Hey guys, I use a forster honed die with no expander, followed by a sinclair carbide expander mandrel for most of the calibers I reload, and up to this point it hasn't given me any problems. I noticed the other day that since I leave the mandrel die body set in one spot and simply change the mandrels, my shorter 6 BRA wasn't getting the neck fully expanded. I adjusted the die down so that the entire neck would be expanded, but it seems to be pulling the headspace back out of my brass now, to the tune of about .003". I've tried no lube, dry lube, and my typical lanolin / alcohol mix. They all pull the shoulder back out. maybe because the neck is so long it has a lot of drag? Any ideas? I'm thinking about just running the forster expander button but I'd like to get the mandrel working if I can!
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Sinclair Expander Mandrel Problems
- Thread starter Mnash
- Start date
Seems to me that withdrawing the case from the mandrel while pulling the shoulder out .003 would take an awful lot of force. I don’t see how a lubed case neck could grab the mandrel that hard. Something else is going on. What’s the neck OD before and after taking a trip over the mandrel? For me the difference is about .001, and its one fingers worth of effort to do so.
It does cause chambering issues, that’s how I first noticed it, I have to really cam down on the bolt handle to get it to close. If I just run the brass through the sizing die it chambers easily, as soon as I run the same piece over the mandrel and go to chamber it that’s when it won’t fit. The die is honed to .264” and my brass is .025” total thickness. That means my ID goes down to .239” and the. Is brought back up to .242” nothing drastic. There is a measurable difference in shoulder position using a Sinclair bump gauge after mandrel use
Every thought of using a bushing die, and just selecting the bushing so you don’t have to do so much expander work?
Was just studying the hide to see if mandrels were goin to fit into my routine.
Just recently read that one of the key features was it did not move shoulder.
All the high math aside, what is od of a neck before and after?
I was going to use a mandrell in a dillon and do my brass prep on the single without the expander installed.
Just recently read that one of the key features was it did not move shoulder.
All the high math aside, what is od of a neck before and after?
I was going to use a mandrell in a dillon and do my brass prep on the single without the expander installed.
Also what size mandrell you are using? You arent just using the expander and or turning mandrel right?
The neck OD changes by about a thou after spring back, and I don’t have a tight neck chamber so that shouldn’t be an issue. Plus, the bullet really expands the neck out to its final OD, so if I’m having chambering problems with just an empty case and only on the camming downstroke of the bolt and not simply getting the neck to go into the chamber, something else is going on besides neck OD
So let me math this 0.025+0.025+0.243=0.293 would be your loaded round dimater
Die honed to 0.264
0.293-0.264=0.029 inches of difference, that is a LOT of sizing your neck is probably gonna get pulled out of alignement and moved unless that mandress size is pretty small
Die honed to 0.264
0.293-0.264=0.029 inches of difference, that is a LOT of sizing your neck is probably gonna get pulled out of alignement and moved unless that mandress size is pretty small
That is really odd, could you just measure the mandrel to confirm? Also does the mandrell have any galling with brass embedded?
Try chucking the mandrel in your drill press and polish the shaft with 500 or greater emory paper. I’ve had this issue also. This is my fix. I also use Imperial wax on a qtip and swab the inside of the neck every other case.
David
David
there it is
Stop annealing you destroyed the ability of the case to retain its shape its soft enough to chew
Thats not annealing that is overannealing. Although it sounds like you found the culprit.
There’s no galling on the mandrel, I Did get galling on a stainless mandrel but that’s why I switched to carbide, it would be hard to imagine brass affecting carbide. I will try polishing it though and see if that helps. As far as the annealing I only anneal until my 750 tempilaque goes clear, no further, and I’ve also tried unannealed brass with the same results
Mandrels you shouldn't need to worry about neck thickness - that's when you're dealing with a bushing on the OD of the neck.
The expander mandrel is I think .001" under bullet size, so for a .243 the .242" mandrel should be right, with springback giving you maybe .0015" neck tension? If you're dealing with fired brass though, you might need to neck size down, and then expand out with the mandrel.
Also, annealing every firing is completely fine, assuming it's done correctly and you don't overheat the brass.
The expander mandrel is I think .001" under bullet size, so for a .243 the .242" mandrel should be right, with springback giving you maybe .0015" neck tension? If you're dealing with fired brass though, you might need to neck size down, and then expand out with the mandrel.
Also, annealing every firing is completely fine, assuming it's done correctly and you don't overheat the brass.
Good annealing article:
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annealing to 750 deg is cumulative in that one firing/reload cycle is not enough to sufficiently reharden the brass. So if you anneal every time then after a few reloads the case gets too soft. I went through this years ago. Now I anneal maybe once or twice throughout the life of the case .
hmm interesting, thats why hydro seating press is useful, its gonna tell you thst your brass is soft
The die has a collet that squeezes the case neck around the recapping rod. As the collet compresses around the neck, the neck offers resistance to sizing, though slight. A normal neck will feel differently than a soft neck. A normal neck will resist the collet and will let you feel it bottom out against the decapping rod. A soft neck will just feel like mush. It will offer no resistance and you won’t feel it bottom out. A really soft neck will also ooze past the collet and lengthen and thin out the neck. That die creates a lot of pressure.
You can 100% feel the difference if your cases are too hard.
You can actually feel it spring back against the press if brass is hard.
Also if you turn it a bit and hit it again annealed brass will feel dead on the second hit.
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