Is there a guideline for the thinest you can safely go in turning brass in thousands of an inch? For example if your brass necks are .015, is there a number say .012 that you should not go thinner?
Brass case neck wall thickness
- Thread starter Eddie Vializ
- Start date
madmixerman
Gold $$ Contributor
It depends on the diameter of the neck in your chamber. I have have some brass turned to .0088 for my .262 necked br. and another turned to .0115 for my .266 necked dasher.
I'm not looking for "how much should I take off" but is there a generally accepted minimum neck thickness considered safe and not shorten the life of the brass. Your numbers give me a good indication of what I'm looking for. Thanks much. : )
What madmixerman is stating is correct. However, I understand your question too. Whenever I buy a reamer, I make sure that I turn the necks to 3 / 4 thousandths chamber wall clearance, 4K being better for a 7mm in my opinion. The "number" I use as a rule is a neck wall thickness of 12 Thousandths. 12K, if you anneal often, makes for VERY smooth bullet seating and I never have any "neck" issues whatsoever... So ALL my necks are turned to 12K... But this is what works for me>>>>that certainly is NOT a hard fast rule..
.012" is fine to use as a minimum. I have also heard it said that "plus zero, minus eight" meaning whatever the SAAMI outside dimension is minus .008"
All that said, too much neck clearance might not help your accuracy. This is why with a standard SAAMI chamber {e.g. a hunting rifle} they say to only just clean up or wisk off the high spots when you outside neck turn. You can certainly take it down to .012" and it will not present any danger, but it wont help your accuracy either...in fact having the neck flop around in the chamber might hurt accuracy. Many guys want to see the entire neck surface of the case clean completely up, so they turn it down to minimum.
Generally speaking, when someone is turning to a given dimension it is because they are matching a tighter necked chamber. I think it is a mistake to arbitrarily just thin the necks of brass cases not knowing what your chamber neck size is. Sometimes for some reason it don't hurt anything and that guy really thinks he is doing something...many times the rifle just wont quite group the way it should.
All that said, too much neck clearance might not help your accuracy. This is why with a standard SAAMI chamber {e.g. a hunting rifle} they say to only just clean up or wisk off the high spots when you outside neck turn. You can certainly take it down to .012" and it will not present any danger, but it wont help your accuracy either...in fact having the neck flop around in the chamber might hurt accuracy. Many guys want to see the entire neck surface of the case clean completely up, so they turn it down to minimum.
Generally speaking, when someone is turning to a given dimension it is because they are matching a tighter necked chamber. I think it is a mistake to arbitrarily just thin the necks of brass cases not knowing what your chamber neck size is. Sometimes for some reason it don't hurt anything and that guy really thinks he is doing something...many times the rifle just wont quite group the way it should.
All excellent info and exactly what I was looking for. My chamber is .314, a few loaded dummies using new 6.5x284 Lapua brass necked up to .284 win finish at .312 or just a hair over. The neck wall thickness averages .015 using a Mitutuyo outside ball mic. I understand the .284 likes .004 space for bullet release. (I take it .002 per side) So if I clean up the necks a thousand and a half or so........F-open look out! I'm off to the races!
If your measurements are true, you might start @ .0015" per side, if you want a simple number. It will give you slightly less than .004 clearance, but will not hurt your accuracy.
The true cut for exactly .004 clearance would be .00175". It is easier to turn, at least at first, to be safe. All your brass is going to have some variance. All my assumptions are based on your measurements. You can take it off, but you can't put it back.
Good luck with your adventure into neck turning.
The true cut for exactly .004 clearance would be .00175". It is easier to turn, at least at first, to be safe. All your brass is going to have some variance. All my assumptions are based on your measurements. You can take it off, but you can't put it back.
Good luck with your adventure into neck turning.
Upgrades & Donations
This Forum's expenses are primarily paid by member contributions. You can upgrade your Forum membership in seconds. Gold and Silver members get unlimited FREE classifieds for one year. Gold members can upload custom avatars.
Click Upgrade Membership Button ABOVE to get Gold or Silver Status.
You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.
To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.
Click Upgrade Membership Button ABOVE to get Gold or Silver Status.
You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.
To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.