Run out...WTF?

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maynard

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Ok, I normally don't check run out. I am using annealed Lapua Brass, 2156 Sierra Palma bullets, Redding Big Boss press, Redding Type "S" resizing dies and a Redding Competition seater. The only thing that I have changed over the years in this set up is the seating depth for different bullets. When everything as set up the first time, I did check the run out and it was never over .001". Now I am getting up to .010" TIR on some loaded rounds. Some rounds are .002"-.004" TIR

The resized case are clocked at .001" or less, the problem is when I seat the bullet. The neck run out does not change but the bullet is not being seated straight. With the indicator point about .200" from the end of the bullet is where I am getting this wobble. I have tried seating the bullet in 3 different steps rotating the round about 1/3 of a turn each time. I have tried 3 different shell holders thinking this might be the problem, not. The dies are clean and move freely. I have also tried some RCBS seating dies and even found an old Lee seating die on the bench. The Lee die had the least amount of run out. I can get these to run true on the concentricity gauge by pushing the bullets down with my thumb, but I have about 600 more round to go.

I can only hope I don't have this same problem when I start on my .223 loads.

I am not sure if I have a die problem or a press problem. I guess we will have to wait and see what happens when I change over to the .223.
 
You're measuring .2" from the tip?

Runout is measured just in front of the case neck. Below the ogive. Measure there and see what it is.

I don't get these "cartridge straightening" devices. I can't imagine bending necks and messing with tension helps more than it hurts, but I've never tested it. I mean, you can work bullets loose by bending them against the neck, so it doesn't seem like anything I'd want to do on purpose.

Are you using a gauge like this or that Hornady contraption?

https://x-reload.com/rcbs-case-master-gauging-tool.html

I'm sure you did, but since it's not mentioned, I gotta ask - have you chamfered your brass? Even without trimming it can lose the chamfer after tumbling.

I've never been able to detect any change in runout by rotating the cartridge while seating. Two, three, four, six times - it all comes out the same as without rotating.

If your necks have runout that low and are chamfered, it seems it is indeed narrowed down to the seating process, but I'd want to check with a new piece of brass or two just for confirmation.
 
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maynard said:
Ok, I normally don't check run out. I am using annealed Lapua Brass, 2156 Sierra Palma bullets, Redding Big Boss press, Redding Type "S" resizing dies and a Redding Competition seater. The only thing that I have changed over the years in this set up is the seating depth for different bullets. When everything as set up the first time, I did check the run out and it was never over .001". Now I am getting up to .010" TIR on some loaded rounds. Some rounds are .002"-.004" TIR

The resized case are clocked at .001" or less, the problem is when I seat the bullet. The neck run out does not change but the bullet is not being seated straight. With the indicator point about .200" from the end of the bullet is where I am getting this wobble. I have tried seating the bullet in 3 different steps rotating the round about 1/3 of a turn each time. I have tried 3 different shell holders thinking this might be the problem, not. The dies are clean and move freely. I have also tried some RCBS seating dies and even found an old Lee seating die on the bench. The Lee die had the least amount of run out. I can get these to run true on the concentricity gauge by pushing the bullets down with my thumb, but I have about 600 more round to go.

I can only hope I don't have this same problem when I start on my .223 loads.

I am not sure if I have a die problem or a press problem. I guess we will have to wait and see what happens when I change over to the .223.
Click to expand...

Hi Maynard

You have very good equipment and materials and it sounds like you are an advanced reloader.

I have a question for you ... Are you creating compressed loads? If you are, or loads with a high neck tension, it is possible, if not likely, that you have cracked or flared out your floating seating stem in the Redding Competition Seating die. I have this same die and I am very careful not to compress loads with it. I have read this on the Internet a few times about cracked Redding seating stems in their competition seating dies. Redding ships these dies with a warning/disclaimer not to use them for compressed loads.

Another question for you ... What are you using to measure concentricity? I use the Hornady Concentricity checker and it works very well for measuring bullet run out. Occasionally I use the correction screw knob to make concentricity corrections for rounds that are over .002". I find it works great and it doesn't need much torque. I have been doing it for years and it does not loosen the neck tension on the bullet if a person is reasonable about it. I have never noticed any ammunition accuracy issues using this tool.

I hope this post helps you. I know bullet run out is frustrating when you are using high quality dies that are supposed to reduce it.
 
Hi Maynard,

A cracked seating stem will definitely affect concentricity in a big way. I would recommend that you check it by taking the Redding Competition seating die apart, not difficult to do, and check that floating seating stem. It is a somewhat delicate piece of kit ... it is an awesome die, some say the best, but this is its Achilles heal.
 
Hi Maynard,

I had one more thought. The length of bullet and the tightness of the brass neck may present a decent amount of resistance to that delicate steam. I am not sure what caliber you are experiencing this with. I didn't catch it. To reduce the bullet seating pressure I use Redding graphite powder for the inside of the case neck or the shank of the bullet (preferred). I find it helps with a smoother, easier bullet insertion.
 
Maynard

Question, are you wet tumbling your cases with stainless steel media?

If the case mouth is peened it could effect bullet runout but not show up on case neck runout. I have to trim and deburr my cases every time I wet tumble to clean up the case mouths.
 
bigedp51 said:
Maynard

Question, are you wet tumbling your cases with stainless steel media?

If the case mouth is peened it could effect bullet runout but not show up on case neck runout. I have to trim and deburr my cases every time I wet tumble to clean up the case mouths.
Click to expand...

Good point. 100% agree. I do the same for the same reason
 
The bullet only runs out near the tip, just in front of the case mouth it is only .001" or less. The problem is near the end of the loaded round where it is not running concentric. If the bullet isn't straight in the case to begin with, chances of smacking bulls and v's at 300 to 1000 yards seems slim.
Cases are not wet tumbled and are only have .002" neck tension. The bullet almost seats with the weight of the press handle.
 
maynard said:
The bullet only runs out near the tip, just in front of the case mouth it is only .001" or less. The problem is near the end of the loaded round where it is not running concentric. If the bullet isn't straight in the case to begin with, chances of smacking bulls and v's at 300 to 1000 yards seems slim.
Cases are not wet tumbled and are only have .002" neck tension. The bullet almost seats with the weight of the press handle.
Click to expand...

ok ... well take one of these bullets and put it in a hand drill and spin it as fast as that drill is able ... if the tip doesn't wobble then your inside case neck bore is not aligned with the case body ... which means that the sizing die has done something to your brass
 
Carbon12 said:
ok ... well take one of these bullets and put it in a hand drill and spin it as fast as that drill is able ... if the tip doesn't wobble then your inside case neck bore is not aligned with the case body ... which means that the sizing die has done something to your brass
Click to expand...

Try with different brass are resize the brass in question with another sizing die from the one you used ... maybe your lock ring has moved ...
 
Did you take the die apart and see how the bullet seater(whatever its called) looks? I've turned, polished and tweaked the bullet seater of dies a few times. They seem pretty sort and real thin, sometimes they get damaged.
 
maynard said:
The bullet only runs out near the tip, just in front of the case mouth it is only .001" or less. The problem is near the end of the loaded round where it is not running concentric. If the bullet isn't straight in the case to begin with, chances of smacking bulls and v's at 300 to 1000 yards seems slim.
Cases are not wet tumbled and are only have .002" neck tension. The bullet almost seats with the weight of the press handle.
Click to expand...

If you've got 1 thou runout on the bearing surface in front of the case neck, you don't have an issue. You have very low runout.

Just for giggles though, I measured a few of my rounds for runout at the tip, and they were 4-5k over runout on the bearing surface. So 10k at the tip seems high, but I'd want to measure what it was at the ogive.

I don't know of any authoritative source that I've read that suggests measuring it at the tip, the convention is to measure on the bearing surface.

Until you measure at the ogive, we're all talking apples and oranges.
 
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