Home Forums Hunting & Shooting Ask The Gunwriters Press contributing to runout?

In the quest to track-down & snuff out my runout issues, I've come across some "innanet wisdom" that says a loose/wiggling ram, or shell holder secured by a poorly made retaining clip, can cause runout. The former was to be, "cured" by a new press, and the latter possibly fixed by discarding the clip & employing a rubber band or o-ring.

Can this be accurate?

Or, if so, would it still be far less of a contributing factor than die setup?

FC

It might help if you specified the press you are currently using and give its exact history.
How old?
Bought new or used?
Thrown down stairs repeatedly? Used to pound fenceposts?


Also, if it would help to get this all figured out, you are welcome to visit the Shamanic Secret Underground Reloading Cave and try your dies on my RCBS RockChucker. I could also loan you a die set if need be. If so, let me know, and I'll start briefing Ed, the Guard.

How much run out are you getting?
As a side note, I have seen the locking rings on a set of dies I have cause runout, The ring was not faced off square to the threads and when you tighten it down in the press it would push all the slop in the thread to one side causing the die to cock. This was finger tight in the press but I went with another locking ring and all was good. To prove it was the ring, I marked the cases so I could index them and sized them and check the runout against the index mark. Then I took a piece of paper and put a small piece between the press and locking ring on the low side. I resized another marked case and my runout was cut so I added a second piece of paper shim and tried it again, my runout was gone.

Loose isn’t bad - it’s called floating, and it’s good because it lets the rounds center themselves.

I float my dies and pin them on my Dillon presses, and on my RCBS rock chucker I use a rubber band in ram instead a spring loaded shell holder, and I float the die at the top with a pin, my Co-Axial press floats the top die by design.

Lee, from Breech Lock Challenger Kit, NIB, received 12/2015. Carried from packaging box to reloading bench on a 2.21' thick bed of thrice-fluffed Spotted Owl feathers. Held between 69 and 72 degrees F ever since, maybe 2K-ish rounds loaded since removed from box.





That's probably not a bad idea. Hold the Scoresby, please...

FC

Hmmmm. Were the spotted owl feathers gathered from a male or female?

I think I might have something laying about we can use for a social lubricant besides Scoresby. I'll go down and check the solvent shelf.


(Nothing I like better than having one of my best buddies come over and get all likkered up with me, and then we start reloadin'! YeeeHaw!)

I don't know the answer but my solution was to float everything that could be. I use the Lee lock rings or any of the better split lock rings and an O ring. Seems to be working for me. My A-2 press is of indeterminate age and load count but I think it is older than I am so it is ancient. The ram has some play in it from wear but it doesn't seem to be a problem. Only on my little Lee C press that I use as a portable has springing been a concern. I just use it for bullet seating with moderate neck tension and no issues, I won't use it for any major operations, that's what the other other presses are for.

On any of the better presses I don't think it is an issue if everything is set up square to begin with. SOP is to replace any of the solid screw lock rings or at the least take the lock screw out and drop a #7&1/2 lead shot down the hole and put the screw over this. This locks the die with less torque or tendency to get out of alignment.

A wee dram of single malt seems to help with alignment too, but this only works initially, too much lubricant and things start to get out of alignment again.

Could be the press,but I would try adjusting your expander rod/plug. Turning 1/8 th turn at a time and sizing a case at each turn and check run out. Or size case without the expander plug.Then go back and expand with a down stroke. Brass that needs annealing will get pulled more so than those not.

I run my die down until it contacts the shell pale and then tighten the lock ring with ram up against the die.Some times I do not tighten the locking ring and let the case center itself.I am not sure that helps though. Biggest problem for me has always been the expander plug

Some of the old lock rings that used set screws that impinged on the die body threads were bad for cocking the lock ring, see if your run out reduces by fully floating the die, lock ring backed off. Long term, if that is a cause, buy Forster clamp style lock rings.

An easy way to test this might be to loosen the set screw and back a second lock ring on in the double nut/jam nut style of keeping the ring from moving...

I've had screwed up dies/lock rings as discussed. I've had the die hole in an RCBS Rock Chucker off center from the ram. Everything can and has been screwed up, nothing is fallible

THIS^^^^!!!!

And the idea of allowing a little bit of "float" that in turn allows the brass to "follow" into the die is a tough concept for many.

No ram and die hole in the press will be precisely aligned, and no die threads, or interior, are precisely align with the ram or die hole in the press. There can be stacked tolerances that really get things out of alignment, but by the same token those same stacked tolerances can end up with almost precise alignment.

Usually it's not something that is going to significantly contribute towards or against accurate ammo.

One of the best ways I've ever seen to check ram / die alignment is with a press mounted wad punch. Shell holders tend to be sloppy for hull / die self centering but sloppy doesn't seem to happen when you insert the punch in the ram and die in the top of the press you will find out rfn if they really are in good alignment. Make sure the shell holder groove in the top of the ram is clean with no crud at all and clean the base of the shareholder as well as the rim groove. Mb

I would think that if you are getting runout on all your ammo with a variety of dies, it has something to do with the press. If you are only getting runout with your loads in one cartridge, it has something to do with the dies.
Does every cartridge you load for have the same runout issues?

Joe,

I had a runout issue with my Lee Classic Cast press. I emailed Lee about it and they requested that I send it in. They found the piece that held the shell holder out of spec and replaced it. My loads have been fine since.

Yeah, it's across multiple cartridges. Mostly RCBS dies, with 1 set of Lee thrown in there. I usually have to fix about 75% of the loaded cartridges on the TruAngle tool.

The last batch was 95% needing to be fixed, with some over .012 runout. I have a hard time believing that I suck that badly: I'd like to believe there's another culprit besides myself.




Thanks for that. I suppose it's worth contacting them. Details to follow.


FC

One thing to try is to check run out at each step to see if you can isolate where it is happening. Sometimes it is cumulative and each step increases the run out but you won't know until you check. Another thing is bad brass, if case necks are thicker on one side then the body will be too, these size and spring back unequally and will induce run out. Like most things it will be a process of elimination to find and fix the causes.

Mathman made a similar post a few weeks ago, but I couldn't find it yesterday.

You are correct. Want to know where TIR is introduced, check it at every step in your process.

Good post.

The old school way to float dies is with a o ring under the lock ring and one under the seating stem, so that it aligns itself. It will certainly work, or buy a co-ax press.

I did this and it helped. Also used those Hornady split lock rings.