False Shoulders

[panhandle]

When your fireforming brass and going to use a false shoulder as your positive headspace stop, how much must you expand the neck? Is one cal. enough to do the job or is more needed?
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Dick Coss

[Lone Star]

I believe you need at least a 0.5mm difference in bullet diameter.  The difference between a .270 and 7mm shoulder is only 0.0035" per side.  Between a 6.5mm and a 7mm it is 0.10".


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[panhandle]

On the 2 rifles that I'm building, one would be a 243 Win necked to 224 and the other would be 284 necked to 264.  It appears that they would then have enough resistance for a false shoulder.

[Reed1911]

You should be fine on both,

[Catfish]

Pandhandlepr,
   Are you building a .243 Middlestead?
   As long as you have enough back pressure to hold the hold the primer where the firing pin can set it off your good to go. Stay with faster burning powders when fire forming and near full loads at least. Using liter loads of slower powder I have had trouble completely forming the shoulders in my .411 Hawk.

[k3yston3]

I've only played around with false shoulders on one cartridge and I was given some advice from my gunsmith at the time to neck up at least 2 calibers in order to create enough of a false shoulder, so I stuck by that recommendation and had plenty of success with minimal case losses