Neck turning question how much is enough, is enough too much?

[LRPV]

These questions are in regard to a 6-284 using 6.5-284 Lapua brass necked down.
Chamber neck is .276
Fired necks are .275
Loaded necks .274 (before any turning)
sized necks .272

I guess my question is how far can I go down before I start creating a bigger problem on the other end as far as having to size the neck back down too far and causing more of a problem instead of curing. And is turning only, say 50% of the neck just wasting time? As currently set up I am not moving the brass very much which should be good to go, but I think I did a terrible job when I initially sized the necks down.
I turned a few cases just to see what I had to work with. In order to completely clean up the necks I am left with about .271 loaded neck or .003 turned off. I tried turning a few to leave me with a .273 loaded neck but this only cleaned up about half the neck, or one side of the neck and never touched the other side.

With 100% clean up I would be at:
.276 chamber neck
.275 fired neck
.271 loaded neck
.269 sized neck
.275-.269= .006" to size the necks back down to load again, is that considered excessive?
Thanks Jason

 

[tenring]

You need to measure the distance between the chamber neck (.276) and the loaded neck (.274). At this point, you have .002" total clearance, or .001" per side. That is just about the minimum necessary. You could increase that distance a few more thous, but for a competion round, I would not do that.

Necks should be turned down to the neck-shoulder junction, and even just a tad (about .0001") further.

 

[artbosco]

You need to measure the distance between the chamber neck (.276) and the loaded neck (.274). At this point, you have .002" total clearance, or .001" per side. That is just about the minimum necessary. You could increase that distance a few more thous, but for a competition round, I would not do that.

Necks should be turned down to the neck-shoulder junction, and even just a tad (about .0001") further.

I totally agree with your first paragraph. And by the way, .002" total clearance is working its way up to the norm in short-range benchrest too. It used to be .001" to .0015" total clearance. However, turning down past the neck shoulder junction 1/10,000th is mighty hard to see and I'm not sure how you'd measure it, so I go to 1/32nd of an inch past the neck-shoulder junction.

 

[artbosco]

These questions are in regard to a 6-284 using 6.5-284 Lapua brass necked down.
Chamber neck is .276
Fired necks are .275
Loaded necks .274 (before any turning)
sized necks .272

If your loaded round is .274" [before any turning] in a chamber that's measuring .276", I think you stumbled into a piece of cake.

You've got in my humble opinion, what I wish I had, .002" total clearance without having to turn at all !!!

Count your blessings. Lapua has provided you with outstanding and consistent brass that doesn't have to be turned.

Just make sure you measure your loaded rounds to ensure the consistency is ongoing and constant.

 

[Erik Cortina]

The problem with your .002" clearance is that you are getting very close to the limit, and since you are not turning, some brass might be thicker the other and you might run into problems.

I would turn down to .272", that will allow you to clean up almost the whole neck and give you enough clearance so you don't have to worry about it. You will not be working your brass too much.

I run .004" clearance on my F-Class rifles.

P.S. To get from .274" to .271" you are not turning .003" off, you are turning .0015" off on each side. It's the same but different! ;D

 

[lpreddick]

the often overlooked benefit of neck turning is the thickness of the neck will be the same from tip to shoulder, the part of the neck just beyond the shoulder being the thickest. unturned necks ,after bushing sized grip the bullet tighter at the base of the neck as opposed to the tip. one can feel this difference while slowly seating the bullet. [/quote] if i can see you, i can touch you. BANG!

 

[bozo699]

Jason,
I agree with Outdoorsman, 1/32 is the standard and it is what I try to achieve when turning, from your other thread I know what your trying to do and if you just lightly clean your necks up you might achieve what your looking for, you can always turn more but VERY VERY difficult to put brass back on neck, with that being said turn for a approximately 70% cleanup, probably about a .001 total will achieve that and you will still be in torrence for total neck/chamber clearance.
Wayne.

 

[Steve Blair]

I concur with Erik on the clearance issue. Although I run .0025 diametral clearance in 6BR and .003 in 6mm Remington, I use .004 on larger calibers like .284 and .308.

Outdoorsman also has it right regarding the "shoulder cut" when neck turning. It is worth noting that Lapua brass has thick shoulders and is reasonably tolerant in this regard.

 

[LRPV]

Ok, everybody. I am (and was always) turning the necks all the way down into the shoulder. What I meant by only trimming half of the neck is that all the brass that is getting trimmed is coming off of one side of the neck. Meaning that for some reason my necks are very lop sided. Using K and M tools to do this with.

What I had planned on doing was just skimming the necks at the mouth and getting rid of the bulge at the shoulder but like stated above I am only cutting off one side of the neck. The good news (if there is any) that I will use a different procedure next time for sizing these down.

Bozo, yes it seems to be helping the concentricity even with just cleaning them a total of .001"

Thank you all for the comments.
Jason

 

[bozo699]

Ok, everybody. I am (and was always) turning the necks all the way down into the shoulder. What I meant by only trimming half of the neck is that all the brass that is getting trimmed is coming off of one side of the neck. Meaning that for some reason my necks are very lop sided. Using K and M tools to do this with.

What I had planned on doing was just skimming the necks at the mouth and getting rid of the bulge at the shoulder but like stated above I am only cutting off one side of the neck. The good news (if there is any) that I will use a different procedure next time for sizing these down.

Bozo, yes it seems to be helping the concentricity even with just cleaning them a total of .001"

Thank you all for the comments.
Jason

Jason,
I knew exactly what you were talking about, I just agreed with outdoorsman that going past the neck shoulder junction by 1/32" was important and the right amount needed. I was sure .001-.0015 would do what you were looking to do, I would venture to say .0025-.003 would totally clean the necks but I don't believe that will be needed for your goals, just a light cleanup 50%-70% should be just fine, I personally believe you have a perfect neck/chamber clearance right now and would hate to see you taking to much and have your brass stretch more then necessary not to mention your ultimiate goal to reduce run out and the more you have to size your brass back the more induced run out you can see, let us know after you have some done and you have shot them and reloaded them a second time how things are looking to you.
Wayne.

 

[LRPV]

Not much change in run out from neck turning and then sizing back to be loaded. Checked run out after turning and recorded results and then checked again after sizing back down. Some got better some got worse. All of them still running .001-.002 out. I'll see how they do after firing and sizing again. Can't help but think they will have to better next time around.
Jason