I use the gauge pin that should give me the desired ID. I then try other pins to measure the actual ID (considering spring back). I document what pin I used for sizing and what pin gave me the actual "post sizing" dimension. Shooting will tell me what pin to use for sizing. The key is to keep good records.
- Thread starter FNG1001
- Start date
Sounds like we do the same....cheers
I'm in the camp of it's more about the consistency of neck tension than it is about the number. I'm sure if a guy had the time to test every neck tension there would be a benefit but I don't so I just set it and forget it.
I did see smaller groups and lower ES/SD when I went to a mandrel so I stick with it.
I use the 21st century turning arbor in my no man bun 
My groups went from about 1/2 to 3/8" consistently. I can't say for certain if it was the mandrel or I just became a better shooter. Either way It makes me feel warm and fuzzy.
Oh, I surely don't do that...when I determine the mandrel needed for the interference I want via the pin gauges, I then just batch process the brass.
Oh, not I. But, I am a retired old fart and producing the best reloads I can has become a bit of a hobby/challenge? Though I am holding the line at using water to check case capacity, neck turning, and bullet meplat trimming! haha
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When I made this switch I was also switching from a single stage press with a redding bushing die to a dillon 550 progressive and a full length (non bushing) hornady die, my primary concern was bullet runout and I found I had fewer cases showing any/as much. That was 3 years ago, I don't recall a significant difference in my groups at distance on steel but they certainly didn't get worse.
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Many great shooters , that's why they sell . People that shit on mandrels mostly do so out of frustration because they can't shoot the difference . I don't bother with mandrels when sizing for my Mini-14 , but I sure do use them when I want to shoot small with my bolt guns .
My rifles are all modest.
My rifle shooting, I'd give it a good rating nothing better.
I fl size and basically use the expander to prestraiten case mouth. I undersize and polish the expanders to a mirror finish, it gives a much smoother sizing operation.
The mandrell step brought several different guns from 7/8 - 3/4 inch best to 1/2 - 3/8 inch for a price of about 35$, I'm impressed.
I may be at the top of my expectations for skills and equipment at that and I'm comfortable in my skin.
I believe there are two reasons for some shooters to not be able to realize any improvement by using a mandrell.
1. You have very good equipment and top notch skills allready shooting well under 1/2 groups.
You have hit your limmit and only have chrono numbers left to play with.
Or.
2. Your shooting skills need improved or you have a bad piece of equipment preventing you from seeing a difference.
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Mine stayed the same from .05moa to under 3/8moa when I eliminated the mandrel. Trending in the 1/4moa region.
Have you shot again without the mandrel.
No.
Probably never will again.
Got to get my 35$ worth out of that die.
Probably never will again.
Got to get my 35$ worth out of that die.
IMHO, a mandrel is a relatively benign process step, not to annoying, and frankly probably necessary to have tool anyway (to fix damaged or dented necks), so I don't think people getting weird about them makes any sense.
There's a lot more things that can go wrong with shoulder bumps, if we look at tolerances of...dies, lock rings, lubricants, pre/post annealing hardness, speed/ duration of forming action, press setups, etc...not to mention all these people claiming to measure HS to the 1 thou ...with a tool that oesn't have the true ability to resolve 1 thou anyway....
There's a lot more things that can go wrong with shoulder bumps, if we look at tolerances of...dies, lock rings, lubricants, pre/post annealing hardness, speed/ duration of forming action, press setups, etc...not to mention all these people claiming to measure HS to the 1 thou ...with a tool that oesn't have the true ability to resolve 1 thou anyway....
Not sure what amount of evidence you would be satisfy with given your indicating you have seen better results once you eliminated the mandrel.
If i had to guess your neck bushing has a higher interference fit than the mandrel you used. The additional neck tension had positive results. You could try going down another .0005 with the mandrel.
The purpose of the mandrel
1 Adjust the amt of neck tension on a consistent basis.
2 Expand the brass, and with the expansion, move any anomalies on the inside of the neck to the outside.
3 With the interior of the neck free of issues bullet seating will be the same as well as bullet release.
IF you are able find the right mandrel size and achieve the above your results will show on paper.
Trevor
I wouldn’t say better. Just not worse. I have the mandrel in case I encounter a damaged mouth, but ultimately I’ve eliminated it from my regular process.
My runout numbers tell me I have no anomalies inside the neck that need to be pushed outwards.
My runout numbers tell me I have no anomalies inside the neck that need to be pushed outwards.
I disagree.
You should get several sizes. Bullet seating pressure is affected by several variables: neck hardness, neck wall thickness, neck wall surface condition, neck ID prior to expanding, etc. Having expanders in different sizes makes life easier. It’s like having different bushings for your bushing die.
If you’re using a standard FL die then different size expanders are almost mandatory.
If you’re using a standard FL die then different size expanders are almost mandatory.
When I’m loading for classes I run all my brass through my Dillon with only a mighty armory decapper and a sinclair mandrel during the prep phase, I’ve found I’ve gotten much better and more consistent loads.
When doing precision loads I use k&m mandrells and a Redding die with neck bushings.
When doing precision loads I use k&m mandrells and a Redding die with neck bushings.
Ok, but if you were forced to choose one as a starting place vs 5 or 6 in .0005 increments for 5 or 6x more coin: what would your alternative recommendation be?
Turning arbors are .002 under bullet diameter and have always given me great results with ~.002 of interference fit +/- .0005 or so on the micrometers for everything I’ve ever stuck one in.
I haven’t felt the need to go chasing. I suppose if one doesn’t anneal then yeah, they would need to get an assortment, or just see if the load needs to be tuned at the start the loading cycle and most likely find that it’s still fine.
If your normal die is sizing way to far I’d say a better investment would be in the sizing die to stop it from sizing too far, not trying to remedy that symptom by swapping mandrels.
Nailed it , do it right in the first place and remove a variable .
I don’t look at it that way. A die oversizing a case is not a problem necessarily. I see it as a case/die mismatch.
I don’t like bushing dies, btw.
If you’re sizing a case using a bushing die with a bushing that takes the neck down .002” below loaded diameter, then a turning mandrel is perfect. The reason is it’s not doing much.
But if you’re sizing down more, say .004”+, then having additional size mandrels is a big help.
I would get mandrels .0005”, .001”, .0015”, .002” under bullet diameter. And not the coated ones because they can’t be adjusted if necessary. The quoted diameters are never spot on.
Recently I loaded up 100rds my usual way using a mandrel and another 100rds that were identical except I skipped the mandrel…
I could hit the same size plates from 300-1250 yards, and no surprise, a good wind call and/or good trigger press seemed to matter more than anything else…
That said, whether at 100 or 1000 yards, my groups were smaller with the stuff that had seen the mandrel, and over the chrono the mandrel’d stuff gave me an SD of 4, while the non-mandrel’s stuff yielded an SD of 7.
Was the performance different enough to matter? IDK, depends, in my case the mandrel seems to be worth the time, and since it’s maybe the easiest and least annoying reloading step I do, I’ll keep doing it…
I could hit the same size plates from 300-1250 yards, and no surprise, a good wind call and/or good trigger press seemed to matter more than anything else…
That said, whether at 100 or 1000 yards, my groups were smaller with the stuff that had seen the mandrel, and over the chrono the mandrel’d stuff gave me an SD of 4, while the non-mandrel’s stuff yielded an SD of 7.
Was the performance different enough to matter? IDK, depends, in my case the mandrel seems to be worth the time, and since it’s maybe the easiest and least annoying reloading step I do, I’ll keep doing it…
Adding a twist.
I ran a similar test using a 100x prepped with a FL sizing die (with the expander ball), and another 100x prepped with FL sizing (no expander ball)+mandrel giving me 0.002 tension. No appreciable difference in MV. I'll look into groups on my next range trip.
What kind of FL sizing die?
You're not proving anything if you just stop expanding the necks and change neck tension on a developed load. I could not see a difference, on paper or chrono, between an expander mandrel and expander ball of the same size.
Forster's normal FL sizing die in 6 dasher.
Not trying to prove anything. I wanted to see if my extra brass prep steps (3 vs 1) did anything different for my loads. Our results are the same.
How much is that die sizing the neck, fired dia vs sized dia?
*vs loaded
If his forster dasher matches mine it’s .265”. I sent mine off to be honed without first using it asking for .265 and they mailed it right back telling me that already was their spec on it. Now I check before shipping lol
But what is the fired dia and loaded dia? How much is it moving the brass?
What I’m trying to see is how much the expander is working the neck.
I’ll let him speak for his but here is mine with lapua. In this case, basically none at all. Sometimes the miti calipers will read .2665, I can feel it touch but it’s light and is really just fine for feel good reasons.
But in the case of the 6 creed that came with too much and I’ve failed to send it off yet it makes a world of difference
Thanks.
So there will be no difference between mandrel, ball, or nothing at all. Because there is no dimensional change.
In your 6cm you will benefit from a -.001” expander over a -.002” because the bullet will seat easier and the seater stem won’t mark up the bullet nose.
So there will be no difference between mandrel, ball, or nothing at all. Because there is no dimensional change.
In your 6cm you will benefit from a -.001” expander over a -.002” because the bullet will seat easier and the seater stem won’t mark up the bullet nose.
But it already doesn’t now and is nice and smooth, would probably the same with the ball. I do need to get this thing shipped off for a hone though.
But like baron said, it’s the easiest step in my reloading, I’ll do it out of dogma now because it can only make the worse ones better and the best ones won’t change.
I don’t disagree that testing mandrel steps is the way to get the best, but for most who are fine with good enough the turning arbor is a fine first choice to see if it meets a persons needs before further investment
But like baron said, it’s the easiest step in my reloading, I’ll do it out of dogma now because it can only make the worse ones better and the best ones won’t change.
I don’t disagree that testing mandrel steps is the way to get the best, but for most who are fine with good enough the turning arbor is a fine first choice to see if it meets a persons needs before further investment
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I think there's a difference between all the different methods, but the difference may be smaller than one might think.
In my mind, the main popular methods are: squashing the necks too much and then pulling up on the shoulder/necks with an expander ball (traditional FL die w/ expander ball), versus just squashing the neck as little as is needed and doing nothing else (FL bushing die), versus squashing the necks a tiny bit too much on purpose and then pushing through the necks going down so the shoulder has the most rigidity to hold its shape (honed-FL or bushing die followed by a mandrel die). More and more I'm starting to think that if one anneals every firing, one might be able to just pick one of the second two...
Brass is relatively malleable, and we're stuffing it in a steel chamber and then causing an explosion that yields thousands of pounds of pressure which blows it out to custom-fit the chamber it was just blown up in... so I'm not confident the minute differences matter as much as some might think. Arguably, a little more or less neck tension when the round was made means nothing when faced with all that pressure once the firing pin drops. However, I think how the round initially fits in the chamber is important, I want the same fit every time if I can before the big boom, so I prefer the methods that distort the shoulder the least (no expander ball).
For me, I think using the mandrel helps me make each round come out as near-identical to the next as I can, so I'll continue to use it, but I don't think it's the huge deal I once did.
In my mind, the main popular methods are: squashing the necks too much and then pulling up on the shoulder/necks with an expander ball (traditional FL die w/ expander ball), versus just squashing the neck as little as is needed and doing nothing else (FL bushing die), versus squashing the necks a tiny bit too much on purpose and then pushing through the necks going down so the shoulder has the most rigidity to hold its shape (honed-FL or bushing die followed by a mandrel die). More and more I'm starting to think that if one anneals every firing, one might be able to just pick one of the second two...
Brass is relatively malleable, and we're stuffing it in a steel chamber and then causing an explosion that yields thousands of pounds of pressure which blows it out to custom-fit the chamber it was just blown up in... so I'm not confident the minute differences matter as much as some might think. Arguably, a little more or less neck tension when the round was made means nothing when faced with all that pressure once the firing pin drops. However, I think how the round initially fits in the chamber is important, I want the same fit every time if I can before the big boom, so I prefer the methods that distort the shoulder the least (no expander ball).
For me, I think using the mandrel helps me make each round come out as near-identical to the next as I can, so I'll continue to use it, but I don't think it's the huge deal I once did.
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0.272 fired
0.266 sized
For the most part, I agree.
In my quest to understand internal ballistics and how neck tension is involved, it's become apparent to me that neck tension effects the timing for the blowby at the low pressure point when the bullet is first being released. "All that pressure" happens long after the bullet has been release and some of the gasses have already escaped by way of the blowby that happens before "all that pressure".
Neck tension isn't the only factor there as seating depth also effects the timing of the blowby. Since neck tension can be an important issue, like other aspects involve, consistency is really the name of the game. 
