6.5 Creedmoor - poor neck tension?

[jaygorski]

I'm not sure I 100% trust my numbers, but I'm getting readings of around 14 thou. 14*2+264=292-2=290. So the numbers support the .290 bushing, but my real world experiences are telling me that it's not enough. My 0.289 bushing is arriving tomorrow; I'll give it a try.

Unfortunately I kinda shot myself in the foot by blindly trusting numbers given to me by the guy that got me into this stuff, and sizing everything before realizing there's an issue.

338 dude, I'm curious about this mandrel method. Do you simply use a super small bushing, then open it back up with your mandrel? Would you do it again if you were to start over again?

Trouble is, if you measure all your brass some will be less than .014", some of my Starline measures 135"-138", my 289 bushing seems to work good for the entire lot.

 

[jaygorski]

Some of my tools for the 6.5, my son's rifle.

 

[vulrath]

The Hornady 0.289 bushing definitely did the trick. I haven't tried the.288 bushing, but I don't know that I need to. Bullets seat properly and don't move when I push them.

I got the steel bushings because they were available. I might get the TiN bushings down the road, but for now I've got these.

 

[Hohn]

Calipers really aren't the best for measuring neck thickness it's best to use a ball micrometer.

Measuring wall thickness is generally a less precise way to go even with the one tool that does it properly (a ball mic). A better approach is to measure OD at several points with a mandrel or some known diameter hard object inserted. There’s a reason your turning setups use a mandrel. Your measuring would likewise benefit. There are several things of known diameter you can stick into the neck to use as a gauge reference: expander mandrel, gauge pin, or a Lee collet die mandrel. Of course, if your bullets are consistent in size a dummy round can work (I prefer to avoid a soft bullet as a reference of any kind.)

With a mandrel inserted, I measure the OD in several locations as I rotate it in the mic. I choose the largest bushing that is at least 0.xxx” smaller than the smallest OD I measure on any neck in the sample. How much smaller wil be determined by what you had stuck in the neck. If it’s a regular expander mandrel (-0.001 under bullet size), you only need a bushing another 0.002 smaller. Depending on neck hardness, this should give a neck size that always guarantees some tension and also assures the neck is the slightest bit yielding when the bullet seats so that ultimate tension is set by metallurgy and not by geometry.

I find the .2885 of my honed Forster to be exactly perfect for my brass in 6.5.