Bushing Die Creating False Shoulder Issues

[Brandon05_88]

Last two range trips, I've had odd issues with my brass. Carbon is covering the shoulder and sometimes making it to the case head. Even getting ejector swipes with mild loads in the 42.0 to 43.0 grains H4350 range with 140 Hybrids. I measured multiple pieces of fired brass, and the headspace was slightly shorter after firing.

Rifle is an AI AT in .260 Rem. Brass is 4x fired Lapua annealed each firing and sized in a Redding Type S Full Length with .292 bushing and floating carbide expander. I suspected donut, but the bullet with enter most all cases. However, some fired cases the bullet will not enter at all. Case length is just above minimum trim length. Necks measure 0.298 at the base, 0.296 at the middle, and 0.294 at the mouth. Rifle was chambered with a 0.298 neck reamer. I suspected a carbon ring in the chamber after the first range trip with issues, so I cleaned the chamber and throat area and verified no carbon ring via borescope.

I see a shiny ring at the neck shoulder junction when the portion of sized neck ends. With the lowest portion of the neck being the same diameter as the chamber, I'm suspecting the bushing die. How do you solve this? Slightly smaller bushing? Go to a normal full length die?

 

[Steel head]

I don’t think a bushing die is capable of sizing 100% of the neck.

sounds like you have an outside donut.

You could neck turn it.

The problem you have now won’t get fixed with a standard die because it will just push the material inside the neck.

I played with bushing dies for a bit.
I wasn’t impressed.

 

[Brandon05_88]

It’s exactly an outside donut. I really like the bushing die as sizing is nearly effortless, and bullet seat like butter.
Which die did you go to?

 

[918v]

If you’re annealing each firing then just use a standard FL die and ditch the expander ball and go with an expander mandrel. That way your neck will be sized all the way to the shoulder.

 

[trophyhunter]

What is your measurement at the shoulder body junction ?
Fired & sized

if carbon is getting to that area you might have a die that is sizing the shoulder body junction to much. This expansion on firing will cause pressure, it’ll show in the base, primer & ejector area.

 

[Tokay444]

If a bullet won’t slip into a fired case without effort, I would neck turn.

 

[Brandon05_88]

What is your measurement at the shoulder body junction ?
Fired & sized

if carbon is getting to that area you might have a die that is sizing the shoulder body junction to much. This expansion on firing will cause pressure, it’ll show in the base, primer & ejector area.

Measurements at the shoulder body junction on fired is 0.453 and sized is 0.449. To be fair, maybe 10-20% had the carbon make it past the shoulder body junction. Most had carbon stop 1/16” above the body shoulder junction. Almost like it was head spacing at the base of the neck and body shoulder junction without the shoulder really making much contact. These last 2 range trips were the only time this has happened in a year and a half and 1000 rounds using the bushing die. I’m leaning towards the outside donut as the culprit.

 

[Timo Turl]

You need to neck turn.

 

[918v]

I doubt it.

 

[trophyhunter]

Measurements at the shoulder body junction on fired is 0.453 and sized is 0.449. To be fair, maybe 10-20% had the carbon make it past the shoulder body junction. Most had carbon stop 1/16” above the body shoulder junction. Almost like it was head spacing at the base of the neck and body shoulder junction without the shoulder really making much contact. These last 2 range trips were the only time this has happened in a year and a half and 1000 rounds using the bushing die. I’m leaning towards the outside donut as the culprit.

To me .004” on the body is a lot. I look for .0005-.001” with .002” being the max that I’d use a die. If you call your die company they’ll most likely get you a die that fits your chamber better.

what is your base at the .200” doing fired & sized ? I know for my 308 barrel that I was just measuring fired was .4705 and sized was .469”. I tested a small base die and that ran my base to .468. What I’m gettin at is .002” is on the upper end of movement for brass.

I can’t see after 1000rds which I’m assuming was with same brass, now you’re having a donut issue that was never the case before.

 

[Brandon05_88]

@trophyhunter
Fired is 0.469, sized is 0.468. Reamer was a standard SAAMI .260 Rem with 0.298 necks and 0.110 freebore. Die is a typical Redding type S full length. I don’t want a custom die as I’ll likely pull this barrel in another year or two.

I can see where the die basically just kisses the case at the web. The die does knock the sheen from annealing off at the shoulder body junction.

This is actually the second lot of 100 I’ve ran through the rifle. First lot of 100 was junked after 6-7 firings due to case head separation soon due to bumping about 3 thou or so. This second lot of 100 has 3-4 firings.

I like to keep things as simple as possible, so I seriously doubt I’ll get into neck turning. I’d rather go to a regular FL die than neck turn.

 

[trophyhunter]

@Brandon05_88 No custom does for me either. i called Redding with a 223 Improved 40 die. Told the super nice man what I was experiencing, he said to send in my die and 3 fired cases, he’d get one that matched best. I also had my reamer specs and good measurements on what the die was doing. They were super helpful.

 

[trophyhunter]

Based on quick search your shoulder on your fired brass is perfect, .4539”, my best guess and assumption to losing brass so soon is that excessive bump to .449” on the shoulder/body junction.

Even at bumping shoulders .003” shouldn’t cut your life that short on good brass. On some of my Lapua brass, running in moderate pressure I’m at 22x firings. Majority of my match brass is at 8x firings. Never once had a case head separation.

 

[whatsupdoc]

If you cannot inset a bullet into your fired cases then it is either there is something in the neck area of the chamber, the brass neck is too thick or the chamber neck is tight.

With the brass at .294 the bullet should slide in easy. I would double check the chamber neck area for carbon.

 

[Brandon05_88]

In all fairness, I was running them quite hot. 140 Hybrid with 44.1 H4350 in Lapua with BR2 at 2.950”. I was getting average 2912 FPS in a 26” Bartlein and TBAC can. Both of those 100 rounds lots have seen that load. I’ve just decided to back down to the 42.5ish node for 2800 FPS.

 

[digrazir]

I had the same issue with my AI AT 260 Remington with Lapua brass. The bullet would not drop freely into a fired case...donuts...I full length sized the brass and turned the neck down to .0135. Now I full length size and use an expander mandrel. The fliers went away too. Ray

 

[Brandon05_88]

The bullets that wouldn’t enter the case stopped at the mouth. The boat tail wouldn’t even enter the neck. Coulda been a dinged neck from ejection.
New FL die arrives today. Gonna stick with the floating carbide expander for the Redding dies.

 

[digrazir]

The new 260 Lapua brass has .015 neck thickness out of the box...Unless you neck turn your problems will continue..probably not what you want to hear...Ray

 

[Brandon05_88]

Even with a chamber neck of 0.298”?

 

[digrazir]

The only math you need to worry about is the fact that the neck thickness on your Lapua brass is too thick for your chamber...your fired brass won’t accept a bullet..turn your necks and your problems will go away..end of story...Ray

 

[918v]

The bullets that wouldn’t enter the case stopped at the mouth.

The more you fire the harder the neck gets. The case mouth starts to curl inward, decreasing in diameter.