50 BMG + Triebel Dies = Too much Neck Tension?

RedBreast21

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Context: I'm a pretty sophisticated reloader (though I'm an idiot sometimes and make mistakes). I precision hand load for everything from .223rem through .338LM. For measurements (this is relevant for this post), I use Mitutoyo ball and tube micrometers and calipers, and have (negative)pin gauges for measuring IDs through .625".

I am, however, brand new to reloading for 50BMGs. I am using once-fired (by me) Hornady brass, and using Triebel Dies (and imperial wax). My first attempt at resizing a piece of brass was very difficult, even for the needed increased force for 50bmg (in my mind). The resulting case ID was .505 (which seems to be about .002 too much). But even more concerning than the resulting ID was the sheer amount of force I needed to use to get the case back out of the die.

Enter, the pin gauges and ball micrometer. I measured the ID of "neck portion" of the FL die to be .536". The case wall thickness is .0224". Doing the math, that leads to an initial ID (before it hits the expander ball) of .4912"=.536-2(.224). The expander diameter is .508 (which matches Triebel's specs).

The die's neck diameter seems to be significantly undersized compared to the expander (which also seems to be undersized for the caliber), but, again, I'm brand new to 50bmg. The only discussion I found about 50bmg neck tension suggested a neck tension of .003. whereas if I loaded the brass as is, I'd be right at .005.

I don't have access to RCBS or any other brands' dies. Does anyone have measurements for those dies or any other thoughts about what I'm seeing (including whether I'm an idiot . . .).

I'd appreciate any thoughts from experienced 50bmg loaders, with thanks in advance.

(other potentially relevant details: Loading 750 AMAX with diameters of exactly .510, confirmed measurements)
 

918v

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Did you break the die in? If not that’s the reason for the excessive sizing effort. The bigger the bullet diameter the more neck tension you need. It’s all normal.
 

acudaowner

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no pics it did not happen . besides what is too much the brass unless flattened or crushed will expand to let the bullet inside and it's only so tight not like it's ever going to crush the bullet . and it will let go of the bullet at some point allowing the bullet to go down range you might get higher numbers , do they make expanding mandrels for .50 cal ? if so let the mandrel do it's job and open it to your desired neck tension . Best of luck please share pics or what answer you go with finally .
 

KZP

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I don't have pin gauges but my interior is showing .506 with calipers using the RCBS resizing die.

Couple questions:
  • Are you annealing your brass?
  • What lube are you using on the interior/exterior?
  • Which press are you using?
 

RedBreast21

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Nov 24, 2020
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I don't have pin gauges but my interior is showing .506 with calipers using the RCBS resizing die.

Couple questions:
  • Are you annealing your brass?
  • What lube are you using on the interior/exterior?
  • Which press are you using?
Thanks for the info. It sounds like the final neck dimension may not be as tight as I thought - I still wish it didn't compress the neck so much initially.

The questions:

I did not anneal this test piece, but will be annealing (my AMP is a Gen 1 which doesn't handle 50BMG, but my buddies all have Gen 2's, so for as often as I shoot 50, they're (one in particular) is willing to let me use his AMP for my 50BMG cases.

I'm using Imperial Wax on inside/outside.

The press - unfortunately - is an Ammomaster 2. I have tried - and tried - and tried, to get the gentleman at Prazi to take my money, but they have gone completely silent on me.
 

RedBreast21

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The bigger the bullet diameter the more neck tension you need. It’s all normal.
O.k. Thanks.

The die isn't broken in yet by any stretch (pun intended), but it's been cleaned and lubed. I was just so surprised at the amount of force I needed to get it past the mandrel that I started measuring because it seemed way off.
 

KZP

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Thanks for the info. It sounds like the final neck dimension may not be as tight as I thought - I still wish it didn't compress the neck so much initially.

The questions:

I did not anneal this test piece, but will be annealing (my AMP is a Gen 1 which doesn't handle 50BMG, but my buddies all have Gen 2's, so for as often as I shoot 50, they're (one in particular) is willing to let me use his AMP for my 50BMG cases.

I'm using Imperial Wax on inside/outside.

The press - unfortunately - is an Ammomaster 2. I have tried - and tried - and tried, to get the gentleman at Prazi to take my money, but they have gone completely silent on me.

I anneal every shot, maybe that helps.

Try Imperial on the outside and the ceramic media + dry lube for inside. Quick spin in the media for a light coat then wax on outside. Don't cake it on or it becomes hard to get it back out of the die. Worked better for me than wax on inside. Faster than sticking a q-tip in there trying to get consistent coverage. I don't clean my brass until after ~6 firings, a little carbon inside the neck grabs dry lube better.

Is your sizing button galled or have excess brass collecting?

Here is a clip of sizing to give a reference point on effort with RCBS dies. I've gotten in the habit of going slow on reverse stroke because it was loosening my sizing button when slamming it back down, but it comes out with little effort.

 

RedBreast21

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Nov 24, 2020
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I anneal every shot, maybe that helps.

Try Imperial on the outside and the ceramic media + dry lube for inside. Quick spin in the media for a light coat then wax on outside. Don't cake it on or it becomes hard to get it back out of the die. Worked better for me than wax on inside. Faster than sticking a q-tip in there trying to get consistent coverage. I don't clean my brass until after ~6 firings, a little carbon inside the neck grabs dry lube better.

Is your sizing button galled or have excess brass collecting?

Here is a clip of sizing to give a reference point on effort with RCBS dies. I've gotten in the habit of going slow on reverse stroke because it was loosening my sizing button when slamming it back down, but it comes out with little effort.

Thank you for all of this, KZP. I will try what you have suggested, and I appreciate the video very much! I need to apply a significant amount more force than shown in your clip, and I appreciate having that as a reference. Will update when I have more info.