I bought some 284 brass that was necked "Down' to 6MM and I want to neck it back "Up" to 7mm. What is the best way to do this?? I tried a 6.5 button in my 7MM die but the necks are crooked. SOoooo.. Can you guys help me out?? What do I need to bring my necks back to 7MM and still keep them straight??
Best way to expand case necks???
- Thread starter Raptor
- Start date
BoydAllen
Gold $$ Contributor
If you have an old barrel, to use for fire forming, and a good backstop that you can walk up close to, load them at 6mm with a regular powder for use with that load, and fire them in a 7mm barrel. That should get them close enough that you can use a 7MM expander to finish the job, and it will give you the straightest results. I have done this to form 6PPC cases from .220 Russian Brass, using .22 bullets. BTs seat much straighter with a mismatched seater.
You may need two expander mandrels; one'd be 6.5mm / .260" & the other 7mm / .284". Typically these are smaller at the start than 3/8" - 1/2" up the shank so as to be gentle on brass. A 6.5mm ought to start out small enough to start the process on 6mm necks.
(I'd offer to measure one of mine but I'm 200+ miles away from home for a few days....)
They're meant for press use where the mandrel gets inserted into the necks. Pulling a sizing die expander ball up through a case neck invites distortion owing to the (relative) lack of support at the shoulder and the very small contact area of the ball itself.
I'm a fan of these products:
https://www.kmshooting.com/catalog/case-neck-expanding-tools/expand-iron_complete.html
- but there are other brands that work essentially the same way:
http://www.21stcenturyshooting.com/3_8_Expander_Die_Body.php
http://www.sinclairintl.com/reloading-equipment/case-preparation/neck-turning/turning-expander-mandrels/index.htm
Depending on how carefully these cases were necked down, and how many times they've been fired since, you may want to anneal the necks before expanding them too to avoid cracks.
Necking down will thicken necks so they're often turned a little bit to even them up & reduce neck wall thickness. You should check into this as necking up will cause necks to thin a little as the brass flows to its new shape. If your cases have been turned already, expanding them may get you necks thinner than you'd prefer for your chamber(s).
(I'd offer to measure one of mine but I'm 200+ miles away from home for a few days....)
They're meant for press use where the mandrel gets inserted into the necks. Pulling a sizing die expander ball up through a case neck invites distortion owing to the (relative) lack of support at the shoulder and the very small contact area of the ball itself.
I'm a fan of these products:
https://www.kmshooting.com/catalog/case-neck-expanding-tools/expand-iron_complete.html
- but there are other brands that work essentially the same way:
http://www.21stcenturyshooting.com/3_8_Expander_Die_Body.php
http://www.sinclairintl.com/reloading-equipment/case-preparation/neck-turning/turning-expander-mandrels/index.htm
Depending on how carefully these cases were necked down, and how many times they've been fired since, you may want to anneal the necks before expanding them too to avoid cracks.
Necking down will thicken necks so they're often turned a little bit to even them up & reduce neck wall thickness. You should check into this as necking up will cause necks to thin a little as the brass flows to its new shape. If your cases have been turned already, expanding them may get you necks thinner than you'd prefer for your chamber(s).
CatShooter
Raptor said:
You cannot use a standard expander for this.
Redding makes a special tapered expander button to bring the neck up to 7mm - it will not ruin the neck - it is easy peasy.
http://www.midwayusa.com/product/872356/redding-tapered-size-button-16283-7mm?cm_vc=ProductFinding
If you don't have Redding FL sizing die to use it in, you need to get one....
CatShooter
Raptor said:
No, no... it will work in either - I have used them and they work fine !! Put a little lube on the inside of the neck.
CatShooter
Raptor said:
Thanks for the invite - First, I gotta shoot all the alligators that are chompin at my ankles
CatShooter
Raptor said:
Neither one of us is grown up - but he is going into college in sept.... and I am as old as dirt!
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