How to minimize runout?

[rosenbaumtravis]

After sizing, my cases have very minimal runout. However, when I seat my barnes TSX 308 bullets they end up with excessive runout. Im using a forster seating die. Please share your tips and tricks for limiting runout.

[fguffey]

I'm using a Forster seating die.

I do not have a Forster seating die. Then there is that part about run out, where is the run out indicated? My seating dies do not have case body support, there is a press designed for seating bullets with a hydraulic gage. Some have discovered it can require 45 pounds to seat bullets. I am for that, I want all the bullet hold I can get.

I have seating dies that go back to when they were sold as 'UNIVERSAL', that would be one body die with a lot of small parts. I thought the advantage to the die was the alignment between the case neck and bullet. Same for Competition seating dies.

I made a seater without a die body, seating bullets with it is 'almost' effortless.

F. Guffey

[bsumoba]

what kind of die do you have? FL bushing die, FL standard die, Neck Sizing Die?

How are you measuring your runout and what tool? Hornady, 21st Century Tool and measuring off the body or off the case head?

The way I have limited runout is to make sure the bushing is floating just a little bit (assuming a bushing die).

Need to know the answers to the questions in order for us to help a little more.

[Whiterabbit]

Also what kind of runout do you have? what tool are you using to measure runout, and the procedure you use to run the tool? My standards for runout on a 100 yard gun are "do they chamber". If this is your excess runout, my advice and opinions are relevant and important.

If you have .002 runout and consider that excessive, I'm not going to be able to help you, and will let the benchrest guys do the heavy lifting.

(cause there is no reason to spend $100 fixing something if your standards don't require that tolerance)

[bsumoba]

Also what kind of runout do you have? what tool are you using to measure runout, and the procedure you use to run the tool? My standards for runout on a 100 yard gun are "do they chamber". If this is your excess runout, my advice and opinions are relevant and important.

If you have .002 runout and consider that excessive, I'm not going to be able to help you, and will let the benchrest guys do the heavy lifting.

(cause there is no reason to spend $100 fixing something if your standards don't require that tolerance)

There have been multiple tests by world class shooters like Jerry Tierney, Bryan Litz and the likes, with rounds with "excessive" runout and in my game, F-Class (and some would argue in LR benchrest also), it does not make a whole lot of difference on paper. Shooting conditions are more likely to effect the impact of the bullet on target than a couple thousandths of runout.

That being said, my dies are set and my reloading process gives me less than 0.0015" of runout typically. If I get one that is around say 0.003", I don't sweat it. I only have 0.0005" of bullet clearance (that is 0.00025" per side) in my freebore, so chances are, the round will be sort of centering itself anyways when chambered. I also jump all my rounds so it might help correct any amount of runout as it starts into the lands.

['ol shooter]

When I seat a bullet, I start it into the case a little, release, and finish. The release after the initial push seems to be working for me, since my ammo rolls pretty straight.

[rosenbaumtravis]

I'm using the Forster Ultra Micrometer Seater Die. It is very similar to the Redding Competition Seating Die. It supports the case as you are seating the bullet. I bought it in hopes to solve my issue with run-out.

I'm using the RCBS Case Master to measure run-out. Most bullets have between .006 to .009 run-out. The tool supports the case on the body using a v-block. I'm measuring close to the bullet ogive when i spin it on my case run-out gauge.

My case necks have less than .001 run-out, so I think my problem is with seating. I have tried to "float" my die using an o-ring, but it didn't help. I only have this problem with Barnes tsx bullets. SMK's seat just fine. I do notice the Barnes bullets don't seat as smoothly as others. They hang slightly on the grooves cut into the bullet. I have tried using a VLD chamfering tool to put a good chamfer on the case mouth, but it didn't help.

Could this be caused by too much neck tension? If so, what is ideal and how do I change the neck tension? I have redding neck, redding full length, dillon carbide full length, and rcbs 308 sizing dies. All this is being done on a RCBS Rock Chucker.

[bsumoba]

I'm using the Forster Ultra Micrometer Seater Die. It is very similar to the Redding Competition Seating Die. It supports the case as you are seating the bullet. I bought it in hopes to solve my issue with run-out.

I'm using the RCBS Case Master to measure run-out. Most bullets have between .006 to .009 run-out. The tool supports the case on the body using a v-block. I'm measuring close to the bullet ogive when i spin it on my case run-out gauge.

My case necks have less than .001 run-out, so I think my problem is with seating. I have tried to "float" my die using an o-ring, but it didn't help. I only have this problem with Barnes tsx bullets. SMK's seat just fine. I do notice the Barnes bullets don't seat as smoothly as others. They hang slightly on the grooves cut into the bullet. I have tried using a VLD chamfering tool to put a good chamfer on the case mouth, but it didn't help.

Could this be caused by too much neck tension? If so, what is ideal and how do I change the neck tension? I have redding neck, redding full length, dillon carbide full length, and rcbs 308 sizing dies. All this is being done on a RCBS Rock Chucker.

If this happens only on a particular bullet, maybe the bullet is out of round or the "hanging" up of the bullet is canting the bullet and thus, your runout???

To measure neck tension, measure the diameter of an unloaded piece of brass at the neck, about 1/3 down from the top of the neck. Then, load a round and then measure the neck at the same spot with the loaded round. The difference is your neck tension.

[JMP]

1. Straight necks, including uniform neck thickness
2. Straight projectiles
3. Good seating dies

Many people think that the reason to get good dies is to have the micrometer on top. That's generally just a side benefit. Really, what makes a good die is one that guides the projectile in straight. They generally have a spring-loaded housing that fits the cartridge.

Of course, you need to start with a well-sized cartridge that is symmetric. Generally, people will pay a bit more for good uniform brass and/or they will turn their necks. Thus, other parts of the preparation also matter.

[LynnJr]

Frank
I don't know what kind of seating die you are using but if removing the body of the die made it easier to seat your bullets you are doing something terribly wrong. The body of a seating die affecting how easy it is to seat a bullet screams trouble.

Travis
When you full length size a case you are making the outside dimensions uniform so I am not surprised they spin true.
When you then seat a bullet you take any neck inconsistency and move it to the outside of the case. Naturally you have a thicker side and a thinner side so the brass expands unevenly as you seat the bullet.
The cure is neck turning your brass properly.
Are you already turning your necks?
The o-ring trick rarely works because the brass can already wiggle all it wants to inside the shellholder.
As you spin your loaded rounds make sure the case is not moving laterally. The shape of the bullets ogive tries to push the bullet towards the cases base.
The number one problem with lathe turned bullets is bent ogives from the machining process so check the runout in several locations.

[micro911]

I push up 1/2 way and rotate the cartridge case 180 degrees and finish. It gives me a good loads. For 200-300 yards, I do not care much about the runout. For 600 yard ammo, I do.

[rosenbaumtravis]

Frank
I don't know what kind of seating die you are using but if removing the body of the die made it easier to seat your bullets you are doing something terribly wrong. The body of a seating die affecting how easy it is to seat a bullet screams trouble.

Travis
When you full length size a case you are making the outside dimensions uniform so I am not surprised they spin true.
When you then seat a bullet you take any neck inconsistency and move it to the outside of the case. Naturally you have a thicker side and a thinner side so the brass expands unevenly as you seat the bullet.
The cure is neck turning your brass properly.
Are you already turning your necks?
The o-ring trick rarely works because the brass can already wiggle all it wants to inside the shellholder.
As you spin your loaded rounds make sure the case is not moving laterally. The shape of the bullets ogive tries to push the bullet towards the cases base.
The number one problem with lathe turned bullets is bent ogives from the machining process so check the runout in several locations.

I have tried turning the necks, but got very poor results. I used the rcbs neck turner that mounts on my lathe type trimmer. I will invest in a decent neck turner. Any recomendations on a good neck turner?

[fguffey]

I made a seater without a die body, seating bullets with it is 'almost' effortless.

A seating die does not have case body support, then there is the discovery by reloaders the amount of effort required to seat a bullet can be measured with a small hydronic press. The press does not measure tension, I do not have to get used to that ideal because I have never used tensions when seating bullets.

I made a bullet seater without a die body.


rosenbaumtravis, you said the cases do not have run-our before seating the bullet. You have no ideal how much pressure is required to seat the bullet and you do not know if the run out is caused misalignment between the case neck and bullet when seating.

F. Guffey

[fguffey]

rosenbaumtravis, Every case? As in every case is removed from the sizing die with little to no run-out but every case has run-out after seating the bullet?

Does that mean every case neck must be turned?

F. Guffey

[rosenbaumtravis]

rosenbaumtravis, Every case? As in every case is removed from the sizing die with little to no run-out but every case has run-out after seating the bullet?

Does that mean every case neck must be turned?

F. Guffey

Yes. Every TSX 130 gr 308 bullet i seat has more run out than my smk loads. Its only an issue with this bullet.

I will try neck turning to reduce the neck tension on few cases and check for runout.

Tried some more tonight and noticed that small amounts of copper is being stripped from the bullet when i seat them. More than other bullets.