Bushing Size Question

[AHart76]

I am sure this has been covered before, but I googled around and couldn’t find the answer I was looking for.

I am using a bushing resizer for the first time. It’s a Redding Type S FL bushing sizer. I am necking 6.5 Creedmoor down to 25 Creedmoor. I have Alpha brass that I will use for actual cartridges, but I tried resizing some 6.5 Hornady brass so I don’t mess up my $1 a piece brass. The neck thickness on the Hornady brass was ~0.0135. So, by my math, [(0.0135+0.0135)+0.257)-0.002=0.282.

When I use the 0.282 bushing, however, it comes out to 0.279. I am using Hornady Case Lube and I cleaned the die&bushibg before using. Obviously the expander mandrel and decapping pin assembly is removed.

What could be causing the die to size the neck down 0.003 more than the bushing size? Is it possible the bushing is wrong? Could there be too much lube on the case necks taking up 0.003?

Any advice is appreciated!

 

[AHart76]

So after doing some more measuring, the brass is actually somehow flaring out at the end. It is 0.279 through most of the neck and the flaring out to .282 at the opening. I’m not even sure how this is possible?

 

[spife7980]

Not unheard of, the end of the neck has less material around it to hold it and gets more springy

 

[MarinePMI]

Or, in necking down to 25 caliber, you've created a doughnut in the neck (which is probably what Spife is alluding to). An inside neck reamer would resolve that.

 

[spife7980]

Nope and I would never inside ream. Get nasty scratches all over the inside of the neck when you drag that reamer back out. Although the old lee reamer where you inserted the brass into a sizing die so that it had outside case support and then ream is the only way I would ever even consider it.

And a doughnut is at the base of the neck anyways, and if that was his issue I would say it’s because it’s a bushing and doesn’t size the neck completely. And when sizing down doughnuts shouldnt be an issue because you are essentially extending the shoulders forward until the hit the smaller neck diameter and so neck material is being transitioned into those new shoulders. It’s sizing up where you flare that shoulder material out to creat the new wider neck that doughnuts should become an issue. Obviously exceptions to everything but in general...

The end of the neckflaring is due to brass spring back and its wanting to hold the memory of its prior state, the wider neck. Annealing would help that as it relieves the material stresses in the brass and thus helps reduce spring back.

What I cant answer is why the rest of the neck is sizing down .003 more than the bushing but maybe the bushing is in upside down? I know some bushings aren’t perfect on top of the chamfered opening but still. Might want to measure again again?

 

[MarinePMI]

Spife,

Interesting perspective.

Yes, I was referring to the old Lee inside neck reamers (only inside reamers I've ever used). In fact, I'm surprised Lee hasn't started making them again for their "quick trim" dies; it'd seem like peas and carrots for them.

As to the doughnut, necking down can cause a doughnut. As the neck is sized down, material is pushed up towards the case mouth. As material shifts, the shoulder material moves into the lower neck. This is a fairly well known thing with some cases (.308 to .260 or 7mm-08 is an example where it occurs with certain manufacturers brass). With the 25 CM, I am unsure of the case dimensions, so I can't say empirically that this is occurring, just that it's a possibility.

I'm not saying you're incorrect in your assessment, because frankly, I'm not familiar enough with the 25 CM dimensions. I'm just saying that necking down does in some cases produce a doughnut. Just like necking up doesn't always produce neck doughnuts. It really depends on parent case being used, in conjunction with the dimensions of the new case being formed (and where that shoulder moves, or material moves, as the case is being formed).

 

[AHart76]

The thing that got me was that I was using a .282 bushing. It was necking the majority of the neck to .279 and the opening would be flared to .282, bushing size. So spring back didn’t make sense to me. After more extensive googling I found some articles of other people having this same issue.

One even spoke to Redding, and they said that is was because he was trying to neck down too much in one step, causes the brass to move too much all at once.

The Hornady brass I was using was once fired from my 6.5. For the sake of science and experimentation, I decided to run 10 pieces of the virgin Alpha through it. The necks on them came out to .281 with the mouth still flared to .282.

Starting outside diameter of the Alpha was .288. I didn’t measure starting outside diameter of the Hornady. Don’t know why I didn’t.

After some more measuring of the Alpha brass, though, the brass thickness is .014-.0145. I ordered a .283&.284 bushing from Midway that should be here tomorrow. The .283 should give me the desired .002 of neck tension for a PRS gun. Hopefully the larger bushing will also move the brass less and fully alleviate the problem.

I will keep you all updated!

 

[918v]

Necking down does not create a doughnut. Necking up creates doughnuts.

WTF is the purpose of a .25 Creedmoor?

 

[918v]

So after doing some more measuring, the brass is actually somehow flaring out at the end. It is 0.279 through most of the neck and the flaring out to .282 at the opening. I’m not even sure how this is possible?

It’s possible. That’s what happens when you use bushing dies. The brass flows along the contour of the bushing, beginning at the champher, which imparts the curve to the case mouth. It does not go away and you end up with a trumpet.

 

[MarinePMI]

Necking down does not create a doughnut. Necking up creates doughnuts.

Sorry, but a blanket statement like that is false. The devil is in the details.

 

[AHart76]

Necking down does not create a doughnut. Necking up creates doughnuts.

WTF is the purpose of a .25 Creedmoor?

Use the new Blackjack 131 Ace bullet. G7 of .330. Should be a pretty sweet cartridge. They have several of them out. It by no means is the end all-be all, and the 6.5&6 Creedmoor are both great cartridges that are well proven. Building a wildcat of sorts just sounded like fun to me. 25CM has the obvious ability to perform just as good as the other Creeds as long as I do my part. Working with Logan and Miles of Blackjack Bullets has been a real pleasure. I’m always happy to support a new small business run by people who are pationate about their product.

 

[918v]

Sorry, but a blanket statement like that is false. The devil is in the details.

It is not false. Please explain how necking down creates a doughnut.

 

[MarinePMI]

If a case is drawn with tapering walls, and a case is sized down with the shoulder being pushed back, then the thicker brass will end up as part of the bottom of the neck. This happens with 6.5CM made from .308 for example.

 

[918v]

That’s a stupid example.

The OP is not making 25CM from a FC308 case. He is necking down 6.5 to .25 on an existing CM case. He’s not running into thick case body walls.

 

[spife7980]

If a case is drawn with tapering walls, and a case is sized down with the shoulder being pushed back

To be fair I wouldnt call that necking down, thats into what I would call case forming and yes, anything goes there. Going from 6.5 creed to 6 creed shouldnt give you a doughnut. I wouldnt expect 260 from 308 to either, thick necks requiring turning, sure, but not a donut in the typical sense unless you are moving the shoulder back more than necessary or it is done on many times fired cases where the shoulder material has had the chance to migrate forward.

 

[918v]

OP,

I suggest you neck down using a 6.5CM Lee Collet Neck Die with the decapping rod removed. No trumpet effect. No lubing. No problem.

 

[spife7980]

OP,

I suggest you neck down using a 6.5CM Lee Collet Neck Die with the decapping rod removed. No trumpet effect. No lubing. No problem.

Does lee make a 6.5 collet die, I didnt think that they did? And wouldnt you also need the rod installed for the collet to clamp down around? And as such wouldnt you need to sand it down to size or replace it with a 25 cal rod?

 

[MarinePMI]

To be fair I wouldnt call that necking down, thats into what I would call case forming and yes, anything goes there. Going from 6.5 creed to 6 creed shouldnt give you a doughnut. I wouldnt expect 260 from 308 to either, thick necks requiring turning, sure, but not a donut in the typical sense unless you are moving the shoulder back more than necessary or it is done on many times fired cases where the shoulder material has had the chance to migrate forward.

Hmmm...pretty common to see a doughnut when going from .308 to .260. There's quite a few folks that have run into that here.

 

[AHart76]

I think if I switch to the .283 bushing, it will alleviate the flaring problem. This should only be an issue on this first initial necking down. After the brass has been fire formed once, the brass won’t moving near as much and should resize no problem.

As far as the donut, I have talked to several people who necked 6.5 brass down to 6mm. They never had any issues. I am taking these from .264 internal to .257. I don’t think I have anything to worry about. If that happens, I may be doing a caliber change as neck turning and internal turning is not something I was looking to get into.

 

[MarinePMI]

That’s a stupid example.

The OP is not making 25CM from a FC308 case. He is necking down 6.5 to .25 on an existing CM case. He’s not running into thick case body walls.

You asked for an example, you got it. As stated, what are the case dimensions of the 25 CM?

As for stupid...well, that is your opinion. LOL! Have fun with that (since I gave you an example, go ahead and keep back tracking...)

 

[MarinePMI]

Does lee make a 6.5 collet die, I didnt think that they did? And wouldnt you also need the rod installed for the collet to clamp down around? And as such wouldnt you need to sand it down to size or replace it with a 25 cal rod?

They do. It comes in their pacesetter die set, but can be ordered by itself direct from Lee.

 

[918v]

Does lee make a 6.5 collet die, I didnt think that they did? And wouldnt you also need the rod installed for the collet to clamp down around? And as such wouldnt you need to sand it down to size or replace it with a 25 cal rod?

No you don’t need a .25 cal rod, just adjust the die differently. You’re going to have to expand the neck with a mandrel anyway.

 

[918v]

You asked for an example, you got it. As stated, what are the case dimensions of the 25 CM?

As for stupid...well, that is your opinion. LOL! Have fun with that (since I gave you an example, go ahead and keep back tracking...)

I wasn’t back tracking. Your example was stupid because it involved reforming the case walls into a shoulder and forcing the 3x thick brass into the neck.

This is not an issue with necking down the 6.5CM because the thin neck brass continues into the shoulder. Section a case.

 

[MarinePMI]

No shit, really?

Your blanket statement, when applied to necking down any case, is patently false. That was my fucking point.

In this case, it is not false, but again, the devil is in the details.

Quit being a douche. Just stop.

 

[918v]

Are you familiar with the following term: CONTEXT ???

Your “blanket statement” BS doesn’t apply here. All posts within a thread are made in the context of the original post.

 

[MarinePMI]

Sigh. Sure. Whatever.

Please refer to the : "Quit being a douche" comment.

Not...

 

[Kevin.N]

So after doing some more measuring, the brass is actually somehow flaring out at the end. It is 0.279 through most of the neck and the flaring out to .282 at the opening. I’m not even sure how this is possible?

Does it get uniform after you use the expander?

Just to be sure you say that most of the neck is at 0.279 but at the mouth it's 0.282( and you made sure you were not measuring the outside burr of the mouth)?