Savage 10 headspacing a 308 barrel

[joeb33050]

I fl size brass and use that brass to set headspace when changing barrels. In 223, 22-250 and 308 the fl dies size the case to ~ .002 under the RCBS Precision Mic zero.
On occasion I find a case that has correct headspace per Precision Mic, but when fl sized, still won't go in the gun.
I take a spare barrel, put the case in the chamber, and tap the head with a plastic mallet. Tap, slightly!
Each tap, try the case in the gun.
All cases eventually go in all guns.
I don't know WHY cases that measure for headspace correctly don't go in some guns, but it happens to me occasionally.

I received a Shilen 22-250 barrel, put it on a M10 action and shot it. Some cases refused to chamber. I went through the lot of 89 cases, and found that 5 of the 89 had headspace ~-.002" on the RCBS Precision Mic, and would not chamber in the shilen barrel. Using a M110 spare barrel, a few light taps got each of the cases in the 110 chamber and cases chamber easily in the shilen barrel..
Cartridge headspace can be correct and some/few cases will not chamber.

[yew plucker]

I have a savage 10 in .204
bought a used .308 barrel (app 200-300 rounds on it)
changed the bolthead to .308 ( the one that was in my 7mm08, bought PTG for it)
using forester guages to check headspace, all is good, I know my problem is in my ammo. My hand loads. Just not sure where.

go gauge = bolt close
nogo =no bolt close
sammi factory round = bolt close
my handloads = no bolt close
handloads are seated at 2.800

LC brass FL sized
trimmed to 2.005
No crimp
lee dies

i know I'm missing something just can't think of why it is, built a 7mm08 with no issues.

After I did my first barrel change, NONE of my resized brass would fit either. I had to reset me sizing die down to its lowest point, to where the ram cams over a bit. You must be able to feel this happening. Then the brass would fit but it was tight. I have a friend with a lathe and we turned 15 thou off the bottom of the die and all works well now.

Remember, virgin brass is slightly undersized. Once fired brass has lost a small amount of its elasticity and has stretched as far as it possibly can under firing pressure. With a tight chamber it means a VERY tight bolt closing just on your "go" headspace. It will need to be resized slightly below the spec were you want it because it will spring back a bit. I use a Dillon cartridge gauge to tell me if the brass has been sized enough. These Dillon gauges are wonderful tools for the money.

[yew plucker]

On a related note, I resized a bunch of LC brass. Some of them simply would NOT size down to where they needed to be. Probably one out of twenty was like this. I just chunked them and called it the cost of doing business.