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Neck turning question - Question on Lapua brass

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MarkInPA

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Jul 8, 2024
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Location
Mifflinburg, PA
I'm asking this question with no experience neck turning brass. I'm considering adding this step to my brass prep. I just set up my Forster trimer for neck turning and was experimenting on brass I pulled with nonconcentric necks and variable neck thicknesses. I set up the turner to just skim off the high spots with maybe 1/4 of the neck left untouched. Does this seem like the right approach if all I want to do is concentric necks with equal neck thicknesses? I set the turner to turn the necks 1/16" short of the neck and shoulder junction. Is this the correct procedure? I have concerns about where the cutter stops short of the neck and shoulder junction. This is going to leave a sharp step from the trimmed to the untrimmed portion of the brass. To me, this doesn't seem to be good but, I don't know how to avoid it. Curious on your thoughts about this.

Also, I just purchased some Lapua brass. This is first for me. Just looking at it, the brass seems to be top notch. I'm not sure how to approach the case prep on this stuff. I'm almost afraid to touch it in fear I will only make it worse rather than improve it. I normally uniform primer pockets, debur flash holes, anneal and maybe now I might turn necks. Of course, I also chamfer and debur. I'm just not sure which of these operations I want to perform on this pristine Lapua brass. What are your thoughts?
 
For your non-Lapua brass: In order to have a true concentric surface you have to take the necks down so all the "scale" is removed. In order to prevent that definite step you can turn up the neck shoulder junction just a bit. 8th inch is pretty aggressive, 16th inch is usual. This makes the turning flow nicely and reduces the potential of a breaking point abrupt metal thickness changes can do.

You don't have to do much at all with Lapua brass. I always size the necks of the new brass to maintain desired "neck tension" (Interference fit) then chamfer for bullet seating ease. Flash holes are drilled, not stamped, so no need for flash hole uniforming. Most don't turn the necks either. I only turn Lapua brass when I size from 308 to 708 to ensure some chamber neck clearance for safety. If it weren't for that I never would turn.
 
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I neck turn Lapua 30-06 brass to .0015 after necking down to 6.5-06. Otherwise necks are too thick and don't have room for expansion when fired. There will be a small step down from the neck shoulder junction to the turned portion. I get very good accuracy with these loaded and any sign of that step is gone after the first firing.
 
IMO might as well do a 100% percent clean up since you're already doing the work. but a skim turn is fine also. If your cutter matches the shoulder angle then by all means cut into the shoulder a little. It helps mitigate brass flow and possibly donuts.

1732551934389.jpeg
 
MarkInPA said:
I'm asking this question with no experience neck turning brass. I'm considering adding this step to my brass prep. I just set up my Forster trimer for neck turning and was experimenting on brass I pulled with nonconcentric necks and variable neck thicknesses. I set up the turner to just skim off the high spots with maybe 1/4 of the neck left untouched. Does this seem like the right approach if all I want to do is concentric necks with equal neck thicknesses? I set the turner to turn the necks 1/16" short of the neck and shoulder junction. Is this the correct procedure? I have concerns about where the cutter stops short of the neck and shoulder junction. This is going to leave a sharp step from the trimmed to the untrimmed portion of the brass. To me, this doesn't seem to be good but, I don't know how to avoid it. Curious on your thoughts about this.

Also, I just purchased some Lapua brass. This is first for me. Just looking at it, the brass seems to be top notch. I'm not sure how to approach the case prep on this stuff. I'm almost afraid to touch it in fear I will only make it worse rather than improve it. I normally uniform primer pockets, debur flash holes, anneal and maybe now I might turn necks. Of course, I also chamfer and debur. I'm just not sure which of these operations I want to perform on this pristine Lapua brass. What are your thoughts?
Click to expand...
 
For hunting rifles with normal SAAMI chambers and Lapua Brass I'd say the juice is not worth the squeeze. It's really hard to improve the performance of Lapua brass which IMHO is the best brass money can buy. It wont turn a 1 minute rifle into a 1/4 minute.
On the other hand if you are shooting bench rest or F-Class every little bit helps so everyone neck turns.
 
Beluebow said:
IMO might as well do a 100% percent clean up since you're already doing the work. but a skim turn is fine also. If your cutter matches the shoulder angle then by all means cut into the shoulder a little. It helps mitigate brass flow and possibly donuts.

View attachment 619435
Click to expand...
What turner do you use? Look amazing!!
 
Beluebow said:
IMO might as well do a 100% percent clean up since you're already doing the work. but a skim turn is fine also. If your cutter matches the shoulder angle then by all means cut into the shoulder a little. It helps mitigate brass flow and possibly donuts.

View attachment 619435
Click to expand...
A few good points here ^^^.
The cutter angle should match your shoulder angle
It is a good idea to turn the entire neck far enough that you touch the shoulder as seen above
* I might add that some benchrest shooters stopped turning brass a long time ago. If you use high quality brass and have a chamber that fits the brass reasonably well, you may see no benefit to turning case necks. Personally, I order "no neck turn" chambers on all of my new barrels and provide the gunsmith with my brass in advance.

Turning necks is a PITA. Why bother if there isn't a tangible benefit?
 
Varmint Hunter said:
A few good points here ^^^.
The cutter angle should match your shoulder angle
It is a good idea to turn the entire neck far enough that you touch the shoulder as seen above
* I might add that some benchrest shooters stopped turning brass a long time ago. If you use high quality brass and have a chamber that fits the brass reasonably well, you may see no benefit to turning case necks. Personally, I order "no neck turn" chambers on all of my new barrels and provide the gunsmith with my brass in advance.

Turning necks is a PITA. Why bother if there isn't a tangible benefit?
Click to expand...
Am I going down a rabbit hole here with no returns? I'm not using this ammo in competition but rather in production made rifles for hunting. I do like to have very accurate ammo and will do what I can to make it as accurate as possible. I wasn't considering neck turning because of tight chambers in competition rifles. I was only seeking concentric brass and an equal amount of grab on the bullet all the way around. Was also hoping to reduce run out. I was thinking that the concentric brass would be more true coming out of the sizing dies. Especially if you were using bushing dies.
 
MarkInPA said:
Am I going down a rabbit hole here with no returns? I'm not using this ammo in competition but rather in production made rifles for hunting. I do like to have very accurate ammo and will do what I can to make it as accurate as possible. I wasn't considering neck turning because of tight chambers in competition rifles. I was only seeking concentric brass and an equal amount of grab on the bullet all the way around. Was also hoping to reduce run out. I was thinking that the concentric brass would be more true coming out of the sizing dies. Especially if you were using bushing dies.
Click to expand...
Mark,

If your other equipment is fairly expensive, I see neck turning as just another step towards consistency. Use it when needed.
I upgraded my equipment a few years ago and moved from 1.0 MOA to .5 MOA over several rifles with a better powder measure, annealing & neck turning equipment upgrades.
 

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