neck turning tolerence

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mitchellchandler_au
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neck turning tolerence

#1 Postby mitchellchandler_au » Thu Apr 06, 2006 9:44 pm

Hi all,
Being new to fclass iam having a 6mmbr made. I just started turning my necks on a K&M neck turner, my necks have about a quarter thou variation. Is this too much? can any one give me some tips on neck turning in general?

Thanks,
Firepower usally means an increased number of misses per minute. 50 misses are not firepower. One hit is firepower

AlanF
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#2 Postby AlanF » Fri Apr 07, 2006 8:08 am

Mitchell,

If you are getting a quarter thou then that is a huge improvement on some of the variations in neck wall thickness of new brass (I've seen up to 3 thou).

With the K & M I'd recommend a couple of things - only use it by hand - don't use it with a drill or you'll get overheating. Also, to avoid the setting from "drifting", I set the adjustment screw in a clockwise direction, then tighten the locking screw, then go back to the adjustment screw and tighten it clockwise.

Alan

Cameron Mc
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#3 Postby Cameron Mc » Fri Apr 07, 2006 8:43 am

Hello, just wondering if you need to neck turn, ie, tight neck chamber. If not and still wish to to neck turn, just remove minimum amout of brass. I have found Lapua BR brass is best left as is if using standard chamber. A quarter thou should not cause problems.
I spin my neck cutter in a lathe chuck and feed the cases by hand. You could use the turner in a drill chuck. It is important to use lube.

Cameron

mitchellchandler_au
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Location: MIA

#4 Postby mitchellchandler_au » Fri Apr 07, 2006 1:35 pm

Cameron,

I have no choice but to turn as the chamber is cut to .269 not the standard .271-272 neck.

Thanks for your tips.
Firepower usally means an increased number of misses per minute. 50 misses are not firepower. One hit is firepower

Cameron Mc
Posts: 1089
Joined: Tue Jun 28, 2005 10:55 am
Location: Darling Downs SE Qld

#5 Postby Cameron Mc » Fri Apr 07, 2006 5:52 pm

Mitchell, I too have a 6br set up with a .269 neck. I turn mine to measure .268 when loaded.
I am not familiar with the K & M turner, I use one I have made myself. If the K & M has a full cylinder mandrel/pilot make sure you use lube and probably turn by hand, as Alan suggested, as there can be alot of friction.
I machine flats on my mandrels/pilots to greatly reduce friction and hence speed up the process.

Hope this helps, Cameron

hypoxia88
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Joined: Mon Apr 03, 2006 5:13 am
Location: WA

K&M neck turning tool

#6 Postby hypoxia88 » Sun May 28, 2006 9:10 pm

Recently I neck turned 400 Lapua 0.30cal cases. Cases turned at approx 60 rpm by a variable speed drill fixed in a vise. Imperial lube on the mandrel before every case, and most importantly, K&M tool kept in cold water between cuts. Unless the tool is presented to every case at the same temperature there is variation in the cut depth, and the mandrel heats quickly when in use. Spray the tool with a good waterproof/lube (lanolin products are good) before putting in water, then dry with compressed air/slow heat after use. Imperial wax prevents brass build up on mandrel and the 'cool' tool cuts every case to the same dimension. Do a rough cut first then adjust tool and do the finishing cut.
It's a pity my carefully crafted ammunition does not help me pull a good shot! Once again its the nut behind the butt that sends them astray. Good ammo certainly does help the good shots score higher though.
Fly high, shoot straight.

ned kelly
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Location: Woodend, Victoria

#7 Postby ned kelly » Tue May 30, 2006 8:39 pm

G'Day Mitchell
I use a K&M and to give you an idea of the relative wall thicknesses I miked 50 .223 lapua cases with a Mitutoyu 1/10,000 thou tubing mike (that right 1/10 of a thou) The variation was approx. from 11.2thou to 11.7thou variation measured in 4 places around the neck.

I still turned them all to measure wthin 2/10 thou or better (I'm a BR shooter and cant help myself) I want/need to guarantee those VLD's are perrfectly aligned with the centre of the chamber and bore so they fly straight. Any misalignment will cause the bullet as it leaves the barrel to be spinning with wobble caused by the misalignment. This ensures that long bullet settles down to stable flight quickly as possible.

As for turning I use a cordless drill to make 2 cuts that approach the final size and cut the last cut by hand to ensure even temperature of the cutter and the mandrel. Any change in temperature of the neck turners mandrel will cause variations in wall thickness. I use imperial sizing die wax as a lube and use plenty of it you cannot afford to have brass build up on the mandrel due to insufficent lube or you will end up cutting more off the case neck than you intended. Precision Shooting Mag has an excellent book on reloading techniques including a great chapter on neck turning.

Hope this is some help
Cheerio Ned Kelly


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