Question Regarding Expansion Mandrels

[Timon]

I am currently using 21st Century Expansion Mandrels and have been for quite a while now. I switched to a Short Action Customs modular bushing sizing die recently. On this die, SAC uses a mandrel that replaces the decapping rod and pin.

I was going to switch to SAC mandrels for this die, but got to thinking that they would set the ID on the downstroke of the press ram. I have always read that it is better to use a mandrel that sets the ID on the upstroke of the ram. SAC makes fantastic tools and their sizing die is fantastic, just not sure about this mandrel thing.

I contacted SAC about this and they told me the best possible use of a mandrel, is an instantaneous handoff of the neck from the bushing that sets the OD, to the mandrel that sets the ID. Just not sure what to think of this. I suppose it sounds reasonable, but I have always read and subscribed to the theory, that the case is stronger with the mandrel being pushed into it, rather that being pulled out of it.

Just looking for some others thoughts on this.

Thanks

Scott

 

[RustyInBend]

I agree with SAC ... I use a Redding Type-S FL Bushing die to size the case and neck, and then immediately mandrel out to my final seating diameter. It's a formula that's worked really well for me.

 

[jds holler]

I think you're getting into the "how could you possibly tell the difference" zone. jd

 

[RegionRat]

As often as not, we have seen poor quality brass with uneven wall thickness that didn't matter what was used it would have runout.

 

[RustyInBend]

I think you're getting into the "how could you possibly tell the difference" zone. jd

I tell the difference because I use an AMP Press that gives me great detail on my seating pressure, so that I can go up or down in bushing and/or mandrel to hit the target seating pressure that gives me my best SD and most consistent velocity.

 

[RustyInBend]

As often as not, we have seen poor quality brass with uneven wall thickness that didn't matter what was used it would have runout.

I use Lapua and Peterson, and get very low runout in my long-range calibers. I don't doubt the cheaper the brass ... the greater the expected runout. No disagreement.

 

[6Creed73]

I love their stuff, but I disagree with SAC on this one. Setting ID on the downstroke can mess with the shoulder bump, especially if it's not a smooth transition. I've experienced this myself and used a comparator to confirm it. It doesn't always happen, but it certainly can.

Not only do I use a separate expander mandrel, I wait until I'm ready to use that brass before setting the neck with the mandrel. Awhile ago, I was experiencing varying pressures while seating bullets. What I found out was if I let the brass sit around for an extended period of time after sizing/mandrel, the necks would change over time causing inconsistent seating. Annealing helps with this, as does only using the mandrel when I was ready to load the brass. Ever since I started doing that, my bullet seating is very consistent.

 

[RustyInBend]

I love their stuff, but I disagree with SAC on this one. Setting ID on the downstroke can mess with the shoulder bump, especially if it's not a smooth transition. I've experienced this myself and used a comparator to confirm it. It doesn't always happen, but it certainly can.

Not only do I use a separate expander mandrel, I wait until I'm ready to use that brass before setting the neck with the mandrel. Awhile ago, I was experiencing varying pressures while seating bullets. What I found out was if I let the brass sit around for an extended period of time after sizing/mandrel, the necks would change over time causing inconsistent seating. Annealing helps with this, as does only using the mandrel when I was ready to load the brass. Ever since I started doing that, my bullet seating is very consistent.

Apologies if I misunderstood. Using a bushing die and using a Mandrel are two different steps, with two different dies. I size, then I mandrel.

 

[6Creed73]

Apologies if I misunderstood. Using a bushing die and using a Mandrel are two different steps, with two different dies. I size, then I mandrel.

Correct. I was responding to the OP who was asking about expanding the neck in the same step...like with an expander ball. He mentioned that SAC stated he should not do this in separate steps.

 

[Timon]

I think you're getting into the "how could you possibly tell the difference" zone. jd

I asked for a real answer, to a legitimate question, your response provided very little help regarding my question. Sir, you do not know me, nor my shooting abilities, but I assure you that I can tell if there is a difference in my loads.

Thank you.

 

[Timon]

I love their stuff, but I disagree with SAC on this one. Setting ID on the downstroke can mess with the shoulder bump, especially if it's not a smooth transition. I've experienced this myself and used a comparator to confirm it. It doesn't always happen, but it certainly can.

Not only do I use a separate expander mandrel, I wait until I'm ready to use that brass before setting the neck with the mandrel. Awhile ago, I was experiencing varying pressures while seating bullets. What I found out was if I let the brass sit around for an extended period of time after sizing/mandrel, the necks would change over time causing inconsistent seating. Annealing helps with this, as does only using the mandrel when I was ready to load the brass. Ever since I started doing that, my bullet seating is very consistent.

I agree with you, thus the reason I posted this.

I’ve had several knowledgeable people in the field tell me that this SAC method is second to none. As you indicated, I am concerned this action will affect my shoulder setting.

What they are saying I believe, is that the mandrel expansion takes place at the same time the bushing is working the O/D of the neck. In a way, I understand what they are saying, as the I/D is expanded before the case begins it’s descent along the mandrel. In the case of a “ball”, the expansion takes place when the withdraw of the case is at about a 3/4 piont (give, or take) down the rod.

If what they are saying is true, it would cut out a step in the reloading process. I’m just not sure if I fully buy into it or not.

I do agree with you regarding not letting the brass “rest” before completing the reloading. I also found that it led to inconsistencies in the neck tension/seating force required. That led to inconsistencies in the release of the bullet.

I’m still mulling this thing over. For the time being anyway, I’ll do it in separate steps.

Scott

 

[6Creed73]

I agree with you, thus the reason I posted this.

I’ve had several knowledgeable people in the field tell me that this SAC method is second to none. As you indicated, I am concerned this action will affect my shoulder setting.

What they are saying I believe, is that the mandrel expansion takes place at the same time the bushing is working the O/D of the neck. In a way, I understand what they are saying, as the I/D is expanded before the case begins it’s descent along the mandrel. In the case of a “ball”, the expansion takes place when the withdraw of the case is at about a 3/4 piont (give, or take) down the rod.

If what they are saying is true, it would cut out a step in the reloading process. I’m just not sure if I fully buy into it or not.

I do agree with you regarding not letting the brass “rest” before completing the reloading. I also found that it led to inconsistencies in the neck tension/seating force required. That led to inconsistencies in the release of the bullet.

I’m still mulling this thing over. For the time being anyway, I’ll do it in separate steps.

Scott

I'm not familiar with this particular die from SAC, but I'm going to check it out. I'm not fully understanding how sizing the OD and ID can happen at the same time, unless it acts kind of like the Lee collet die does, where a collet presses the neck against a mandrel. If it's not using a traditional ball expander, I'd have less apprehension about using it. If it is in fact, a mandrel and not a ball, I'd be interested in trying it...just not going to pay SAC prices for an experiment.

 

[mikecr]

Mandrel use is an extra sizing step, using a mandrel die.
This & any method of expansion occurs after downsizing.
Mandrels reduce the chances of pulling necks off center, as can happen when standard die buttons are pulled through necks.

 

[Timon]

I'm not familiar with this particular die from SAC, but I'm going to check it out. I'm not fully understanding how sizing the OD and ID can happen at the same time, unless it acts kind of like the Lee collet die does, where a collet presses the neck against a mandrel. If it's not using a traditional ball expander, I'd have less apprehension about using it. If it is in fact, a mandrel and not a ball, I'd be interested in trying it...just not going to pay SAC prices for an experiment.

Not cheap, that for sure. If I recall the die was around $375 and the mandrels are $50 each.

 

[avidflyer]

Been using the SAC die since it was introduced….Done a lot of work with it and have made several observations….. first using their die produces very little run out, was pretty impressed. second if you look at the design of the mandrel it has a pretty good taper on it, enters the brass with no stress, the shoulder and neck gets sized (plus overall brass) on the upstroke (ram rises) then on the downstroke the mandrel gets pulled through the neck of the brass. I use a combination of 2-3k neck smaller bushing then the mandrel as to not over work the brass. Third it seems that when I sized with a Forester neck honed die and used a mandrel in a separate step the brass never seemed to lengthening, (grow) using this die if measure before and after sizing brass grows on average 2k, have seen 3k seems like I’m pulling the neck on the downstroke, Vs when I do it with a mandrel pusing in. One thing I dont like about the dies are the way they size and shape the shoulder. The die seems to leave a very sharp shoulder, not that it’s shaving the brass but very sharp. Hard to describe I’ll take some pictures. Sharper then any die I’ve ever used. The bushing these die use are not standard, they have the shoulder and neck bulit into the bushing. It’s like a Al Warner clone / copy. (typed on my phone hope it makes sense)

 

[Timon]

Been using the SAC die since it was introduced….Done a lot of work with it and have made several observations….. first using their die produces very little run out, was pretty impressed. second if you look at the design of the mandrel it has a pretty good taper on it, enters the brass with no stress, the shoulder and neck gets sized (plus overall brass) on the upstroke (ram rises) then on the downstroke the mandrel gets pulled through the neck of the brass. I use a combination of 2-3k neck smaller bushing then the mandrel as to not over work the brass. Third it seems that when I sized with a Forester neck honed die and used a mandrel in a separate step the brass never seemed to lengthening, (grow) using this die if measure before and after sizing brass grows on average 2k, have seen 3k seems like I’m pulling the neck on the downstroke, Vs when I do it with a mandrel pusing in. One thing I dont like about the dies are the way they size and shape the shoulder. The die seems to leave a very sharp shoulder, not that it’s shaving the brass but very sharp. Hard to describe I’ll take some pictures. Sharper then any die I’ve ever used. (typed on my phone hope it makes sense)

I have the die and really like it, I have just been a bit confused on the mandrel set up with the die. I’m thinking that I’m just going to break down and buy a couple of mandrels for the die and conduct some testing with them vs the standard type of mandrels. Thank you so much for your input!

Scott

 

[jds holler]

I said - I think you're getting into the "how could you possibly tell the difference" zone. jd

I asked for a real answer, to a legitimate question, your response provided very little help regarding my question. Sir, you do not know me, nor my shooting abilities, but I assure you that I can tell if there is a difference in my loads.

Thank you.

And -- I apologize, and certainly meant no offense. I made a very off-hand comment about something that seemed to be almost a "fly poop vs pepper" detail, and failed to consider that I'm often a neanderthal in these circles. I'll pull my nose out of here and let y'all get back to a productive discussion. jd

 

[Rat Rifle]

Being of German descent, no one appreciates quality tools more than I. The SAC Die is a quality tool, as it should be, considering the cost. The die is an attempt at theoretical perfection. It’s success depends on the case neck walls being concentric and parallel.

This is best achieved by using the IDOD CASE TRIMMER. Otherwise, successful results can be achieved by using easier and cheaper equipment.

After every match, I look at the results to see who performed better than Me. Usually a long list. It’s not surprising to get beat by the best shooter with the worlds greatest equipment. But when I get beat by a guy shooting his HUNTING rifle, I have to wonder how much of this theory and perfection is beneficial and necessary.

As long as we are having fun striving for ballistic perfection, all is good.

JUST MY OPINION..WHAT ELSE COULD IT BE

 

[Timon]

I said - I think you're getting into the "how could you possibly tell the difference" zone. jd


And -- I apologize, and certainly meant no offense. I made a very off-hand comment about something that seemed to be almost a "fly poop vs pepper" detail, and failed to consider that I'm often a neanderthal in these circles. I'll pull my nose out of here and let y'all get back to a productive discussion. jd

Thank you sir, all is well. Happy shooting

 

[avidflyer]

Being of German descent, no one appreciates quality tools more than I. The SAC Die is a quality tool, as it should be, considering the cost. The die is an attempt at theoretical perfection. It’s success depends on the case neck walls being concentric and parallel.

This is best achieved by using the IDOD CASE TRIMMER. Otherwise, successful results can be achieved by using easier and cheaper equipment.

After every match, I look at the results to see who performed better than Me. Usually a long list. It’s not surprising to get beat by the best shooter with the worlds greatest equipment. But when I get beat by a guy shooting his HUNTING rifle, I have to wonder how much of this theory and perfection is beneficial and necessary.

As long as we are having fun striving for ballistic perfection, all is good.

JUST MY OPINION..WHAT ELSE COULD IT BE

On non neck turned brass I'm getting less than .001 run out and most is half that. Basically whatever the variance in neck wall thickness is. I have, do and will continue to turn some calibers of brass, the last 400 pieces of 308 srp have all been within a half to full 1k so didn't bother