Hey guys quick question. I mostly self taught and now that I'm getting into neck tensions I haven't been to happy with the donuts forming after a couple reloads. So is it possible to use just a FL sizing die with the expander ball removed and then run a mandrel to dial in neck tension from the inside. I have a mandrel now but there seems to be some spring back and leaves me with more tension than using bushings. I was looking a a set from 21st Century reloading and it looked like it would fit the bill. Is all this common knowledge and I'm just showing up a little late to the game? Or am I missing something.
Mandrels
- Thread starter ofdscooby
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Yes you can use a mandrel to set the neck tension you're looking for.
Deputy819
Well-Known Member
Yep….mandrels or bushings will accomplish what you want here, but realize that you're just setting a mechanical "interference" fit between the bullet and case mouth. There's no way any of us can know specific "neck tension" unless we know the actual non-linear hardness state of the case mouth in question.
If you want a larger set of mandrels for dealing with varyijng tempers of brass you may want to contact Porter's Precision Products, LLC for a set of mandrels. portersprecisionproducts.com.
Revolting Peasant
Well-Known Member
Mandrel Dies – Porter's Precision Products
portersprecisionproducts.com
Yes. Madrels are the way to go. All my brass is annealed. I calculate my brass thickness, select the correct bushing and then finish the sizing with a mandrel. My SD's are all single digit now.
QuietTexan
Well-Known Member
What you describe is possible. But when using a standard FL die (meaning not honed), they tend to make the necks very undersize. The measurement you're looking to manage in this process is TOTAL movement of the neck OD.
For example, using a 308 caliber case, FL and mandrel combo:
- Loaded OD = 0.338".
- Fired OD = 0.344", so +0.006" from loaded.
- FL Sized OD: 0.332", so -0.012" from fired.
- Mandrel up to final sized OD of 0.337", so +0.005" from FL sized.
- Seat bullet to loaded OD of .338", +0.002".
- Total neck movement is 0.025" (sum of the absolute value of each movement, aka total movement in AND out)
If you changed the FL die for a bushing die, insead of reducing to 0.332", it reduces to the bushing size of 0.336", so 0.004" less of down sizing with the die, and 0.004" less of up sizing with the mandrel. Net 0.008" less movement, total movement is now 0.017". Once a chamber is cut you can't control expansion during firing (except to make it more by neck turning), so the die/mandrel combination is what you have to work with.
Why it matters - moving brass hardens it. Annealing is required to reset neck hardness. Even if you anneal, moving the necks more than necessary can lead to poor concentricity and makes necks/shoulders more likely to split.
Not that those risks are any worse than using an FL die with button, or even FL die with mandrel. You just won't maximize the benefit of using the mandrel without pairing with a bushing die. If the downsides don't impact your shooting enough, rock and roll with FL and mandrel.
I have several complete caliber kits from 21st Century, and they're very good tools. Out of something like 40+ mandrels only one was out of spec, and it was most likely mis-marked and not cut wrong - they sent me a replacement no questions askeed. I highly recommend them, great company to work with.
Porter makes a good set, also. I prefer the 21st Centruy mandrel style and the die that those use versus the collet design, but that's a nit-pick on my side and nothing against Porter.
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bonie
Well-Known Member
I'v read the responses above, and didn't see any mention of neck turning, i did see mention of annealing and both are important
I shoot short range bench rest and do both. I have seen even quality brass that require turning, this helps insure uniform pressure around the hole neck. Cheaper brass can have pretty extreme thickness variation. it all counts in our game when we are trying to put 5 rounds in the same hole five matches in a row. good luck read alot and keep asking questions.
I shoot short range bench rest and do both. I have seen even quality brass that require turning, this helps insure uniform pressure around the hole neck. Cheaper brass can have pretty extreme thickness variation. it all counts in our game when we are trying to put 5 rounds in the same hole five matches in a row. good luck read alot and keep asking questions.
