Accuracy - Sizer Alignment

  • Last Post 28 April 2020
  • Topic Is Solved
Bud Hyett posted this 24 April 2020

 I fear I may be chasing a factor hard to measure and analyze. 

Many years ago at the NRA Annual Meting in Long Beach, CA, I had a long discussion about the manufacture of the RCBS Lubri-Matic sizer alignment between the top ram and the sizing dies in the body of the unit. The RCBS manufacturing engineer was there and was full of information. He said RCBS had just bought a specialized tool to cut both bores in the casting on one operation to assure alignment. This was good information to me since he said their goal was holding the tolerance +/- .001 to assure straight sizing.

Later, in a discussion with David Lee at a Clark Rifles match, he disclosed that his testing showed the greatest elimination of flyers was nose first sizing. His testing showed this approach eliminated more flyers. Therefore, I went to sizing nose first in a Star lubrisizer. The thought is the bullet is sized in the same way it enters the rifling from the leade and goes down the barrel with less stress.

In addition, the top punch has slop in the mounting that could affect how the bullet aligns. Pushing the top punch tight against the far side of the top ram can pull the nose off center as it is sized. Not much, but sill a factor in alignment. 

Has anyone tested the scenario of nose first sizing versus base first sizing?  

Has anyone tested the alignment of the top punch?

Farm boy from Illinois, living in the magical Pacific Northwest

Attached Files

  • Liked by
  • John Alexander
  • Ross Smith
Order By: Standard | Newest | Votes
cbshtr posted this 24 April 2020

I never tried nose first with my Lubri-Matic, I have Lee dies for that. But I never tighten the die or top punch. With the die I snug it up but then back it off a half a turn. With nose punch I slop the stem up with lube which holds it place. This leaves everything floating. Since nothing is tight both parts seem to self align. Works pretty good.


Robert Homan

Attached Files

Shopdog posted this 24 April 2020

"One" way(there's several ways to go about this) is to turn a top punch into a "range rod". Basically,you turn a top punch, - a cpl "tenths" (.0001's) under the sizer ID and pull the handle. You'll "see" pretty quick what's what.

I made a top punch a month ago for a Lee 452-190 that bypasses the nose of the bullet,and registers on the SWC,or outer edge of the top driving band. The logic,and it does work.... is that I was controlling the amt of engraving during chambering.

Matching seater stem,to set OAL; It works peachy. When doing OAL setting,I was using a plunk test on the barrel. Get it so that it's about .001"...."long",and requires a smidge of finger pressure to seat. As if there isn't enough going on during the cycle of a 1911? It works and shows up in paper,Mr Ripley(believe it or not).

Back to range rods; I didn't realize when making this top punch that it was too long when trying to size in a 450. So,back to the lathe and turned down the OD of the bttm portion of the TP to a cpl tenths less than the ID of the H die.

With a Proto 3/8" torque wrench in a welded socket on the 450 handle,this setup gives you two options. One is use a torque setting (clicker type wrench),the other is setting by "depth"(no torque wrench),letting the shoulder on the outside of top punch act as a "stop" against top of H die. One critical aspect here,and this applies to ANY size bullet..... is that you match the seater stem to the top punch. They need to be a matched set.

And yes,have made a bunch of bore rider style bullet,nose punches that effectively do the same. These are sizing base first and usually are part of a nose bump. Which I've come to rely on a beam style torque wrench for. Was bumping some RCBS 22's this morning. I can't really give you #'s on the wrench because the ratio depends on where the TW is attached to the handle.

It's easy though. You're going to feel EXACTLY where the nose yields. Write it down,take measurements,write that down. Think about what you want,and try to "guess" what the torque pressure "should" be, vs just keep trying/measuring. Yes the latter works but I feel you aren't getting the full benefit until you can actually start to predict the "upset" beforehand. Then,you'll appreciate say 150" of pressure vs 200".

A bore rider has an advantage on a test plate;

If you don't gum up a sized/bumped bullet with lube it's an EASY visual rolling it on a test plate. You'll not only see the effects of the fitted top punch clearly,you "should" see some out of roundness. At this point,of inspection you can also start playing with some other features,mostly based on how "deep" you run the bullets down into the H die. Most of my sizing is only on the GC end,and MAYBE halfway up the lowest drive band.

This last part is also critical during inspection and dialing in the alignment. Hard to put into words but here goes"

If you have a reasonably round bullet coming out of the mould. You should be able to calc,.... how out of round by looking at the "line" where the sizing stops halfway up that lowest drive band. If it isn't perfect,.... it's at an angle,more on one side.... then you have a type of hysteria somewhere in the system.

At this point you should be wondering about that factory H die.... along with some other,should be obvious places. Each "system" is going to be a case in itself.... sure,I could say to look "here". But that doesn't hold water from a manufacturing standpoint. It's up to the individual to locate where the problem is. Sorry for the novel.

Attached Files

  • Liked by
  • RicinYakima
  • Bud Hyett
admiral posted this 25 April 2020

I have a RCBS LAM2 that is used strictly for nose first sizing. I bought it used and melted out the lube that was inside and removed the bullet eject rod and adjuster screw. I long ago noticed the top punch alignment problems that sometimes popped up. Another plus is never having to buy top punches.

Attached Files

John Alexander posted this 25 April 2020

I have heard RCBS's brag of cutting both holes in the casting with one operation for precision. I have always wondered why bother if you are not going to tighten up the tolerance between the top punches and the ram. The slop is nowhere near .001" on the ones I have ever had.  Great precision in one place destroyed in another.

I size nose first with Lee dies.  I leave the die loose to self align and keep the top of the ram greased.

 Pat Iffland had a short Fouling Shot article (maybe 15 years ago) on the difference between base first sizing and nose sizing that showed the visible difference on the bullet.


Attached Files

OU812 posted this 25 April 2020

I only use the rcbs to lube rifle bullets after they are sized in the Lee. I use an over size die/pin so bullet is not sized and less resistance. Using lube that is too cold or hard adds more resistance and will distort or bump bullet larger. Stem inside die must fit snug or lube will leak out under pressure.

I once accidentally bumped bullets larger by simply lubing them only. Bullet would not chamber afterwards.

Attached Files

  • Liked by
  • John Alexander
  • Bud Hyett
4and1 posted this 26 April 2020

When I was collecting equipment to start sizing cast bullets, I bought a used Lyman 45. When I check the top punch to sizing die, I could see the misalignment with my eye, no measuring needed. Plan B.

Using my RCBS Junior reloading press, I made a sizing die setup that uses a Lyman or RCBS sizing die (already hardened), an ejector rod and setup on the press, and a "top punch" to fit the shell holder. The body was a barrel drop (what else do you do with these things) that had a bore already there, so the OD was turned between centers and threaded. One end was bored to accept the sizing die, and the other was made to act as a stop and also to eject the bullet. The punch was made to fit in the press ram, loosely and fits the bullet nose. Gas checks are installed separately on another die with an arbor press, then the bullet is sized base first into the sizing die, against the stop. The direction of sizing keeps the GC in the seating position and again seats the GC at the top of the stroke when is hits the stop. The bullet is ejected pushing on the base. If there is any misalignment, it self-centers at the shell holder/top punch that is a loose fit.

I powder coat, so I don't need lubing. But I do lightly lube the bullet before sizing on a case lube pad.

Attached Files

Ross Smith posted this 28 April 2020

I too can see visual evidence of mis-alignment in my rcbs II. I can see rub marks on any bullet i size always on the same side. Rotate the bullet 180 and it will rub the un-rubbed side from the first pass. Hmmmm.

How do you'all lube and GC, mostly how do you lube, with nose first dies? I've used lee and NOE push thru's but have had some problems with gc's and lubing. Pan lube?

Attached Files

  • Liked by
  • Bud Hyett
Bud Hyett posted this 28 April 2020

I've never had consistent results with pan lubing. the lubricant does not stick in the bullet grooves long enough to fire the cartridge, Soft lube or hard lube, sticking in the refrigerator or freezer to harden, the lube fails out of the grooves as I load the cartridge or push the bullet in for breech-seating.. My experience with pan lubrication does not parallel the enthusiastic experience of others

After reading the conversations above, I am trying:

  • Seat the gascheck gently using SAECO lubrisizer gascheck feature to assure alignment and full seat
  • Be careful not to press too hard to avoid bumping the nose diameter up.
  • Size nose first in NOE sizing setup
  • Seat the bullet in either the SAECO ) (.310) or RCBS (.311) sizer to lubricate and finalize the gascheck seating,
  • These lubrisizers have dies .001 oversize to assure the bullet does not get touched.

With both Alice and I shooting Military and she shooting Production, we need a semi-production setup for the volume of match and practice ammunition. Second, third and fourth Saturdays, fourth Thursday are match days here in the Pacific Northwest. And it will possibly be June at the earliest when matches begin.This year, we will need more practice ammunition once the range is opened up. 



Farm boy from Illinois, living in the magical Pacific Northwest

Attached Files