Necking down problems
- Thread starter Bedrok
- Start date
Necking down Norma 300 WSM to make 7MM WSM. I’ve done this exact same process lots of times before and had no problems. The only thing I’m doing different this time is turning necks BEFORE necking down ( turn them to .0125 to end up with .014). Left case is after 1st stage with .324 bushing in Redding die. Everything is fine. Right case is after second stage with .308 bushing. The neck is badly "hour glass" shaped, measuring .306 at the very top and .303 to .304 in the middle. Also it looks like the die didn’t go as far down the neck to where the shoulder will be formed to like the case on the left. What the heck am I doing wrong?
Coyotefurharvester
Silver $$ Contributor
Did you pull the die out of the press to change the bushing?
Don't mean for it to sound like a snide remark but don't turn the neck before sizing them down. It's that simple. If you never had a problem before I don't know why you would change what you're doing
I thought of that but I can’t figure out how that’s effecting things. I neck turned first so I could get a uniform thickness PAST where the neck/shoulder junction will be without risking cutting too far into the shoulder.
No. The die is at the exact same depth
Makes sense. Thank you
You realise the 300 (and 270) are shorter than the 7WSM so you would need to shorten a 7WSM die if you want it to get all the way down the neck. it's around 40 thou to remove.
Like you, I always turn the bulk off the neck at the parent stage and then just a light skim when necked down to 7mm from 300 as I find it far easier, much less stress and spring back fighting the turning mandrel. Also do this with 6.5x47 to 6x47 and .308 when forming smaller necked diameter cases from Lapua Palma brass.
The lot of Lapua 300WSM cases I have all formed a bell end like yours when run through the shortened 7WSM die but were fine when run over the expander mandrel for the final skim turn
Like you, I always turn the bulk off the neck at the parent stage and then just a light skim when necked down to 7mm from 300 as I find it far easier, much less stress and spring back fighting the turning mandrel. Also do this with 6.5x47 to 6x47 and .308 when forming smaller necked diameter cases from Lapua Palma brass.
The lot of Lapua 300WSM cases I have all formed a bell end like yours when run through the shortened 7WSM die but were fine when run over the expander mandrel for the final skim turn
Bushing dies only size 1/2 the length of the neck?
What exactly is your chamber a true 7 wsm or a 7x 300wsm? As Leeman posted the 7 wsm is longer base to shoulder then 300 and 270 wsm. So a regular 7 wsm die will never reach the shoulder of the other 2 brass cases. Leaving some of the neck wider as a false shoulder will help with fire forming to a longer case measurement.
It’s a saami spec 7wsm. The part of the neck that the die (bushing) didn’t reach will become part of the shoulder after forming (hydro forming this time). But it appears that the first stage of necking down reached to where the new shoulder will be (approximately.038” longer), and the final sizing with the .308 bushing didn’t even come close. Looks way better after running an expander mandrel through it but I never did that before. There seems to be a lot more spring back than previous batches of the same brass I’ve done. I annealed one as an experiment and it didn’t make any difference.
I keep away from most wildcat cartridges. They accomplish nothing and can be a pain in the ass. I do FF 6BRX .
That's right.
Seems like you're just sizing too much with the last increment.
JSH
Gold $$ Contributor
Yes sir. I found this out with my 22BR. Ran the brass over a mandrel, then turned. I went to a minimum clearance, 3rd firing I saw some pressure signs. Fortunately it was still set up, I found some high spots.
Imho the OP is out of sequence so to speak, and it reared its ugly head.
Necking up or down can have it’s consequences.
I necked some brass up years ago, trimmed it all to length. When I got done there still was not a square mouth in the bunch.
Once one gets done “moving” things around is the time to do a next step
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