Ammosmith Forums > Rifle Reloading

Neck Turning Inside and Out


Okay guys these topic has been driving me crazy. I know others have covered the topic of neck turning but I have a little more specific question. I have called places like Hornady and read online only to discover that there are so many ways people neck turn. I just want to know which method of these following works the best and would give you the most accuracy. Okay first this is if your using match dies and match grade bushing with your neck sizing. The first method I was told was to take a fired shell and, with using calipers, measure the diameter of the neck. Then do the same for one that has a bullet seated in it to. Minus the two and the difference equals the complete expansion. Then take shells you have necked turned, say to 12,000 of an inch. Multiply by two for the complete brass neck and add to the complete expansion you found before. Then you minus 3000 of an inch. This number is the proper neck bushing size you need for the right amount of neck tension and with 12,000 of an inch neck thickness.

Next method: just take a brass that has a bullet seated in it and measure, with calipers, the diameter and minus 5000 of an inch from it. This method, as far as I have read, is made for factory guns that you want a match grade bushing for but later I've heard that it could be used for match grade guns as well. This method seems the easiest but how accurate is it and after finding out the measurement of the bushing you need how do you know what you need to neck turn down to for it to work (because neck turning thickness dictates what match grade bushing you need).

Now these next methods involve just using standard neck sizing bushing:
First one I was told: measure, with calipers, the neck diameter of a brass that has either not been fired or one with a bullet seated into it and minus the bullet diameter from the complete diameter (not sure if this is right and how to find the bullet diameter unless you just take any normal bullet and measure it or if it's in a reloading book). Minus the two and If the difference between the two is greater than 4000's of an inch then it's fine but if it measures less than 4000 of an inch then you didn't have enough room for proper expansion and you must neck turn. I guess you would neck turn down so that you could have up to 4000 or 5000 of inch expansion without going under 11000 of an inch which would cause head and neck separation. The problem I have been told with this method is that brass has a certain amount of springback and this measurement won't always be that accurate to know when to neck turn.

next method with normal neck sizing die: I was told to use a reloading book and take the measurement given for the complete diameter. Minus the bullet diameter (again don't know if this is given or if you take any normal bullet and measure it). Then divide by 2 for the single side of the brass. This thickness is what the neck turning should be turned down to. Problem though is that I figured out that this measurement is the uttermost maximum you can have. So how far from this measurement should you neck turn down to or should a different method be taken.

LAST METHOD: this one is the most simple and actually is use in one or two already. Just take all your brass measure them with micrometers and then find the smallest average spot and neck turn them all down to that so that they are all uniformed and all the sides of the brass's neck get turned.

Now that those methods have been said I just wanted to ask about the inside of the neck case. I know that outside neck turning only has to occur once but that after some more neck turns the inside of the neck begins to thicken. My question is how do you cut the inside of the neck? Is it some type of reamer or actually a device that has more precision? If it's just a reamer then okay but if it's something that has a method of precision then how far down should it be neck turned on the inside of the neck especially without going below the 11000 of an inch thickness. Also what should the measurement be around when reading the ball micrometer? Should you just compare it to normal unfired cases? Thanks for all your help guys! I really need it on this one!!!

Alan 204.:
Keep it simple ?


Black Mamba:
This is a topic that will take a bit of time to explain, as I am getting ready for work now I can't answer the way I would like but will respond later. For the mean time, please tell us a bit about your rifle. Is it a factory rifle or is it a custom built match rifle?

Black Mamba:
To answer your question in the best manner I will need to know a little bit more about your setup. You listed a few methods and seeing as you are listing both standard dies and competition dies is it safe to assume that either you have neither or are you wondering if it is worth the purchase of competition dies? As you say, there are various ways to turn case necks. This is because it depends on the equipment you are using and what type of rifle is being used. Bullet diameters are a standard size from all of the major bullet manufacturers - for instance a 30-06 shoots a bullet that is .308" in diameter, a 7mm magnum uses a bullet .284" in diameter. This information you can obtain from a reloading manual. Neck thickness varies depending on the brass manufacturer and the lot. Because of the case drawing process the brass will not be uniform around the circumference of the case. To get a uniform release you can neck turn to get an even thickness. If you are reloading for a match rifle there are a few things you can do to make a cartridge last a while and to cut down on reloading time (as most match rifles are loaded at the range between shoots with light reloading equipment). If you are talking a factory rifle there is usually a bit of slop built into the neck portion of the chamber to allow factory ammo to work correctly in your rifle so the necks will expand too much to use the spring back of the brass to be used in your favor. If you are using a standard reloading die you want to clean up your case necks taking the least amount of material from the necks. If you cut them to thin you will either make them fail on first firing or you will lose neck tension because the die won't size the neck enough to hold the bullet. Bushing dies allow you to adjust the neck tension by choosing a smaller or larger bushing to squeeze the necks down and you don't use a sizing button with them so you want to cut the necks to an even thickness so you can adjust the tension accurately. As far as the donuts you are asking about (the thickening of the case at the neck/shoulder junction) They usually only form when you seat your bullet far enough out that it does not extend below this junction. Usually the seating of the bullet will swage the brass here before it begins to build up. You can buy tools to cut the donuts out if you find it necessary to do so. If you can provide us with more information on your rifle/dies/caliber I can walk you through how to turn the cases to get the most out of it and your equipment.

Black Mamba,

I have been wondering the same thing as fishblade recently. If you can give me a little info on it, that would be awesome!

I'm shooting a Savage BAS .308, Remmy 700 .204, and DPMS 5.56 (semi auto). I have RCBS dies for the 308 and 5.56 and some Lee Collet dies for the 204.

I have talked with a guy that I bought some equipment from, and he told me that the best way to do it is to make sure there is even neck tension, and just a little bit at that... What are your thoughts?

I am looking to get the Hornady trimmer off of, but I'm open to others if there are better recommendations... I know that Hornady has always treated me very good in the past, so I figured I would stick with them...


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