257 Roberts Sizing Problems

[Tdart]

Hello all,

I'm in need of some advice. I am working up some loads for my Ruger M77 ultralight in 257 Roberts. I started with PPU 7X57 brass and ran them through my RCBS sizing dies with no trouble. I loaded the brass 2 times, both with somewhere between 35 & 37 grains of IMR 4064 behind a 110 grain accubond. The problem is that on the third reload, the neck seems to be very tight. When I bring the brass up into the die, the upstroke is very smooth and relatively easy. The down stroke is smooth until it reaches the neck sizing "ball." At that point it is extremely difficult to bring the brass the rest of the way. So difficult in fact, that it causes dents in shoulder of the brass (see picture). It does not do this with new brass. I am using lee cases lube, and I double checked with a new case, so the lube isn't an issue. Could they have "Work Hardened" after just 2 rounds? The brass was not subject to excessive pressure from what I can tell. The 37 grain load is above the max for a standard Roberts, but is below what a +P would be, and I was only average 2780 fps with that load. Any thoughts? As always, I appreciate your help.

http://i588.photobucket.com/albums/ss328/ttdart/IMG_5475.jpg (http://s588.photobucket.com/user/ttdart/media/IMG_5475.jpg.html)

[bullet maker 57]

Have you annealed them?

[Tdart]

I have not annealed them. I've never had the need before, so I haven't started.

[danomano]

May not help, but try to raise the sizing die up a touch, and try a few more.

oh and less lube may be it too. and try cleaning the die out too.

[Wayne Smith]

Have you lubed inside the necks? I have a medicine bottle full of shot that I dumped powdered graphite in. Dipping the neck into the shot lubes inside and outside of the necks.

[Tdart]

Have you lubed inside the necks? I have a medicine bottle full of shot that I dumped powdered graphite in. Dipping the neck into the shot lubes inside and outside of the necks.

Yes. I used lee case lube on the necks. When I pulled the expander ball it, it had sufficient lube on it and was clean. Could the dies be lowering the neck diameter too far?

[Bret4207]

The dents you have are absolutely classic examples of lube dents. You have lube up in the die, either from the manufacturing process or more likely a little extra from when you lubed them. Clean the die and the dent should disappear.

The dragging can be a couple of things. First it can be simple friction. The neck is smaller after sizing than when you started, so the expander is going to open the neck back up. It's supposed to do that. If the expander ball has a rough finish, and you get that with most brands every now and then, you can polish it a little to help. Don't go crazy doing that because polishing means your removing some diameter and you need that, specially with cast. You can also try lube. Dry lubes like graphite work great, but I've used a little bit of case lube in the past, just have to wipe the case neck inside afterwords. Another cause can be the "dreaded donut". That's a heavier ring of brass that collects at the shoulder.neck junction through sizing and it's usually takes several loadings and FL sizing to create. Its a bit more complicated than just that, but I doubt it's that. Work hardened brass is stiffer than soft, freshly annealed brass and you'll feel the difference going over the expander. That usually takes at least 3-4 loadings, often many more, to notice. But, I've seen some brand new brass out of eastern Europe that was pretty darn hard from the get go. Annealing should be covered in most reloading manuals. If yours doesn't have it, let us know, it's not hard.

So, clean the dies, don't over lube the cases and look into a lube for inside the neck and you should be back on track. Oh yeah, if you cases have stretched a lot that can cause it too, so measure the case length and see if they need trimming.


ETA- I just re-read your post. You are using reformed brass! Did you trim for length after forming? If not, check that ASAP. Also, you just moved up a notch in the "dreaded donut" category. Take a paper clip or something like it and gently run it down the inside of the neck. Near the shoulder.neck junction pay close attention- if there's a bit of a hump there...that's the donut. Inside neck reaming is the cure. Also, PPU brass is European or Rooshin? Might want to look into annealing.

[1hole]

Those are lube dents.

Expander drag during withdrawel can be eased with inside the neck lube but it isn't neccessary, just pull the thing out.

[MarkP]

Lube dents; when cleaning out die check the vent hole with a toothpick, may be plugged as well.