Neck turning difficulty

1

10ring

Member
I'm having a little trouble when I turn the necks on some Lapua 220 Russian brass which has had the neck expanded up to 6mm. The turning Arbor starts into the neck with a slight amount of interferance, (which is good), but when the Arbor gets in far enough to be at the neck/shoulder junction it requires a lot of force to push it past this point.

Am I doing something wrong or missing a step?
 
Donut would be my guess. Might inside neck ream or I think there is a way to move the extra brass to the outside and turn it off. Hopefully Someone more experienced than me will address this.
 
Possible information

A couple of guys Mike Bryant and Dan Lilja have a few notes and pictures on Accurate Shooter @ "Neck Turning with lathe or mill."
Might contain info you can use.
Centerfire
 
uk5qQlY.jpg
 
more possibilities

Upon revisiting Accurate Shooter and putting in 'Neck Turning' a lot of information drops down. Number 4 is pretty good regarding the cutting angle of the tool used to get the correct removal of OD brass at the neck shoulder junction to eliminate reaming need.
Centerfire
 
Centerfire said:
Upon revisiting Accurate Shooter and putting in 'Neck Turning' a lot of information drops down. Number 4 is pretty good regarding the cutting angle of the tool used to get the correct removal of OD brass at the neck shoulder junction to eliminate reaming need.
Centerfire
Click to expand...

My problem is getting the turning arbor in far enough to get the cutter into the brass.
 
You need to expand up a thou more or find a mandrel 1 thou smaller. You don' want the brass to tight or everything gets to hot and it starts to change all your dimensions through expansion.
John
 
Has anyone tried an inside reamer on the 220 Russian case that has had the neck expanded? If I were to do this I would have to get a case holder for the 220 Russian case, i think.
 
John VM said:
You need to expand up a thou more or find a mandrel 1 thou smaller. You don' want the brass to tight or everything gets to hot and it starts to change all your dimensions through expansion.
John
Click to expand...

If I do this I'm afraid the arbor would be loose on 80%% of the neck and then a slight interference fit over the last 20%. (Those percentages are guesses on my part)
 
""My problem is getting the turning arbor in far enough to get the cutter into the brass.""


If you're at 0.243 then you expand with a 0.242 mandrel and turn with a 0.241 Even with a carbide mandrel I find it useful to lube the case neck and I prefer resizing wax.
 
Last edited:
What neck turner/system are you using?

Are you using a "matched" expanding mandrel, prior to turning?

The K&M system offers a carbide turning mandrel that also incorporates internal cutting flutes, that eliminate "donuts".

Note.....I inspect each turned case, to insure that my set-up is actually producing necks that are within 0.0001" T.I.R.

Hope this helps.

Kevin
 
10ring said:
I'm having a little trouble when I turn the necks on some Lapua 220 Russian brass which has had the neck expanded up to 6mm. The turning Arbor starts into the neck with a slight amount of interferance, (which is good), but when the Arbor gets in far enough to be at the neck/shoulder junction it requires a lot of force to push it past this point.

Am I doing something wrong or missing a step?
Click to expand...

After expanding, the lower portion of the neck is what used to be the upper shoulder area. Consequently, the I.D. of the lower portion of your newly expanded neck is going to be smaller than the I.D. of the upper part of the neck.

You can call it a 'donut' or a 'funnel' shape to the inside neck. Regardless, a perfectly round turning mandrel will never fit well.

I make the inside of the necks perfectly round and straight before turning.

Good shootin' -Al
 
Al Nyhus said:
After expanding, the lower portion of the neck is what used to be the upper shoulder area. Consequently, the I.D. of the lower portion of your newly expanded neck is going to be smaller than the I.D. of the upper part of the neck.

You can call it a 'donut' or a 'funnel' shape to the inside neck. Regardless, a perfectly round turning mandrel will never fit well.

I make the inside of the necks perfectly round and straight before turning.

Good shootin' -Al
Click to expand...

How do you do that, Al?
 
Kevin Gullette said:
Are you using a "matched" expanding mandrel, prior to turning?

The K&M system offers a carbide turning mandrel that also incorporates internal cutting flutes, that eliminate "donuts".

Note.....I inspect each turned case, to insure that my set-up is actually producing necks that are within 0.0001" T.I.R.

Hope this helps.

Kevin
Click to expand...

That sounds like something that would work. I didn't realize anyone made something like that. Looks like they're called a "Carbide Cutting Pilot" at $54 each.
 
10ring said:
How do you do that, Al?
Click to expand...

My system is very much like this one pictured in Tony Boyer's book. I had Wilson make up reamers in .0005 increments. A lathe made steel bushing aligns and supports the reamer in the holder.

6jl460tl.jpg
 
Last edited:
10ring said:
@Al Nyhus - was the case holder for the 220 Russian case?
Click to expand...

If you're using a Wilson trimmer, you'll want a case holder for the 220R for the cases prior to them being f-formed. Then you'll need the case holder for the PPC family for trimming.

With the Wilson setup, not only do you make the neck I.D.'s round and straight with the neck reamer.....the neck reamer then does double duty for addressing any donuts that may develop on your f-formed cases during their life span.

Be aware that the 'standard' Wilson neck reamers for calibers are typically .0025-.003 larger than the bullet diameter. For a 6mm bullet, the 'standard' neck reamer is .2455-.2460, for example. Wilson will make any size reamer you want so you can measure your expander mandrel and your turning mandrel and order the size that works for your situation.

You can also do this with a standard chucking reamer of the size you decide on. You can make a bushing to fit the trimmer and whip up a small knob to rotate the chucking reamer with. That's what the previous picture shows being used.

Hope this helps. -Al

https://lewilson.com/inside-neck-reamer
 
Al Nyhus said:
If you're using a Wilson trimmer, you'll want a case holder for the 220R for the cases prior to them being f-formed. Then you'll need the case holder for the PPC family for trimming.

With the Wilson setup, not only do you make the neck I.D.'s round and straight with the neck reamer.....the neck reamer then does double duty for addressing any donuts that may develop on your f-formed cases during their life span.

Be aware that the 'standard' Wilson neck reamers for calibers are typically .0025-.003 larger than the bullet diameter. For a 6mm bullet, the 'standard' neck reamer is .2455-.2460, for example. Wilson will make any size reamer you want so you can measure your expander mandrel and your turning mandrel and order the size that works for your situation.

You can also do this with a standard chucking reamer of the size you decide on. You can make a bushing to fit the trimmer and whip up a small knob to rotate the chucking reamer with. That's what the previous picture shows being used.

Hope this helps. -Al

https://lewilson.com/inside-neck-reamer
Click to expand...

Yep, that helps. Thanks! -- Todd
 
You must log in or register to reply here.
Back
Top