Runout in lubesizer

[Trailblazer]

I sized some RCBS 180-FN in my Lyman 450 this morning and noticed something I hadn't seen before. The top driving bands were only contacting one side of the size die. The RCBS 180 has a fairly long bearing section and cast between .309" and .310". I was sizing in a .310" die. The lower drive bands were evenly polished by the die so the bullets look to have entered the die in the center but the ram must be out of line with the die.

I tried another 30 caliber bullet and a different top punch and got the same result. Probably not good for accuracy with bullets that have a long driving surface. I suppose it could be the die. Might try rotating the die 180 degrees.

Suggestions?

[Bullshop]

Pre size nose first, then size/lube. That will most likely correct the problem.
Takes about 2 minutes to modify an RCBS/Lyman sizer to nose first push through, and about the same to change it back. And dont lock that TP in so tight, just enough so it wont fall out.
Blessings
BIC/BS

[cbrick]

Several years ago I did a comparison of sized concentricity with the RCBS, SAECO and Star lubri-sizers using an optical comparator at a friend's machine shop. The boolits sitting on a grid and the scale blown up like a microscope and the differences were shocking. The RCBS and SAECO had little difference but accross the board the Star boolits were surprisingly more concentric. Looking at the edge of the front driving band in good light as you did is what got me into this experiment.

I doubt that with today's machine tools and mfg practices that the die and ram are much out of alignment, more likely is the original engineering design of this type of sizer vs the push through design of the Star. The nose first push through Star gives more consistent concentricity than the two other machines I compared it with and is the prime reason its the machine I use.

Rick

[fishhawk]

i actualy just hold the top punch in with a dab of lube so it can center on the boolit nose when the set screw is tightend down it's off by .003 there abouts, just for the needed differnce in the pilot shank and the hole

[WyrTwister]

Several years ago I did a comparison of sized concentricity with the RCBS, SAECO and Star lubri-sizers using an optical comparator at a friend's machine shop. The boolits sitting on a grid and the scale blown up like a microscope and the differences were shocking. The RCBS and SAECO had little difference but accross the board the Star boolits were surprisingly more concentric. Looking at the edge of the front driving band in good light as you did is what got me into this experiment.

I doubt that with today's machine tools and mfg practices that the die and ram are much out of alignment, more likely is the original engineering design of this type of sizer vs the push through design of the Star. The nose first push through Star gives more consistent concentricity than the two other machines I compared it with and is the prime reason its the machine I use.

Rick


How about the Lee push through sizers ?

God bless
Wyr

[xtimberman]

Pre size nose first, then size/lube. That will most likely correct the problem.
Takes about 2 minutes to modify an RCBS/Lyman sizer to nose first push through, and about the same to change it back. And dont lock that TP in so tight, just enough so it wont fall out.
Blessings
BIC/BS

Are you saying that all you have to do is install a flat top punch to push it in nose first. Should the GC be put on for the nose-first pre size? I've been wondering about these two things with long skinny bullets.

It would probably help if that sizing die wasn't locked down tight, too.

Thanks,
xtm

[Bullshop]

No thats not what I am saying. What you have to do is ,remove the depth adjuster and lock ring, remove the die from the press, and remove both ejector pins(one in die, one in press). Put the die back in the press, Then with a flat TP or something smaller than the base you can push them through nose first and catch them from the bottom.
Takes about 2 minutes to do and undo. Makes a BIG differance!
Blessings
BIC/BS

[xtimberman]

Bullshop,

Thanks a lot for the full explanation!

xtm

[Buckshot]

................Trailblazer, with that 30 cal die in place and a 30 cal nosepunch, run the ram down till the nose punch almost enters the die. Is it co-axial with the die? Most wear in the casting the ram passes through allows a front to back wear pattern, and the nose punch will be biased toward you or away from you. With play in the casting, how you opperate the handle could also have the ram displace sideways also.

The RCBS press is better then the Lyman but both can develop accuracy issues. There is a great writeup here: http://castboolits.gunloads.com/showthread.php?t=26400

On rebuilding one. A better press that might cost another $10 for the mods would be if there was a bronze bushing a hard chrome plated ram rode in. Add a lubeable felt collar wiper around the top of the bushing to exclude abrasives and it would last forever.

.................Buckshot

[cbrick]

WyrTwister,

I've never used the Lee dies because I have the Star though I have recommended them many times. I would think that with a flat punch and sizing nose first the Lee should work as well as the Star for concentricity. When I size in the Star without lubing I use a very small amount of Hornaday case lube on my fingers, since the Lee doesn't lube using such a method could/would be beneficial.

Rick

[Trailblazer]

The ram is pushing the bullet to starboard. I had about 50 bullets sized when I saw it and verified that it was consistent. I will try Bullshop's idea and then compare the two at the range. I also have another Lyman 450 that is missing parts of the linkage. Maybe it is more concentric.

The rebuild article is a good read! Might have to try that too, since I have an extra 450.

[OeldeWolf]

Did anyone ever hear if KNT ever finished the luber design he was working on? Here is a link to his thread, back in 2006

http://castboolits.gunloads.com/showthread.php?t=11113&highlight=sizer

[Buckshot]

...............Dunno if he did or not. He's posted on the swaging forum, and he DID say he had lots of projects so nothing is getting done soon :-) It may be on the 3rd shelf down in the "To Do" closet?

................Buckshot