getting perfect neck tension

[foreign]

i had an epiphany the other day and am sure that im not the first to have it. wanting to know if anyone has dont this yet and thoughts and results.
so my epiphany was to take brass that was for a caliber bigger that mine. eg .243 or my .308 and size it in the die for the caliber i want. this should make the thickness of the neck more than it would normally be. should also make them longer. then i can neck trim to get the necks down to a thickness i want, which will give me the tension i want and the tension should be completly even since the whole neck will be even. i can also then trim the cases to a length of .010 shorter than my chamber.
i guess i could use .308 brass for the .243 and something like.270 for the .308.
not to sure if that thought process of mine will make sence how ive writen it.
but any thought?lightbulb

 

[Michael Eichele]

I think you are trying to just get the same wall thickness all the way around the necks as well as make them the same from case to case??????

A very simple way is to "turn" your necks. This makes them "even" or concentric is a better term. There are a whole bunch of tools available to do this. You only need to take .001-.003" to do this. I dont think necking down affects the wall thickness to any measurable degree. I could be wrong though.

Once your necks are turned to the same wall thickness all the way around, you can use just about any style of neck sizing die to get consistent neck tesnion.

Hope that makes sense.

 

[Pdvdh]

I use 338 Win Mag brass to form 7mm Rem Mag brass. The necks do thicken up some, and this reduces some of the slop between the case neck OD and the chamber throat ID on my two factory rifles. I outside neck turn with a K&M tool. I do basically exactly what I understand you're thinking about doing. Don't ask me to prove that it improves accuracy and if it's worth the time and effort. I don't shoot enough to prove it to myself, let along others, and I'm not interested in wasting barrel life trying to prove that point. Competition shooters like tight-necked chambers, so what could it hurt to move in that direction with my factory chambers. There's still plenty of case neck to throat separation with factory chambers even with necked down & thicker case necks. Just less than if I was running 7mm RM brass. I also anneal the case necks after sizing down. Do these 338 WM cased reloads shoot well out of my two Tikka T3 factory rifles/barrels? And do I have low case neck runout? Yes & yes. I do have to use larger ID Redding neck bushings with the parent 338 > 7mm cases than was required with 7mm Rem Mag brass. I've done this with both Federal 338 WM and Winchester 338 WM brands of brass. Before selecting the brass to use, I measured the outer diameter of loaded factory rounds to figure out which brand of brass typically had thicker case necks. Federal was thicker. I use Federal brass in one of my rifles, and the WW brass in the other so I know which shells go with which rifle.

Oh yeah, I periodically get some weird looks when I tell people I'm shooting 7mm RMs should they happen to look at my case heads and see them stamped 338 Win Mag.

 

[BountyHunter]

Your problem will not be getting the neck tension the same initially, it will be keeping it the same after firing! They work harden every time you fire them and not always to the same degree. You will find cases that are inherently tighter than others and that is on turned cases too.

In the 1k BR game we have gone thru every evolution trying to do that. Some guys sort their cases with pin gauges after sizing to the .0005 and do it that way. Lot of work, but seems to work for them.

Others use the KM arbor press with dial indicator on top and use arbor seating dies and only use rounds that seat measuring the same force. All others are sighters.

Others buy cases by the 1000 or more, weigh and sort, fire them 3-4 times and throw away and start all over.

I have done both and at the end of the day, I bought an annealing machine and anneal every time. I use an KM press and if one case seats harder than the others it goes into the sighter row. That seems to be the easiest and fastest.

BH

 

[Pdvdh]

BH,

Glad you posted. I was hoping someone from the competition curcuit would sound in.

 

[foreign]

cheers for the replies. what im hoping on doing is what ur doing phorwath but with a different caliber. i think i might annel first so i hope the necks will "grow" more and get thicker.(easier flow of brass when soft is my reasoning).
bhunter. i hear what ur saying but i want to try to decrease the difference in the od of my brass necks and the Id of my chamber. read somewhere that its better..
then i can neck turn and once i have taken of some material should still have more thickness and greater or the same od of brass for that caliber before its been neck turned.

 

[Digger49er]

I have a 338 Tomahawk which is based on the Remington Ultra Mag case. I prefer to neck the 375 cases down before fireforming them. My reasoning for this is to give the case a little more meat before I turn them down, which in turn should give me a more concentric neck and even neck tension by my way of thinking. It seems to work for me and case life isn't all that bad.

I have to admit I'm a bit anal when it comes to brass. I turn necks, uniform primer pockets, weigh brass etc for all my reloads. I don't know if it's really worth the time for an average hunting rifle but what the hell ............it doesn't hurt either. The way I see it every little bit helps when your talking accurate reloads.

gun)