Build up at case neck shoulder junction. Need help

[DKing11316]

New to neck turning.... Lapua 6.5 creedmor brass was new when turned to .0135 turned slightly into shoulder. Once fired, now have brass build up at shoulder case neck junction. Anyone have any ideas why this is happening?? Any help would be greatly appreciated. Fired from a GAP 6.5 creedmoor if that is of any help.
trimmed to 1.910, Berger 140 hybrid, h4350 at 42.0 grains. no pressure signs at primer.

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[DKing11316]

5 shot Group with said load during development.

 

[Steel head]

21st century neck turner deals with that.

 

[DKing11316]

They were turned on 21st century lathe into shoulder. Talked to John said he has never seen this before.

 

[DKing11316]

Prior to firing.

 

[Milo 2.5]

You run them through a bushing die to set tension?

 

[DKing11316]

Redding type s bushing die set the tension to.002.

 

[DKing11316]

Using a .287 bushing.

 

[Steel head]

They were turned on 21st century lathe into shoulder. Talked to John said he has never seen this before.

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All my cases look similar but a bit less severe than that but nothing like first pic posted.
do you have a grov on your chamber neck.
I've seen that before.

 

[Milo 2.5]

Redding type s bushing die set the tension to.002.

The bushing, being it is beveled is doing this. Are you bottoming it out on shoulder?

 

[DKing11316]

the redding die that I used with a slight cam over does not resize the whole neck only about 85%. from what I understand they don't resize the whole neck. And I do not believe there is a groove in the chamber. rifle was built by gap with about 300 rounds down the tube. brass never did this until neck turning.

 

[delfuego]

Are you using the expander ball? Is the bushing rattling inside the die? Is there writing on the bushing? If so is the writing up or down?

 

[Steel head]

the redding die that I used with a slight cam over does not resize the whole neck only about 85%. from what I understand they don't resize the whole neck. And I do not believe there is a groove in the chamber. rifle was built by gap with about 300 rounds down the tube. brass never did this until neck turning.

Pic looks like your getting into the shoulder a bit much.
I doubt gap would put out a crappy chamber job.
Bushing dies often get build up like first pic.
Thats is why I do not use them.

 

[DKing11316]

No expander ball. GAP puts out a great product gun shoots awesome. bushing rattles slightly and the letters are down inside the bushing. Steel head what do you recommend for dies, open to ideas.. thanks for the replies..

 

[delfuego]

I had a similar issue recently. I remedied it using the ball/mandrel and a smaller bushing. I cleaned annealed and re-sized everything. I shot all the brass. After firing and resizing, this time with my normal bushing I had straight brass without the donut.

 

[DKing11316]

Delfuego PM Sent

 

[DKing11316]

Again thanks to everyone for the replies!!

 

[L.R.Novice]

I'm only have a little experience turning necks but I've always attributed the bump to the case lengthening. The thicker unturned wall that was at the shoulder has extruded into the neck. I typically fireform the brass before I neck turn to reduce the lengthening and therefore the bump.

 

[DKing11316]

Makes sense. I'll give that a try. Thanks

 

[Steel head]

No expander ball. GAP puts out a great product gun shoots awesome. bushing rattles slightly and the letters are down inside the bushing. Steel head what do you recommend for dies, open to ideas.. thanks for the replies..

I'm an uncouth savage, I use a Lee collet and Redding body die.
bushing dies work great in tighter necked chambers but in field friendly chamber I always fought minor issues.

 

[Changed]

Is this the expanded but unsize portions of the neck? I inquired about this in the past. I've been told that some BR and F-Class Shooters use this as a benefit to centering the cartridge in the chamber. When I set my sizing die up, I tighten the bushing down until I can barely hear a rattle. This insures some float in the die. If this fits in your chamber, and you still shoot good groups, I would not worry about it. The real issue is when the bulge is inside the neck. Then you need a neck turner like the 21st century that has a reamer that goes in the neck.

I too would agree that tight custom chambers would be less of an issue than sloppy factory or "Field" chambers. I'm a novice reloader, but have studied this phenomenon.

 

[TripleBull]

Then you need a neck turner like the 21st century that has a reamer that goes in the neck.

I assume you mean that the 21st Century turner has a mandrel that goes into the neck. I'm going to pick up the Wilson trimmer and their reamer to deal with donuts that form inside the neck.

 

[Horns8491]

The old saying is: "when you hear hoofbeats, think horses, not zebras." Thinking your problem might be the GAP is like thinking albino midget transsexual unicorns.

Going into the shoulder with the 21st century tools never made sense to me. I know the blade is angled up to accommodate the shoulder, but if you just keep going you will eventually cut all the way through the shoulder. I might see if I could test one or two new pieces of brass neck turned but not going into the shoulder at all.

 

[Steel head]

The old saying is: "when you hear hoofbeats, think horses, not zebras." Thinking your problem might be the GAP is like thinking albino midget transsexual unicorns.

Going into the shoulder with the 21st century tools never made sense to me. I know the blade is angled up to accommodate the shoulder, but if you just keep going you will eventually cut all the way through the shoulder. I might see if I could test one or two new pieces of brass neck turned but not going into the shoulder at all.

It a nice feature if your necking up brass.
Often the the thicker shoulder formed into neck forms an immediate donut.
More so with lapua and similar brass but even so to a smaller degree with my beloved Winchester brass.

 

[TripleBull]

Going into the shoulder with the 21st century tools never made sense to me. I know the blade is angled up to accommodate the shoulder, but if you just keep going you will eventually cut all the way through the shoulder. I might see if I could test one or two new pieces of brass neck turned but not going into the shoulder at all.

As long as you are careful, I don't think you'll cut through that neck/shoulder junction. If you are full length sizing with an expander button, that area of the brass is moving towards the mouth and you actually get thickening of the neck as the brass from the shoulder is sort of extruded into the neck. That's a bit of a generalization but holds true for many that FLS. I like the plan of not using an expander ball for that reason - you're not working the brass at the neck/shoulder junction as hard and not pulling it into the neck as much.

 

[Changed]

I assume you mean that the 21st Century turner has a mandrel that goes into the neck. I'm going to pick up the Wilson trimmer and their reamer to deal with donuts that form inside the neck.

No, what I mean is that most neck turner have mandrels that slip in the case and have a smooth taper. The 21st Century version has a mandrel with a cutter on the tip. it evens out any "Donuts" on the inside of the case neck.

 

[Jimgal62]

I use the 21st neck turner with Whidden full length bushing dies on Lapua brass. Have not seen any donuts.

 

[DKing11316]

I was thinking about making the switch to full length dies. How often do you anneal?

 

[TripleBull]

No, what I mean is that most neck turner have mandrels that slip in the case and have a smooth taper. The 21st Century version has a mandrel with a cutter on the tip. it evens out any "Donuts" on the inside of the case neck.

I own a 21st Century neck turn lathe and don't believe the mandrel has a cutter tip. I can't find it on their site. Got a link?

 

[DKing11316]

I would be interested in this as well, following.

 

[Milo 2.5]

I own a 21st Century neck turn lathe and don't believe the mandrel has a cutter tip. I can't find it on their site. Got a link?

When I bought mine, they did not offer an inside cutter, look to K&M, drop in fit, if a donut is visible on the outside of the case, most likely on the inside too.

 

[TripleBull]

When I bought mine, they did not offer an inside cutter, look to K&M, drop in fit, if a donut is visible on the outside of the case, most likely on the inside too.

I'd looked at K&M, but in the wrong spot - I'd looked under mandrels. Looked again after seeing your post and found it here:

http://kmshooting.com/carbide-cutting-pilot.html

Thanks.

 

[_Raining]

I thought the letters on the bushing were supposed to be up in the die.

edit: I was wrong, from thier instructions it should be down.