Necking down a case

[Neo]

OK I'm not new to reloading but I have never had a gun chambered in a wildcat. A friend of mine has a 7mm that is necked down to 6mm. He has the dies for it and I'm wondering what is involved in necking down the brass. Is it done in stages or all @ once any help would be great
Thanks

 

[Victor N TN]

Re: Necking down a case

Lube one case really well and try it. I used to step down LC Match 30-06 brass to 25-06. I made a die close to what a .270 die is and ran them through that one step.

WARNING...!!! When you neck down brass the necks get THICKER. Depending on the chamber that was cut, he may need to turn the case necks. A sloppy factory chamber can sometimes get by. But a custom chamber probably won't. I would use one case without powder and seat a bullet. Then see if it feeds OK.

Personally I would cast the chamber and measure everything to be safe. I like a minimum of .0015" PER side. That's .003" difference in the ID of the chamber neck versus the measured case neck with a seated bullet.

Better safe than sorry.

 

[81Z4ME]

Re: Necking down a case

Mostly I neck "up". I have (very seldom) necked down.

I turn all .243 Win., and even 6mm Rem. I find into .308 brass. Every now and then I've run a piece or two of .358 Win. through the dies but seems I hardly ever find any of that stuff.

I turn all 25-06, .270 Win., .280/7MM Express Rem. into 30.06 brass.

I use standard dies. I put extra lube on the brass and make sure the inside of the neck is lubed and I trim the brass afterwards to make sure its the right length.

The point made above about neck wall thickness should be listened to. The only place that brass can "go" is into the neck wall thickness when reducing neck OD. One quick check might be to measure the OD of some factory rounds necks and compare to your necked down brass reloads (bullets seated in the reloads to make sure you're measuring/comparing the same thing.) There are a couple way to reduce neck wall thickness. Cheapest way may be reaming out the neck (some case trimmers, maybe all, can be used to trim and reduce neck wall thickness)but that is supposed to produce a less uniform wall thickness vs. neck turning.

 

[Neo]

Re: Necking down a case

Thanks for the info. Next ? I'm thinking about starting out with 105gr. A-maxes with H4831 powder any idea what a starting load would be I'm thinking around 38 gr. and working my way up that's the starting load for a 243 win the rem 6mm is 43 grs. I do know what to look for in the way of pressure signs.
Thanks again guys.

 

[81Z4ME]

Re: Necking down a case

When I'm loading I look at my paper manuals and logbook. Here at the house I look at these as a reference.

http://data.hodgdon.com/cartridge_load.asp

 

[yotefever]

Re: Necking down a case

As long as I use enough Imperial Sizing Wax but not too much I never have a problem necking up or down.

 

[rksimple]

Re: Necking down a case

I neck down 7-08 brass to 260. Its as difficult as running the case through my 260 die once and firing.

 

[6mmFan]

Re: Necking down a case

.284 to .264 is not too much. .284 to .243 is quite a bit. Might take 2 steps. +1 on the imperial wax. I missed what caliber you were necking down to- so hard to say what powder charge.