Erratic concentricity issues

[SDHNTR]

I just bought a pile of .270 reloading equipment off a friend who's dad died and he isn't a reloader. A bunch of new Win brass, standard Redding dies and a couple boxes of Barnes TTSX. I've reloaded and shot about 50 rounds worth so far, over a few sessions. About 1 in 8 or 10 rounds has terrible concentricity. Roughly .012 - .015+ runout. All the rest are an acceptable, sub .005"tir. This has happened over several reloading sessions/batches. I've measured the brass at the neck before and after sizing, no issues. It's straight, .001-.002" tir. Used new and once fired brass, same. It's when I measure a loaded round at the ogive that I see the issues. The really bad ones you can even see the runout visually. So do I look to my seating die? (even though the majority of the rounds are fine?) And if so, what do I look for? Or did I just get a wonky lot of Barnes bullets?

 

[DaveCB]

From your description it sounds like the seater die is causing the problem. You would think there would be more pieces with poor run out.
I would anneal the necks on the brass and use plenty of lube on the inside when resizing, FL resize is what I do. clean the shell holder if it has a buildup in the groove.
Should be a #1 A #2 for some of the other brand Dies.
I would make sure the seating die was clean and the bullet fit to the seater was good.
If some of the brass was shot in a semi auto the rim could be bent or have a wowee from the extractor. that would cause the brass to set off center in the shell holder.

 

[SDHNTR]

From your description it sounds like the seater die is causing the problem. You would think there would be more pieces with poor run out.
I would anneal the necks on the brass and use plenty of lube on the inside when resizing, FL resize is what I do. clean the shell holder if it has a buildup in the groove.
Should be a #1 A #2 for some of the other brand Dies.
I would make sure the seating die was clean and the bullet fit to the seater was good.
If some of the brass was shot in a semi auto the rim could be bent or have a wowee from the extractor. that would cause the brass to set off center in the shell holder.

I do anneal and use neck lube. Will clean die and shell holder and see if that helps but I also did that before I started. Bolt action only.

 

[TaperPin]

Do you chamfer the inside of the case neck with a very low drag (vld) reamer?

Barnes is soft enough some bullet metal can be shaved during seating with a normal reamer.

 

[mddat]

I’d bet it’s the seating die, do you have any other 270 brass you could try and see if it still happens? Also have you shot any groups of the good vs bad to see if there’s any real world difference?

 

[TaperPin]

You could mark the case before seating the bullet and oriented the case the same way - if the concentricity is always out in the same direction you might have a wonky seating stem or die. Redding dies are usually pretty reliable.

 

[SDHNTR]

Do you chamfer the inside of the case neck with a very low drag (vld) reamer?

Barnes is soft enough some bullet metal can be shaved during seating with a normal reamer.

Yes I do.

 

[SDHNTR]

I’d bet it’s the seating die, do you have any other 270 brass you could try and see if it still happens? Also have you shot any groups of the good vs bad to see if there’s any real world difference?

I haven’t settled on a load yet so haven’t done any real accuracy testing.

 

[Wrench]

How are you measuring runout on fired cases?....outside with an indicator? You could have issues with the brass thickness which would take a collet die, reamer or ID indicator to verify.

Have you tried seating by starting the bullet and then rotating 90* a couple times during the push? Have you tried lubing the neck with graphite or mica to see if it helps?

On my rcbs press it takes a lot of stars to align to break into the
.003" or better area. If I use my forster coax...it's simply more consistent.

 

[gbflyer]

I used to make myself crazy over this. I don’t anymore. I sorted out 10 that were over .005, 10 that were less than .005. Measured at the ogive. There was no appreciable difference in the groups.

 

[SDHNTR]

How are you measuring runout on fired cases?....outside with an indicator? You could have issues with the brass thickness which would take a collet die, reamer or ID indicator to verify.

Have you tried seating by starting the bullet and then rotating 90* a couple times during the push? Have you tried lubing the neck with graphite or mica to see if it helps?

On my rcbs press it takes a lot of stars to align to break into the
.003" or better area. If I use my forster coax...it's simply more consistent.

Yes measuring outside of necks. Fired cases are less than a thou. Sized are 1 or 2 thou. This doesn’t happen until after seating and measuring the ogive on the bullet.

Yes I rotate 90 during seating. Could be an interior of neck brass thickness issue but the expander should clear up most of that.

I’d gladly take .003”- .006”. I don’t sweat that little bit at all. This is 2-3x that when it occurs.

 

[SDHNTR]

I used to make myself crazy over this. I don’t anymore. I sorted out 10 that were over .005, 10 that were less than .005. Measured at the ogive. There was no appreciable difference in the groups.

Agreed. But Big difference between .005 and .015”.

 

[35WhelenAI]

It has been mentioned above, despite run-out, how do they shoot? The case expands against the chamber wall and pretty much squares things up as the bullet begins two feet of travel down the bore. That run out isn't much of a thing in a mass produced gun if it chambers smoothly and has no bolt closure issues.

Is there one every now and then that seems to hang up and have a bit of an issue with initial entry into the case mouth? Could cause a bit of collapse that shows up as run-out. Using a VLD chamfer is a good idea with Barnes, been doing that for a long time and keeps the bullets from being shaved.

 

[DaveCB]

Well, I had a rifle 243AI. Lapua brass. Was using it for 1000yd bench rest. I had purchased a set of dies from Redding run out was excessive. FL and Neck dies I sent the dies to Redding along with several fired cases. About a week later they returned the dies and basically said there was nothing wrong with the dies. So, I pulled my hair out trying to figure out why I had all that run out. .003 to.006, Thats what I considered excessive for a set of dies that cost $200 in the 1990s. So last thing I did that fixed the problem for me was I removed the bullet expander from the die. I had a 243 lee collet die. I ran the brass through the collet die with the mandrel I had ..003 bullet squeeze on my loader ammo and .002 to .0025 run out.

 

[SDHNTR]

Well, I had a rifle 243AI. Lapua brass. Was using it for 1000yd bench rest. I had purchased a set of dies from Redding run out was excessive. FL and Neck dies I sent the dies to Redding along with several fired cases. About a week later they returned the dies and basically said there was nothing wrong with the dies. So, I pulled my hair out trying to figure out why I had all that run out. .003 to.006, Thats what I considered excessive for a set of dies that cost $200 in the 1990s. So last thing I did that fixed the problem for me was I removed the bullet expander from the die. I had a 243 lee collet die. I ran the brass through the collet die with the mandrel I had ..003 bullet squeeze on my loader ammo and .002 to .0025 run out.

It’s not a sizing issue. Brass comes out of the sizing die with minimal tir.

 

[SDHNTR]

It has been mentioned above, despite run-out, how do they shoot? The case expands against the chamber wall and pretty much squares things up as the bullet begins two feet of travel down the bore. That run out isn't much of a thing in a mass produced gun if it chambers smoothly and has no bolt closure issues.

Is there one every now and then that seems to hang up and have a bit of an issue with initial entry into the case mouth? Could cause a bit of collapse that shows up as run-out. Using a VLD chamfer is a good idea with Barnes, been doing that for a long time and keeps the bullets from being shaved.

I haven’t really focused on shooting groups but I can see there’s potential with this powder and bullet.

I don’t feel anything out of the ordinary when seating bullets. Feels smooth.

 

[SDHNTR]

You know what, I think I need a VLD seating stem. I just took the seating die apart to clean it and thought I might as well drop a 130 TTSX into the seating stem. Sure enough, the tip bottoms out. I then took apart another die with a VLD stem and it holds the bullet MUCH better. I may have just found my own problem. I wouldn’t have thought that bullet would need it.

 

[35WhelenAI]

Good catch on the seating stem.

Now do it with 10 cartridges and the different stem and see what happens.

 

[Vern400]

Good catch! I use RCBS competition dies that help start the bullet straight. But if the seater stem actually pushes on the tip of the bullet, all bets are off. The meplat is where all the run out goes in bullet manufacturing. I guess the farther back on the bullet the force is applied the better because it has a better bigger footprint to give everything straight while the force is applied to seat the bullet. Many pistol die sets have multiple seating stems for different bullet shapes.

 

[Wrench]

It’s not a sizing issue. Brass comes out of the sizing die with minimal tir.

Measure the internal and external after you pull the sizer through. My experience mirrors the above. I will take a collet every time. They don't rely on the brass thickness, die alignment nor press runout....they just press to a standard. The expander is at the mercy of the brass resistance.