I've lately be necking down Lapua 308 Winchester brass to form 7mm-08 remington, and now seem to have a tight neck situation due to the extra brass increasing the thickness of the neck.
The 7mm-08 Federal and Winchester brass I've used in the past of a loaded round tends to measure around .3110", but the neck sized down Lapua brass of a loaded round measures .3150"-.3155". Which according to SAAMI is at the case neck dimensions of the case (.3150"), the chamber dimension is .3170" at the neck shoulder juncture and .3160" at the end of the chamber. Which in this case is rather tight for neck expansion to release the bullet upon firing. These loads with unturned brass have also not produced the same bug holes as the previous loads with the other brass leaving me to think I'll need to turn down the necks.
Wow..... I would never like to neck turn another piece of brass in my life again! Pain in the butt, sore palm as well from holding onto the case holder tightening and doing the neck turning its self.
Neck up if at all possible. No need to neck turn since the brass neck will thin during the process.
If you neck down, I hope you have a factory chamber and not something cut like a match chamber or you might be doing a ton of work for very little gain. I found the best way with the end result being better is to turn the case first, then neck down. Or make it even easier on yourself and just inside neck ream the darn case.
The factory new parent case will have perfect parallel sides on the neck after running it over the mandrel. Which will prevent any excess brass from being removed that is not fully sized in the die at the neck shoulder juncture if you've already sized down.
If by chance the case as been already fire formed, then turning after will also produce a more concentric neck then if it wasn't fire form first.
I use at least a 6x magnifying glass to check the progress of the neck turning. If you turn a new unfired unsized parent case and turn the neck "to" the shoulder, you'll see that after sizing down the turned portion will become part of the new neck formed, and it will look uniform. vs. if you turn a neck down case, you will need to cut just to the point that the cutter puts a beveled edge on the shoulder. But here the deal, you'll notice when the cutter is 4/5 of the way down the neck it will start to remove more material with each turn then the rest of the neck or if done on a factory parent case or a fire formed case. That's because during the necking down in the sizing die the brass has moved to not only make the neck thicker but more brass moved into the neck shoulder juncture that the sizing die made... the "dreaded donut" and/or a false shoulder will appear. Which is why you'll need to neck turn all the way to the neck shoulder juncture. You'll also need to resize again after turning the neck, where the sizing button will iron out the donut to the out side of the neck. Which you'll avoid doing that twice if you neck turn the parent case first, or a neck reamer can be used to remove the donut/and or the neck thickness of the parent case in the first place if you'd like to forgo the neck turning altogether!
Either way avoid the hassle and buy properly head stamped brass and enjoy all that extra time shooting, hunting or watching TV for that matter. Me I still have 325 pieces of brass to do...... so I bought myself some nice gloves with blister armor in the palm so I can maybe actually finish this job I wish I didn't have to do!
"Only accurate rifle are interesting" Col. Townsend Whelen
Last edited by longrangehunterII; 01-27-2014 at 03:17 PM.
Reason: Spelling error
Are you not be using a battery powered drill to turn the brass for the outside neck turning?
Which brand outside neck turning tool are you using?
No I'm not, turning them all by hand using a K&M Neck Turner Kit. At first I was using Imperial Dry Neck Lube inside the necks, well it wasn't enough to handle the friction, so I which to using Imperial sizing die wax instead and the issues went away making my life much easier!
The real issue was locking the case into the case holder that caused a lot of the pain in my right hand (the one I use to hold the case holder in). I now use a wrench, which helps. Most of this is just a learning curve...... but I'm not a fan of turning necks either way, but in this case I had to.
"Only accurate rifle are interesting" Col. Townsend Whelen
Yikes! I use K&M neck turning tools, but I use a battery powered drill. You can purchase tool attachments that will hold the cartridge case head securely. Then chuck the tool into the drill and turn away. Let the battery powered drill do the turning. It's not a terrible chore at all then. Plus you'll get a better end product. You're needlessly suffering self-abuse.
Imperial Case Wax is a pretty good lube for inside case necks and the neck turning mandrels. I use it also.
i think it would be a good time for somebody to start a threat on how well there groups are before this and just how much better there group sizes are after this
skim coat neck turning .
I neck turned my .243 in a factory rifle and it consistently shrank groups about 0.2" or so depending on the bullet. One bullet I couldn't get to group under 1.25" until I neck turned the cases. I shoot Winchester brass. I did it to have more even neck tension.
The most direct answer to "why are you neck turning all your brass in the 1st place" might be to achieve uniform neck wall thickness. With that as the objective, it really doesn't matter whether you first "fire form" the necks or turn new brass. .001 is 001 on a new case or fired case; the case doesn't know when it was removed and once the uniform neck wall thickness is achieved the next objective would be to establish a desirable overall neck tension on the bullet.
I typically turn necks by determining where the thickest part of the neck is, using that as a zero point, and turning until the neck wall is uniform. Then I fire the case. (I see no reason to use a weak load/cream of wheat concoction. I just get a little trigger time having fun punching holes in targets)
Next I slightly resize the case (so that it is just under neck expander dimensions) and run the neck expander through it to round everything out. The fired case tells me (within reason) what the chamber looks like; the wall thickness consistency tells me that if I turn off any more of the neck it will remain consistent overall; so all I have to do is a little math to come up with neck wall to chamber wall clearance and neck tension and select a neck resizing bushing to meet my needs.
I think it's always a good idea to remain mindful that working the brass tends to harden it so an annealing schedule can help a lot to lengthen brass useful life.
I have a great woman, fantastic kids, a warm place to sleep and an accurate rifle. Life is good ..............
Hunter Safety Instructor - California Hunter Safety Meritorious Service 1971 - 1972. Rifle/Pistol Marksmanship Instructor - NRA Life Member
American rifleman's triad - God, guts and guns. It built America and it'll preserve America. Abandon one and you lose them all.