Lee Loader

A "deep chamfer" will help . With uncertain brass I have a 20 mm AP drilled and tapped 1/4-20 that I use to polish and flair the case mouth the first time . I run it in a drill press for a reasonably consistent stop . Best part is that it works from 22-45 cal , I don't have any bigger or smaller calibers to try it in .
A flair big enough to start the check and small enough not to hang on the neck of the seating die is the ticket .
Unless you're using a very hard alloy I would avoid more than just barely over removing the flair .
Many cast shooters have boxes of factory expander balls and dies full of customs and/or borrowed from other sets . This is to better fit the cast . I have a 6.8 Rem with a "polished fitted" 7mm expander in it for a finished neck ID of 278 for the 280 dia bullet . My 7mm takes a 286 so the custom ball finishes at 284 vs 281 .
I have a 7.62 that is huge . The bore is .3165 and the fired case will press fit a .323 , .318 shoots well enough for what the rifle is but the RCBS dies only come with neck balls for 308 and 312 so a custom knocked out on the drill press for .316 does the job.

NOE has tapered expander and Lee will make custom powder through expanders as noted by Ranch Dog.

On my 30-30 I use an expanding/ flaring die. Very simple design. I am in the process of making another one for 6mm for my 243. It doesn't take much flare to get the bullets to slide right in. Glad you have success.

GasGuzzler wrote:NOE has tapered expander and Lee will make custom powder through expanders as noted by Ranch Dog.

Lee also has a "new" universal expander that gets high marks in reviews.

Thanks Horseman!!!
That is exactly what I was looking for - Lee is not showing it on their web site easy to find...
But I found it... Universal Case Expanding Die SKU 90798
Universal Case Expanding Die

You can find it on A-zon under... Universal Flaring Die

Love it, keep us posted.

I have a related question. Keep in mind that this is me reloading rifle cartriges for the first time so some of the things are somewhat unusual.

How deep should it insert the bullet?
There is no specific data for it for Lee's C285-130 with Lee's dies or in Lyman manual - that one has data for much larger bullet. In this picture I've got the calipers open to MOL (3.0") and the bullet layed out next to the cases to match different lube/crimp groves.
The top one would be way to deep - the gas check is past the neck - no good.
The middle one is deep but the gas check is on the edge of the neck - I don't think that's good either.
The bottom one would keep the gas check inside the neck but only one lube groove in the neck. It also does not have a lot of bullet in the neck.

All of them are below MOL with the max length of 2.9" (matches Lyman spec for larger bullet).

My questions are as follow:
1. Should I use the bottom config (one lub groove in neck)?
2. If so, is that enough lube for the bullet?
3. Or maybe should I go between the middle and bottom and crimp between the grooves? I like this option...
4. Once loaded, can I clean up the visible part of the bullet with mineral spirit to remove the lube? Should I just gently wipe it not to disturb lube in the groove?

This is actually and easy one . Increase the depth until the bolt closes with light contact pressure but not so firmly that it pulls the bullet .

The ideal is with the gas check in the neck . That's not always possible .
I have a couple that can't be seated that way at either extreme . 1 due to leade OAL requirements . 2 due to the GC being barely in the case neck due to long throat and leade length and 3 because of magazine requirements .

In a perfect world set up the front or top band or area above the crimp groove will be contact slip fit in the throat and 25% or more of the nose will touch all of the lands or be equally spaced off of the lands AND the lube grooves will be covered AND the gas check will be above the bottom of the neck .........
I have 2 moulds for 3 bottle neck cartridges that actually work out like that . They were designed specifically for those cartridges in that chambering or for a sister cartridge with a shorter neck and longer throat/leade area .

If everything fits in your 7x57 bbl then seated to the crimp groove should do the job .

Finally, I was able to make a nice batch of bullets and take it to the range.
I made 6 sets of bullets, 7,8,9 grain of Unique with 2nd and 3rd lube groove bullet seating.
All made similar grouping at 50 yards - about 1.5-2" (yah, I suck at shooting rifle - for now, I hope )

I put a chronometer in front of the rifle and here are the results: What I find odd, is that I have, by far the highest speeds at lowest powder loads - 7grn, lowest at 8grn and midrange at 9grn. No, it is not due to compressed load - I'm at about 20% capacity.

So I have 2 questions:
1. Why the odd speed relationship to powder load?
2. Considering that this is a 100-year old Spanish Mauser, can I use the configuration from first column (7/long) or should I assume that the pressure would be lower in column 3 (8/long) - I don't want to over-stress the rifle unduly. This is just for target shooting.

File this under "Unique".

What did primers look like on 7/short? Were they tough to extract? Sure is the outlier with bad ES. I wonder if you had chrono fail on 7/short.