By Joseph D’Alessandro Editor | RealGuns.Com
Through neck size reduction, or brass flow under chamber pressure, material thickness at a case neck may increase. The result is an inside neck diameter that is not concentric to the outside, or a case neck outside diameter that is oversize to specification. These conditions may cause: a loss of accuracy, a loss of safety margin in chamber clearance or even a cartridge that won’t chamber. How do you know if it is time to turn case necks? Well, a good place to start is by following the procedures found in any good reloading manual within the sections defining case inspection and case prep. Basically, you measure neck wall thickness at a few points to check for concentricity and material thickness. You multiply this dimension by two, adjacent sides, add this dimension to bullet diameter and, if it is greater than spec, you neck turn.
In my situation, and being the slick tech guy I am, I formed 17-357 RG from 357 SIG brass, which of course increased material thickness, then seated a bullet, and discover the cartridge case would no longer chamber. Subtle clues are not always lost on me.
There are essentially two types of outside turners; lathe, based on a lathe type case trimmer, and handheld, based on…a pencil sharpener….sort of. When I discovered the oversize neck condition on my 17-357 RG cases, I set up my trusty RCBS trimmer, with neck turning attachment in place, and discovered the fixed frame would not adjust down to reach, much less neck turn, the short wildcat’s 0.0865″ case. My Hornady trimmer can adjust for cartridge length on both cutter and holder ends, but there is no outside neck turner kit for this product. I was left with a couple of options; purchase another lathe type trimmer that was frame adjustable with a neck turning attachment, or purchase a handheld neck turning tool.
The RCBS unit does a great job of uniform outside neck turning in all situation other than this specialized cartridge, so I really didn’t want to spend $150 – $225 on another set up that would see limited use and mostly duplicate existing equipment. I started reviewing handheld neck turners, discarding the Hart neck turner as too expensive, and the Model 3000 Sinclair for the same reason; I couldn’t find any functional difference from the lower cost models. I was able to zero in on three models that sold in the mid $50 range, then cut this to two when I eliminated the Sinclair 1000; its micro cutter adjuster worked only in one direction which would make it awkward in use.
The Forster unit (photo right) had the most to offer; it was nicely made, had an anodized finish, two way micrometer cutter adjuster, and fit a wide range of cartridges from 17 through 60 caliber, including the 50 BMG. It was the least expensive of the three models, but it was also out of stock and I was out of time. I opted for the Hornady Neck Turning Tool as a close second choice. By specification and general design, the Hornady tool appeared to be functionally the same as the Forster model, with only slightly less capacity; mandrel sizes cover .172″ through .375″. Since the tool wasn’t intended to replace my RCBS unit, but only to fill a gap for the 17-357 RG, the upper range capacity limitation was not a concern. At $57 online, the Hornady unit was 5 bucks more than the $52 Forster.
Hornady Neck Turner – A Few basic components
The body of the Hornady tool is cast aluminum, functionally a good selection; light, smooth edges and not prone to corrosion or in need of much maintenance. On the other hand, it is less than exciting in feel and appearance where precision of effort is the intended result. The tool looks unfinished and in need of some nifty hard anodizing, metal replacing plastic thumb screw heads on the case holder, some reference index numbers on the cutter adjuster would be nice so the operator doesn’t get lost while making adjustments. A minor issue, the foam insert for the storage box is clearly for some other product, as the cutouts don’t even come close in matching the contents. Am I being petty? Maybe, but I don’t think it is consistent with typical Hornady quality which, in my experience, in generally excellent. Hornady typically does a great job of common component cost reduction in dies and tools, in a way that improves output – this is just sloppy and a tad disrespectful of customers.
The process
Neck turning begins by identifying a case neck diameter specification, typically found in a reloader’s manual. Next, actual case neck wall thickness is measured, multiplied by two to account for adjacent sides, and added to the diameter of the applicable bullet. If the measured material exceeds the specification, the neck must be turned to eliminate this difference. My 17-357 RG project example appears, left.
The formed 17-357 RG brass had a 0.020″ neck material thickness. Seating a 0.172″ bullet would expand the neck and result in an overall neck diameter of 0.212″. The spec for the 17-357 RG is 0.199″, or approximately 0.022″ less. To calculate correct material thickness, I subtracted the bullet’s 0.172″ diameter from 0.199″, and got 0.027″ for a total material thickness, then divided by 2 to arrive at neck wall thickness. Through turning, I would have to reduce the wall thickness to 0.0135″, or 0.013″ for simplicity sake, to meet spec and achieve sufficient clearance in the 0.206″ chamber; 0.007″ had to be removed from the newly formed 17-357 RG cases. Neck turning is actually very simple.
The cutter is backed out enough to clear the case neck, and the mandrel is adjusted in our out of the cutter head until the angle on the cutter intersects the neck and shoulder of the case. Then the mandrel jam nut is locked to prevent the mandrel from moving in use.
The lower photo without a case in place shows the mechanical details more clearly. The set screw forward of the cutter adjuster locks the cutter in place, once set. I’m not sure why, but the cutter itself is not a replaceable part and comes installed from the factory. Once the length of cut is set with mandrel adjustment, the cutter adjustment wheel is turned until the cutter barely contacts the case neck. Then the case is extracted from the mandrel and the cutter adjustment wheel is adjusted to set the depth of cut. In this case, the cut needed to be 0.007″, so 7 increments on the adjustment wheel.
This shot is probably a better illustration of metal coming off, and a half turned case. The case head is clamped in the case holder with as much remaining case projecting as possible. If the case is set too far into the holder, the turning arms of the holder will hit the adjustment wheel before the case cut is complete.
In reality, the cutter adjuster index marks do not track to 0.001″, it took approximately 12 increments to make a 0.007″ cut; a little trial and error was required, but nothing exceptional. Once set, it was easy to produced cases consistent from one case to the next with less than a 0.001″ variation and concentric. Because the cut is made by putting the cartridge brass between a mandrel and cutter, the case necks were uniform all the way around. The only time I got a dimensional flyer was when I pushed too hard, literally, and raised a ridge on the case neck. Application of steady, reasonable pressure eliminated the problem.
Summary
Setting aside superficial aesthetic issues, the Hornady Neck Turning Tool worked great. It is fast and precise and easy to use, and It holds adjustment. I don’t anticipate a lot use, mostly a one shot deal at the end of the new case forming process. If there is one complaint about function, it is the factory installed cutter. It will be a $57 replacement cost for what should be a $5 replaceable bit.
I heard from a person who frequents the site, mostly to extend sympathies for the arduous path the 17-357 RG project has taken. I really don’t mean to leave people with the impression this type of project isn’t fun. I just write so people can follow a long and get some details of the experience for their own reference. Ultimately, the work makes the effort rewarding and there is a great deal of satisfaction in solving problems and working around obstacles. At the time of this writing, the 17-357 RG had already made it’s initial trip to the range, the results were better than I anticipated and I should be able to post detailed ballistic and accuracy data next weekend. And if you snoozed through a portion of this, I completely understand.
Thanks,
Joe
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