I've started using a Lee collet neck die for my .270 brass. I've just noticed that the cases are sized .003" smaller in diameter at the mouth than the rest of the neck. I've used the die as Lee recommends and also set it up the way Mathman has suggested and it doesn't seem to matter. Is this the way the die is designed to size the neck? I assumed the entire neck would end up the same diameter.

Are you referring to inside diameter, or outside diameter?

Outside.

Make sure you are not jamming the mouth up into the die. Back off a quarter tern and measure again. I also deburr and polish the collet fingers so it doesn't mark cases. The fingers fit together better after this. I also polish down some of the machining ribs or marks then some auto re assembly moly lube sparingly applied and the entire operation is much smoother. First time I tried one in 375 I was waiting for that partial "toggle over" feel and blew the cap right off my brand new die and jammed the case. Boy was I disappointed. Threw the die to the back of the bench and left it there for a couple of years. Will send back to Lee and I bet they send me a new one maybe with a PS " your an idiot" but probably not.

I really like them now I am over the dumbazz curve.

Glad I 'm not the only one to pop that cap! Ordered several spares, since the cap is the same for all of them. Not easy to get all that AL-U-minny-um out of the threads, though.

Now, I only use them in my hand press, mainly .22 Hornet. I also use regular Lee Loader dies for new brass at times. Easy-peasy loading.

Is this the only batch of brass you've sized and measured with this die? I've run into brass where the necks tapered in thickness from thinnest at the mouth to thickest near the shoulder.

I was wondering about that. Yes it is the only brass I have measured with this die. I didn't know if neck thickness could taper and if .003"+ was abnormal or not. This batch is Federal brass if it matters.

Also Mathman, with your method of setting up the die, does the press cam over right at the very end of the stroke?

Cam over or not depends on the press. If you go through my method the cam over won't pop caps off the die or overdo things.

Neck thickness surely can taper. When I've been turning necks and the mouth end isn't touched and the base end is cut all around it makes it plain.

Yes, it can easily taper that much. I've run into a fair amount of brass that tapers in the neck area, it readily shows itself when neck turning it.

I think mathman sets them up the same way I do. My rockchucker cams over right at the end of the stroke when I have them set up the way I like. I set them by feel, I've learned what the proper force feels like so it'll cam over without blowing the top off the die.

Thanks fellas. That eases my mind.

Your brass could probably use an annealing cycle. It's not unusual for the mouths to flare or constrict depending on how much stress is in the material. The very end of the case runs out of support so the stresses are able to affect the diameter at the tip. Inside of outside chamfering can usually take care of small discrepancies.

I had just annealed the brass prior to sizing.

I thought popping that cap was a mandatory part of the training. Lee was kind enough to send me one at no charge (except shipping).

Is everybody out there ham fisted?

personally I cannot stand the standard Lee Mandrel's I think that they are too big.... I have sanded down all my standard Mandrell's another 1.5 thousands of an inch or I have ordered them direct from Lee. I know get what I definitely think is the proper tension without having to crank the heck out of my handle on my press... and beat up the sleeve on the die. When I set up the die I only measure on the inside of the case mouth and neck I never worry about the outside dimension... and often there is a ridge near the case mouth that is not removed by outside deburring which can throw your Dimensions off an easy .001 to .002 in.

Yeah, i had some issues with some Winchester cases not being sized down enough. I've read about other people having the same issue. I was barely getting .001" of tension. The bullets seated and pulled very easily. On a whim I took a cartridge and pushed the bullet tip against the side of my bench. I was able to push the bullet in a few thousandths with just firm pressure. The cases were on their third firing after annealing. Maybe they just needed annealing again if i didn't do a good job the previous time around. I didn't want to sand on the mandrel or order a smaller one until I had tried different brands of brass and some annealing first.

If you have spares on hand, you are not likely to pop the plug. I have four or five spares here someplace but have never needed one. I guess that shows that you don't even have to know where they are.

Be suitably grateful, please. We exist to make you look good.🙄

A lot of Euro brass is tapered. Let us know how it works out. But once you dial it in the Lee die works all out of proportion for the cost. There is always that d-azz problem for me but a little testing usually can work this out.