and not changing the cutter back. they dont mark their cutters and your pic showing it hitting the shoulder isnt right, my cutter 40' cutter never touches the shoulder

 

[ButterBean]

Thanks Butterbean. Interestingly, I'm using the 40 degree cutter already (or at least what Sinclair sent as one—they aren't actually labeled but it looks right—at a minimum it's steeper than the standard cutter). If I continue to see this I'll consider if an even steeper cutter might be available, or as you suggest modifying mine if I can. The other option would be to be conservative with how close I get to the neck-shoulder junction though most of what I've read says I want to get up close)

You will want to cut all the way down to the neck, Just take a Dremel or a piece of sandpaper and sand it down, Easy Peasy

 

[1Moose]

You will want to cut all the way down to the neck, Just take a Dremel or a piece of sandpaper and sand it down, Easy Peasy

Dang Butterbean, I just realized from your post quoting JE Custom that it appears we have lost him. I was absent from here for quite a while. I didn't know him, but I've benefited from his advice on this forum.

 

[Mike Matteson]

I agree with ButterBean on where to stop the cut. In setting up my 6mm-280AI. I have found these problem so far. I have found that the ID in the neck area from case to case varies some. So I had the mandrel cut to allow the necks to fit the mandrel. COAL of the case varies some too. The 10 cases I checked varies .0065 from short to long in length. What I have read over the time that case COAL matter too. So I am going to set up and cut the case to length before doing anything else. These cases (500) are brand new and never been fired. I have the equipment to do the work, but didn't have the case until last week. So I have been held up for quite sometime wasn't able to explore and adjust the items I need until now. That alright, because the equipment has taken some time to acquire. Now getting into the finer parts of this operation. I think there will be other mandrels work that will need to be done.