.309 RCBS sizing die undersized?

[Mark Daiute]

Have any of you EVER recieved and RCBS die that was under sized? I have an older Lyman die but don't like the arrangement of the lube holes in the die so I picked up and RCBS .309 die off of Fleabay.

First thing I noticed was the undue pressure required to size the same bullet, a lee 120 grain 30 caliber bullet for my M1 Carbine. Second thing I noticed was that one side of the bullet was sized all the way up to what I think you call the ogive. Parts of the sized bullet were measuring close to .308.

Just wondering if anyone else experienced this.

Mark

[btroj]

Final size is a factor of the size of the hole AND the alloy used. Harder alloys spring back some after sizing and can give larger final diameters.

If one side is sized more than the other then either your sizer push the bullet to one side or your mould is throwing out of round bullets.

[Mark Daiute]

Bullets sized in the Lyman .309 die exhibit none of these characteristics and the bullets sized in it perform admirably.

[GBertolet]

I believe the industry tolerance standard is + or - 1/2 thousandths on diameter. As previously mentioned your alloy has an effect on final diameter also. I have a .309 die and and a .310 die. Both size to .3095. Minimum tolerance on one and maximum on the other. I found overall that the Lyman and RCBS diameters run pretty close to advertised size, while the recent Star-Magma dies are way undersized. At least the last few I purchased were. Even the test bullets included with the dies were undersized, usually around 1.5 thousandths. No big deal, as I lapped them out to the desired size myself.

I agree that the uneven size marks are most likely due to an out of round bullet.

[leadman]

It is possible to get the die offset in the RCBS luber/sizer. Don't know about the Lyman machine. This can cause the boolit to be sized off center.
Try loosening the hold down nut and find a top punch that is just the right size to enter the taper in the die. Install it in the ram and lower it in the die. This will align the die to the ram. Tighten the nut with the top punch in the die. A 7/8" nut can be used as a spacer if you need the room to get a wrench in there.

Also the old style sizer dies had no taper leading the boolit into the die and would do what you described. If this is the case you can use a dowel and emery paper in a drill to taper the top of the die.

[Mark Daiute]

Leadman, thank you for the good info. I am using this die in a Lyman 45. I will check to see if it has a taper or not.

The only issue I had with the Lyman die was lube flow.

[RayinNH]

Mark ,does your top punch fit your boolit well so the it doesn't tip upon entering the die ?

[Cimarron Red]

Mark,

Check the top surface of the ejector pin in that die. I have had two where they had been cut at an angle. RCBS will send you a new one if yours is angled.

[Mark Daiute]

Mark,

Check the top surface of the ejector pin in that die. I have had two where they had been cut at an angle. RCBS will send you a new one if yours is angled.

Thank you Mr. Red. Did you have the same symptoms?

[Cimarron Red]

Yes I did, Mark. Over the years I've had two dies with pins cut at a slight angle -- a .309" and a .311". When I first phoned RCBS to tell them of the problem, the CS rep. explained that my pin had been made with the end portion of the rod they used to make the pins. Seems odd they wouldn't check that because it seems to happen frequently enough.

If you chuck the pin into a drill press, and turn it against some emery cloth, you'll likely be able to true it up. But RCBS will send you a new pin.

[Mark Daiute]

Yes I did, Mark. Over the years I've had two dies with pins cut at a slight angle -- a .309" and a .311". When I first phoned RCBS to tell them of the problem, the CS rep. explained that my pin had been made with the end portion of the rod they used to make the pins. Seems odd they wouldn't check that because it seems to happen frequently enough.

If you chuck the pin into a drill press, and turn it against some emery cloth, you'll likely be able to true it up. But RCBS will send you a new pin.

I'm fighting the urge to address you as C.R.. Thank you for your help on this, the explanation makes perfect sense and it is truly appreciated.

Happy thanksgiving,

Mark

[Cimarron Red]

Hey, Mark,

You're certainly welcome, and CR is perfectly fine. With my pin I checked the cut on the top with a machinist's square. But next I stood the pin on its top end on a small steel plate I have mounted on my bench. It looked like a tiny Tower of Pisa! Your off-center sizing may have a different cause; mine was cause by the angled pin cut. Good luck, and Happy Thanksgiving!

[Mark Daiute]

CR got me thinking along the right lines.

I'll swallow my pride, display my foolishness so that others may benefit.

Long story short: the ejector pin was in the die backwards!

Turned it (the ejector pin) around and voila! happiness in lube-sizer land and the lube flows just like I'd hoped it would.

And that, as they say, is the rest of the story.

Merry Christmas, Happy Hanukkah and all the rest. Oh and happy new year. May we all have lots of range time.

[dondiego]

Don't forget that you can alter the lube flow in the offending die by plugging holes with lead shot.