Case mouth belling after FL sizing

[Dusty Stevens]

That’s quite a bit to size the neck down. I don’t think it has anything to do with your issue, just an observation.

It has everything to do with it actually. I can do the same move with any bushing die if i squeeze it down far enough

 

[Hoot]

Have you tried a case that was not annealed? I induction anneal and I have observed that the mouth seems to get the hottest, based upon color and behaves a little more softer than the rest of the neck. Yours may not be springing back in that area after leaving the expander portion of the die.. That having been said, I've experienced slight flaring when as already suggested, I'm sizing the neck a long ways down. I only use sizing dies with bushings and none of my sizing dies have expanders in them. I'm a mandrel man. Lastly, I don't suppose you're looking to add more steps to your process but I bought a .308 that has a generous neck. When sizing my annealed, fired cases, I do two passes with successively smaller bushings. If that 308 wasn't so damned accurate as is, I'd have it set back and rechambered with a less generous neck.
My best advice would be to lose the expander and add a mandrel step to your process. If you go with self-tapered pin gauges, its not too expensive to tool up for.

Good Luck,

Hoot

I doubled with Dusty...

 

[Ray123]

Pictured ...More than one problem, FL die, the case is flared during sizing, ...but Seating die produces dings and still flared after seating, problem #2.
Check disassemble seating die and look for burrs and metal brass shavings, clean and polish die.... maybe.
OR: Simple test....Use another die set ...Your problems will probably disappear...if your cases are in spec.
I actually had the same appearance on seating die, dull reamer left heavy burr at the top of the die neck, flaking off brass and getting worse with continued use.

 

[Will Henry]

It really sounds like your sizing die is a little short and there is a step at the front. The case is getting crimped slightly when sized then flared when the expander goes through. If this is not the case, I'm at a loss. Very weird. WH

 

[ToddKS]

Expander button - 0.2630"

Inside neck diameter:

• 0.2620" - Fired
• 0.2600" - FL sized with expander
• 0.2550" - FL sized no expander

Outside neck diameter:

• 0.2940" - Fired
• 0.2880" - FL sized with expander
• 0.2850" - FL sized no expander

0.2900" - Loaded with 123gr Scenar
0.2915" - Flared mouth lip after FL w/expander and seated 123gr Scenar

(measurements at mid-neck)

The inside neck diameter with no expander would be enough for me to discard the die regardless of any other issues. There is no need to work the brass like that.

If it were me, I would replace the die with a Redding S type with the appropriate bushing and move on.

 

[DiRTY DOG]

The inside neck diameter with no expander would be enough for me to discard the die regardless of any other issues. There is no need to work the brass like that.

If it were me, I would replace the die with a Redding S type with the appropriate bushing and move on.

Agree. I have a honed Forster on order.

 

[Dave M.]

It has everything to do with it actually. I can do the same move with any bushing die if i squeeze it down far enough

Hmm I stand corrected then Dusty. I assumed that flare must be coming from the expander button and main shaft because he said when he removes it, the flare is gone. I assume this is a bushing die, and the OP already stated that it isn’t possible to get the mouth to the flared portion of the center stem.

 

[shoot4fun]

Wrong. I listed my exact loading process above.

With NO tumbling, NO vibrating, NO trimming, and NO chamfering, a fired case exits the FL sizing die with the case mouth flared as shown and described.

I looked at your process before my initial post and knew it said nothing about cleaning the brass but, IMO, if the pictured stick of brass has been fired, then annealed and run through a FL die and still comes out looking that shiny I want to know how.
My suggestion would still be to try the same process with chamfered stick of same brass. You may be surprised.

 

[DiRTY DOG]

Hmm I stand corrected then Dusty. I assumed that flare must be coming from the expander button and main shaft because he said when he removes it, the flare is gone. I assume this is a bushing die, and the OP already stated that it isn’t possible to get the mouth to the flared portion of the center stem.

Not a bushing die. The Mighty Armory FL die is a fixed die. The expander assembly cannot be adjusted at all up or down, it fits into the die body just like a mandrel and the top lid screws down to fix it secure.

 

[DiRTY DOG]

I looked at your process before my initial post and knew it said nothing about cleaning the brass but, IMO, if the pictured stick of brass has been fired, then annealed and run through a FL die and still comes out looking that shiny I want to know how.
My suggestion would still be to try the same process with chamfered stick of same brass. You may be surprised.

The pictured case was dry tumbled, but the same exact flaring happens with no cleaning at all. The flaring only happens when the expander is used in the FL die.

 

[Webster]

My case mouths are slightly belled out after FL sizing with the expander button assembly. There's a lip all around the mouth that catches when trying to close the bolt. Usually the bolt won't move forward completely without a good shove forward. Fired brass is ejected without the mouth belled out.

6.5x47L
Lapua brass (now 2x fired)
Mighty Armory FL sizing die with decapping rod & expander
RockChucker press

My process for fired brass:
1. Anneal
2. Lube inside neck with Imperial dry lube
3. Lube outside with Imperial wax
4. FL size with the expander, 2 thou shoulder bump measured with comparator
5. After that I trim/chamfer... New brass was below trim to depth and still is now.

Cases exit the FL die with the case mouth flared out. This happens without any trimming or chamfering. Straight out of the FL die.

If I remove the decapping/expander assembly, and FL size fired brass, the mouths are NOT flared out. The mouths are only belled out when using the decapping/expander assembly.

I'm puzzled and have never seen this before. What am I doing wrong?

I don't shoot competition. I don't understand why you need an expander or mandrel. Sounds like sizing the neck twice. I deprime with an old FL die with the decapping pin screwed down so it removes the primer without any sizing, then size with a bushing die. My varmint rifles shoot round groups under 0.400". Firing should make the neck round and conform to the accurately machined chamber. Not going to get OCD on springback comments. Never measured any of this stuff. Do you think the die sqeezing the neck down then pulling a mandrel thru the neck gives a better dimension than the bushing alone? The mandrel is attached at the top of the die and hangs down about two inches, There is no way to center it in the die within a few thou. The slop in the threads probably determines it's alignment.

 

[Dave M.]

The pictured case was dry tumbled, but the same exact flaring happens with no cleaning at all. The flaring only happens when the expander is used in the FL die.

Are you sure the stem cannot contact the die? Do you have some blue chem? Or possibly a sharpie would work. Heavily mark the mouth area with sharpie and then you should be able to see the corresponding marks on the stem or die that are causing the issue.

 

[Dave M.]

Not a bushing die. The Mighty Armory FL die is a fixed die. The expander assembly cannot be adjusted at all up or down, it fits into the die body just like a mandrel and the top lid screws down to fix it secure.

Perhaps the brass is longer than the die can accommodate and therefore is touching the stem somewhere it shouldn’t

 

[Dave M.]

I don't shoot competition. I don't understand why you need an expander or mandrel. Sounds like sizing the neck twice. I deprime with an old FL die with the decapping pin screwed down so it removes the primer without any sizing, then size with a bushing die. My varmint rifles shoot round groups under 0.400". Firing should make the neck round and conform to the accurately machined chamber. Not going to get OCD on springback comments. Never measured any of this stuff. Do you think the die sqeezing the neck down then pulling a mandrel thru the neck gives a better dimension than the bushing alone? The mandrel is attached at the top of the die and hangs down about two inches, There is no way to center it in the die within a few thou. The slop in the threads probably determines it's alignment.

I will preface this statement by saying that I DO NOT USE mandrels, nor do I think they are needed for ultra accurate ammo. However, the thought behind the mandrel is that any variation in neck thickness is pushed to the inside of the neck with a neck bushing, therefore this surface is no longer a perfect circle. Then by using a mandel, that variation in neck thickness is pushed to the outside of the case mouth, where it in theory has very little effect. I buy and shoot only the best brass, and I neck turn most of it; therefore, I don’t prescribe to the above theory. But to answer your question, that is the main reason to use mandrels.
Dave

 

[Dave M.]

OP, to answer one of your questions, the bushing in a FL bushing should never be locked down. It free floats and thus is self aligning.
Second, is it possible the area shown below with the red arrow is just barely contacting the case mouth on the full down stroke? I’d color that area on the stem with a sharpie and I think you will see scratch marks on it after sizing. Let us know what you find.

 

[DiRTY DOG]

OP, to answer one of your questions, the bushing in a FL bushing should never be locked down. It free floats and thus is self aligning.
Second, is it possible the area shown below with the red arrow is just barely contacting the case mouth on the full down stroke? I’d color that area on the stem with a sharpie and I think you will see scratch marks on it after sizing. Let us know what you find.
View attachment 1381398

1. It's not a bushing die. Pretty sure I've noted that a few times here already.
2. Of course it contacts the case moth at the rex arrow, because that is the expander button.

 

[M-61]

Am I reading your numbers right? That the fired case inside neck diameter drops
in size .0040 upon firing?

Nice catch. It pays to read carefully

 

[Dave M.]

1. It's not a bushing die. Pretty sure I've noted that a few times here already.
2. Of course it contacts the case moth at the rex arrow, because that is the expander button.

Sorry the bushing comment was directed at Webster and trying to answer his inquiry.
Dirty dog, save your the time of diagnosing the problem and throw that POS die in the trash and move on. Lol. Good luck.

 

[Webster]

I will preface this statement by saying that I DO NOT USE mandrels, nor do I think they are needed for ultra accurate ammo. However, the thought behind the mandrel is that any variation in neck thickness is pushed to the inside of the neck with a neck bushing, therefore this surface is no longer a perfect circle. Then by using a mandel, that variation in neck thickness is pushed to the outside of the case mouth, where it in theory has very little effect. I buy and shoot only the best brass, and I neck turn most of it; therefore, I don’t prescribe to the above theory. But to answer your question, that is the main reason to use mandrels.
Dave

Could you comment on a couple thoughts I have. Isn't the forcing cone at the front of the chamber about 1-1.5 thou larger than the bullet? Without looking it up I believe the forcing cone angle is only 1 or 2 degrees taper to position the bullet? Is a 24" barrel the final swaging operation to determine the final shape and alignment of the bullet? Does the bullet traveling down a barrel and being engraved by the rifling over ride any finicky neck preparation?

 

[Dave M.]

Could you comment on a couple thoughts I have. Isn't the forcing cone at the front of the chamber about 1-1.5 thou larger than the bullet? Without looking it up I believe the forcing cone angle is only 1 or 2 degrees taper to position the bullet? Is a 24" barrel the final swaging operation to determine the final shape and alignment of the bullet? Does the bullet traveling down a barrel and being engraved by the rifling over ride any finicky neck preparation?

Almost always 1.5 degrees.
I don’t understand your second question.
The third question is debatable. We all strive to make perfectly concentric ammo and I have shot my most concentric and least concentric ammo (4 thou delta in TIR) against each other and noticed no difference at 600 yards. I’ve performed this test several times over the past 5 years. It’s a good way for me to use up ammo that has been made with larger TIR.
Dave