Home Forums Reloading Big Game Rifles Question on neck thickness measuring tools

Continued from "Mr. Barsness convinced me".
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<br>I was measuring case neck thickness with my new RCBS Case Master and it was proving pretty frustrating. The case neck is placed on a little pin and a sliding sleeve rests lightly on top of it with the dial indicator registering on the top of the sliding sleeve. The problem is the whole weight of the case is hanging out in mid-air and only held in place by the VERY light tension of the dial indicator pin. This makes my heavy .300 Mag cases seem terribly inconsistent while a few .223 cases I tried seem very consistent. I could change the readings for any case three or four thousandths just by moving the case back and forth horizontally a wee bit, and I would get different readings at the same point on the neck depending on my technique of twirling the case around the pin, i.e. terrible repeatability.
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<br>So - what is the MOST CONSISTENT, ACCURATE AND REPEATABLE tool out there for measuring case neck thickness? Note the emphasis on CONSISTENCY and ACCURACY, I did not specify fast. This operation need only be done once and I'd only be measuring 50 to 100 cases at any one sitting anyway.
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<br>Mtn Hunter in another thread recommended the Sinclair Neck Thickness gauge, but I see that it uses RCBS deburring tool stops and again, the case looks to be hanging out in midair with only the dial indicator pin holding it in place. While the deburring tool stop is much closer to inside neck diameter than the universal pin of the case master, it seems there must still be enough slop there to allow some inconsistency due to technique or whatever. I could be wrong, though, and I'd love to hear that I am since the next choice costs over twice as much money.
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<br>Sinclair offers a case neck micrometer set on a stand which looks to be a mite more consistent in that you ratchet down the mic with a set force each time. Also the stand looks like it would be easier to use. It measures to .0001, not just .001, which is more than necessary as one only needs .001 accuracy, but the consistency and repeatability of measurements would seem to make it worthwhile. Kind of expensive, but the bottom line is that I'm after good results and what the heck, you can't take it with you.
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<br>How about a plain old ball micrometer? Would it be easy to use or a bit too clumsy?
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<br>SO - to repeat - what is the best tool out there for consistent and accurate results that is not so vulnerable to operator technique?

Jim,
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<br>Take a cleaning rod brush and cut off the brush. Screw the threaded end into the hole where the little pin goes on the Casemaster. Get an RCBS flashole deburring pilot of the appropriate size and put it on the piece of cleaning rod. Mark the area where the flash hole pilot covers the Casemaster neck measuring post. Remove the pilot and cleaning rod piece. Remove the Casemaster post and grind a flat in roughly 3/16" deep. You want enough room so tip of the dial indicator will clear the thick part of the flash hole pilot. Reinstall the Casemaster post, the cleaning rod piece, and the flash hole pilot. Set up your dial indicator as appropriate. Put a rubber band (mine is 1/4" wide) around the dial indicator so it increases the pressure on the tip.
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<br>If you do all this, you will have a quick and reasonably accurate way to measure neck thickness--much better than the Casenaster systen alone. You probably read my post where I did this, and subsequently shot four 3-shot groups with my 300 Win that averaged .364" at 100 yds.
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<br>Most importantly, call me before you do any of this. (210) 599-2092. It is much easier to describe with words than try to post without pictures.
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<br>Blaine

Jim,
<br> On the Sinclair Case Neck Thickness tool, the case is supported at two points while measuring neck thickness. The neck rides on the RCBS pilot stops, the rear of the case rides on the same rod the RCBS pilot stop is mounted on. The rod's end is small enough to fit inside the case's flashhole, it protrudes out 1/8". Believe me this tool is accurate and consistent. That rod is adjustable to the case's length so you can use it for just about any cartridge out there except a 50BMG. If your rifle's chambers have std neck dia. then this is the way to go, sorting by neck thickness.
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<br> By the way, I also have the Sinclair Cocentricity gauge. It is the Cocentricity Gauge to have IMHO. This tool is more suited to checking bullet runout, measuring die performance etc. I use it for troubleshooting if I suspect my handloads are the problem. Both tools are excellent quality, I feel my tight groups are partially owed to these tools and methods. E-mail me if you want, I can fax you the paperwork which came with my tools if you like. MtnHtr

AFP - Thanks - I followed your description okay, now that I know what an RCBS deburring tool pilot looks like I can see what you are doing. Then the rubber band around the dial indicator - you put it just around the exterior of the dial and over the top of the indicator probe to push it down, right? At first I was thinking that you wrapped it around the indicator probe and the cartridge neck or something to squeeze the two together.
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<br>Anywho - MtnHunter - I called Sinclair and that's how they described their tool. The fact that the cartridge is supported at both ends is a big selling factor to me. Then, they use a "pretty close" mandrel as it were, the same RCBS deburring tool pilot that Blaine found so useful.
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<br>I ordered one second day air and UPS should be delivering a Sinclair Neck Thickness Gauge in about 2-3 hours!
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<br>The same "man in brown" delivered a Redding Competition Neck Die set in .30-06 yesterday. Expensive dang bugger, but is has the competition neck bushing die - this has the sliding inner sleeve to support the whole cartridge case during sizing as opposed to the simple S die, and also has the Competition seater.
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<br>My only available cases had already been neck sized with a standard Redding neck die so I loaded up about 25 rounds using the competition seater die. Bullet runout according to the RCBS case master was about .002" to .003".
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<br>That's probably telling me that the standard Redding sizing dies are plenty good enough and that I'm spending well over $100 to gain a one thousandth inch runout advantage, but reloading is my main hobby and this added precision just adds to the enjoyment. And what the heck, it's only money, right?

Jim,
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<br>You are correct. The purpose of the rubberband is to increase the pressure the dialindicator applies to the case neck--it makes for smoother readings that way. I didn't know the Sinclair tool supported the case at the rear. I'll bet I can rig that up as well..........
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<br>Blaine

I'm new to this board and have been reading a lot of posts. I use a Cabinetree combo tester and it does support the case in two points. It checks most everything the RCBS does except case separation and also checks lead hardness. Costs about $85.00. It's on castingstuff.com web site.
<br>Dozer