New Brass Prep, a newbie question

[GarethMarijt]

Hi,

I have bought new a new rifle (in 6mm BR, a new for me, calibre) and will be getting new brass for it. My rather newbie question relates to case preparation...

I am wanting to go for bushing dies, but won't know yet which bullets I will settle for, so I don't want to get the bushings just yet. Can I do the initial prep on the cases using an expander die followed by something like a Redding Body Die?

Thanking you in advance for your advice
Gareth

 

[fdshuster]

Gareth: My procedure for new chamberings is to have a supply of new Lapua brass for the new chambering ( I don't believe in using "old" brass with a new barrel), and when I get the rifle back from the 'smith, I will load one basic round. Powder charge well below max., bullet seated to touch. After firing, that case will get the spent primer hand punched out, cleaned, and I will take all critical dimensions, and they will be recorded in that rifle's log book. I keep a dedicated book for each chambering. Then I will decide on the bushing size I want to use, but will also have one .001" larger and one .002" smaller. Note: Check the actual sizing dia. of the bushing(s). They do not always size to the stamped ident diameter shown on the bushing. At this time the headspace length will be measured & recorded for adjustment of the Redding FL neck bushing die. Fired case neck dia. will also be verified, and normally it will be .001" smaller than the chamber neck dia., due to springback. Just my way of doing it. I'm sure there are others, but this works for me.

 

[artbosco]

I am wanting to go for bushing dies, but won't know yet which bullets I will settle for, so I don't want to get the bushings just yet. Can I do the initial prep on the cases using an expander die followed by something like a Redding Body Die?

Leave bushings out of the Redding Type-S Full Length Bushing Die, and in substance, you have a Body Die ... don't you?

Think about it for a moment. Without the bushing, you're only making adjustments to the body of the case, not the neck, because there is no bushing present to squeeze down or compress the case neck. There's nothing in the die's neck area but a large void.

No need for a separate body die ever.

 

[RonAKA]

I was in exactly the same situation, and here is how I went about it. It sounds as if you bought a factory gun? Assuming so, then the neck size is the neck size, and you can't do much about that. If it is a Savage then it is probably right around 0.272". The next most critical dimension is the neck size of a loaded round. To get that you should seat about 10 rounds and measure them all. Take the smallest you measured and subtract 0.002" from it. For bench rest single shot shooting that will give you 0.001" tension after springback which should be fine. For a magazine gun you would subtract 0.003 to get 0.002" tension.

For the older Lapua brass which came in a cardboard box, the neck tends to measure 0.269 minimum, so a .267" die is what you need for bench shooting. That is what I use. The newer Lapua brass in the blue plastic box has slightly thinner brass, and I don't have first hand experience to help you there, but if you do a search here you should find lots of info with "blue box". The require die is likely .266 or .265 for the new stuff based on what I see posted.

I would look seriously at the Forster Bushing/Bump die instead of the Redding. As I understand the story the Forster was previously Bonanza, and Bonanza had the patent on that style of die. When the patent ran out, Redding started making a knock off. Based on user reports here Forster seem to make their bushing a more consistent size. The ones I have are the size they are marked. The Ultra Micrometer seater die works very well too. I'm quite happy with it. You will also probably find Forster is less expensive than Redding, which is a bonus. Here is a history/testimonial for the Bonanza/Forester dies.

Bonanza/Forester Dies

So far all I have needed is to bump the shoulder 0.001" back (and you can use the die to measure that), and neck size about 2/3 of the neck. I may eventually have to FL size but no hint of a need after 5 firings. Also looks like they will probably go 10 firings or more before the case length needs to be trimmed.

 

[1000yardstare]

There is an excellent article on new brass prep from "Precision Shooting" that might help you out.

http://www.6mmbr.com/jgcaseprep.html

 

[GarethMarijt]

Apologies for the delay in getting back to you.

Thank you all very much for your sage advice, you have given me plenty to think about. By the way Ron, you were spot on, it is a Savage. I have taken your advice and bought the Forster set. I'll load some up, measure and then get the bushing die to go with it.

On one of the other posts, the rep from Lapua USA advised that you should only need to run an expander die to straighten any dings from transit, but I would feel cheated if I didn't do all the rest of the stuff as well .

Kind regards
Gareth

 

[RonAKA]

On one of the other posts, the rep from Lapua USA advised that you should only need to run an expander die to straighten any dings from transit, but I would feel cheated if I didn't do all the rest of the stuff as well .

On my new brass I found the necks were a little tight right out of the box. I used an Oversized Forster Expander Ball of 0.2430". Standard balls I believe are smaller than that by 1-2 thou. I found it opened the necks up about 0.001". Rightly or wrongly I have continued to use it. With the fired cases resized with the .267 bushing it just kisses the inside of the neck and opens them up about 0.0003". Not sure if that helps or hurts. I need to do some testing both ways to see.

 

[HolyMeekrob]

I've seen a couple people mentioning allowing for spring back. I just wanted to point out that I have witnessed zero spring back with my bushings. Every time I measure the neck after putting it through my .243 bushing it measures precisely .243. So I'm thinking that, at least with redding bushings, the .243 bushing actually has an internal diameter of .242 so that the spring back is already taken into account.

 

[RonAKA]

The Forster method is certainly to make the bushing the size it says it is. They give you a simple calculation to allow for spring back and desired tension. Perhaps Redding tries to do it for you. Have you tried to measure the bushings to see what size they really are?

 

[HolyMeekrob]

I have, but every time I take a measurement I always get a measurement of approximately .2425, so there's enough play that I can't be certain. Probably because I'm using a tubing micrometer and standard .001 calipers. I would probably need a blade micrometer to be sure.

 

[fdshuster]

HolyMeekrob: I'm thinking springback is caused by the firing of the cartridge. The case walls are slammed out, in all directions hitting the limits of the chamber, and springback occurs, usually at or very close to .001", depending on the age and hardening of the brass. When running the case neck into a bushing die, no firing is involved, no violent slamming and bounceback, so whatever the bushing I.D. is, that's also what the sized neck diameter will be. I know with my chamberings that were cut with my reamers, the as fired case neck diameters are all .001" smaller than the chamber neck diameter as shown on the reamers and reamer drawings. .272" chamber neck = .271" fired case neck dia. for example.

 

[whiskey08]

I would keep reading and develop an order and routine. I always neck size before body die because neck sizing stretches the length of the case. So after I neck size I go thru with a body die and set all the shoulders exact. Once the shoulders are the same then Ill trim if needed.

 

[spclark]

I'm thinking springback is caused by the firing of the cartridge. (snip) When running the case neck into a bushing die, no firing is involved, no violent slamming and bounceback, so whatever the bushing I.D. is, that's also what the sized neck diameter will be.

In theory that may be the case. In my experience springback works both ways, no matter the speed or degree of force involved. What originally prompted me to get into case annealing was the lack of consistent sizing taking place on fired cases.

For one particular 6mm cartridge as well as my Palma brass I found one die setting and bushing size would produce significantly variable shoulder bump and neck ID until I got around to learning how to safely anneal fired cases. Once I started annealing shoulders and neck (to look like what comes from Lapua as new brass) my sizing results became much more consistent.

I attributed the difference to the degree at which brass becomes work hardened even from one firing / resize cycle & that individual cases may take on more or less hardening than their siblings. Careful annealing removes the variations, returning brass to a more uniform state of hardness & thus making sizing die settings more reliable.

 

[HolyMeekrob]

HolyMeekrob: I'm thinking springback is caused by the firing of the cartridge. The case walls are slammed out, in all directions hitting the limits of the chamber, and springback occurs, usually at or very close to .001", depending on the age and hardening of the brass.

My understanding is that spring still occurs even in regular sizing operations but I can't say for sure, the metallurgy of shooting and reloading is one area that I haven't looked into much. However I've played around with sizing equipment and noticed that cases that have been sized don't readily slide back into the die or bushing or over the mandrel unless it was an over-annealed case (I played around with some when I was first started dabbling in annealing). Also I think there's evidence for spring back in regular sizing operations in that sinclair and I believe K&M make their sizing mandrels .001 larger than their turner mandrels.
I view spring back much like quantum mechanics. I can't see it or touch it or really understand it. But most people agree that it's correct and as long as it continues to yield predictable results, I'll continue to use it.
Yes, I just referenced quantum mechanics. Yes, I'm a nerd.