.308 resizing issue

dbn80 · June 8, 2014, 04:04 PM

I am using RCBS Small base dies and a EGW chamber checker. About every 10 to 15 cases I get one that is not passing the chamber check, the head is sitting slightly above the top of the chamber checker. All cases are trimmed to same length, if that's even relevant. I re-calibrated the resizing die according to the instructions, I just can't figure out why I'm getting the occasional case that wont fit in the chamber even after using small base dies?? Is this normal? Do I toss these cases out or is there anything I can tweak to fix this? Appreciate any input.

Bart B. · June 8, 2014, 04:44 PM

I think what's happening is your press has enough spring that the die doesn't go all the way down sizing all the cases the same amount. That's why your case heads stick out of the case gauge varying amounts.

When your case is all the way up into the sizing die, does the bottom of the die touch the shell holder?

Your die may need to be turned down into the press; just a tiny bit. And mount that moves the circumference around about 1/4 inch is probably enought.

You can put one of these labels on your die lock rings so how much its height changes in the press can easily be seen:

http://i860.photobucket.com/albums/a...justment-1.jpg

dbn80 · June 8, 2014, 07:27 PM

Thanks for the response Bart. The die is definitely making contact with the shell plate on each stroke. I went ahead and did the 1/4 inch turn as you recommended. So I re-sized about another 60 cases after this, and as I put them in my chamber checker, the ones that don't appear flush after dropping them in do pass the check IF i put some pressure on the case with my thumb. But it is a pretty tight fit obviously. My thoughts are that in an AR10 with the bolt slamming the round in the chamber it would be ok? What do you think? Thanks again for your input!!

jepp2 · June 8, 2014, 08:20 PM

Are you sure there aren't burrs on the rims that is causing the head to sit high? I know on 223/5.56 sizing I always put them in the gage head first to make sure there aren't any burrs that give a false reading.

If the cases aren't sized with enough shoulder setback, you aren't going to shove them home with your thumb.

dbn80 · June 9, 2014, 02:05 PM

I don't believe it was burrs on that kept them from sitting flush but I'll go back and look more closely. Great suggestion on putting them in head first, I'll do that also. Thank you for the tip

**Unclenick** · June 9, 2014, 02:53 PM

Sometimes a badly stretched case will resist normal sizing. Lube and run the miscreants back into the sizing die and hold them there for a count of five, lower, rotate 1/3 turn and repeat, then do that a third, final time. I can usually take a couple more thousandths off length and maybe a quarter to a half a thousandth off diameter.

Try it. If it makes no difference, feel around each one for a burr that needs to be filed off. If that doesn't help, then set the cases up in a straight line on your table, press against the line with a ruler to even all the heads up, then sight down the row to see if the case shoulders and mouths line up well. If not, you likely have a bent rims. They can be straightened by firing in a bolt gun, assuming it has good lug contact and a true bolt face.

zeke · June 10, 2014, 09:50 PM

Are the cases all the same make, fired with same load?

dbn80 · June 11, 2014, 06:28 PM

Unclenick- great info thank you. I tried the 1/3 turn and hold as suggested and it appears to have helped. I took several cases that failed chamber check and tried this, some of them don't sit flush still but do with a little push of the thumbthumb. Which I couldn't do prior. I can put them through my bolt gun and see if that does anything.

Zeke- most if not all is Lake city brass. Bought a bunch of once fired brass and all I know is it was military. Visually all the cases look great

June 8, 2014, 04:04 PM	#1
dbn80 Junior Member Join Date: June 8, 2014 Posts: 7	.308 resizing issue I am using RCBS Small base dies and a EGW chamber checker. About every 10 to 15 cases I get one that is not passing the chamber check, the head is sitting slightly above the top of the chamber checker. All cases are trimmed to same length, if that's even relevant. I re-calibrated the resizing die according to the instructions, I just can't figure out why I'm getting the occasional case that wont fit in the chamber even after using small base dies?? Is this normal? Do I toss these cases out or is there anything I can tweak to fix this? Appreciate any input.

June 8, 2014, 08:20 PM	#4
jepp2 Senior Member Join Date: December 24, 2008 Location: Loveland, CO Posts: 1,476	Are you sure there aren't burrs on the rims that is causing the head to sit high? I know on 223/5.56 sizing I always put them in the gage head first to make sure there aren't any burrs that give a false reading. If the cases aren't sized with enough shoulder setback, you aren't going to shove them home with your thumb. __________________ NRA Benefactor Life member

June 9, 2014, 02:53 PM	#6
Unclenick Staff Join Date: March 4, 2005 Location: Ohio Posts: 21,063	Sometimes a badly stretched case will resist normal sizing. Lube and run the miscreants back into the sizing die and hold them there for a count of five, lower, rotate 1/3 turn and repeat, then do that a third, final time. I can usually take a couple more thousandths off length and maybe a quarter to a half a thousandth off diameter. Try it. If it makes no difference, feel around each one for a burr that needs to be filed off. If that doesn't help, then set the cases up in a straight line on your table, press against the line with a ruler to even all the heads up, then sight down the row to see if the case shoulders and mouths line up well. If not, you likely have a bent rims. They can be straightened by firing in a bolt gun, assuming it has good lug contact and a true bolt face. __________________ Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle Last edited by Unclenick; June 13, 2014 at 02:47 PM. Reason: typo fix

June 8, 2014, 04:44 PM	#2
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	I think what's happening is your press has enough spring that the die doesn't go all the way down sizing all the cases the same amount. That's why your case heads stick out of the case gauge varying amounts. When your case is all the way up into the sizing die, does the bottom of the die touch the shell holder? Your die may need to be turned down into the press; just a tiny bit. And mount that moves the circumference around about 1/4 inch is probably enought. You can put one of these labels on your die lock rings so how much its height changes in the press can easily be seen: http://i860.photobucket.com/albums/a...justment-1.jpg

June 8, 2014, 07:27 PM	#3
dbn80 Junior Member Join Date: June 8, 2014 Posts: 7	Thanks for the response Bart. The die is definitely making contact with the shell plate on each stroke. I went ahead and did the 1/4 inch turn as you recommended. So I re-sized about another 60 cases after this, and as I put them in my chamber checker, the ones that don't appear flush after dropping them in do pass the check IF i put some pressure on the case with my thumb. But it is a pretty tight fit obviously. My thoughts are that in an AR10 with the bolt slamming the round in the chamber it would be ok? What do you think? Thanks again for your input!!

June 9, 2014, 02:05 PM	#5
dbn80 Junior Member Join Date: June 8, 2014 Posts: 7	I don't believe it was burrs on that kept them from sitting flush but I'll go back and look more closely. Great suggestion on putting them in head first, I'll do that also. Thank you for the tip

June 10, 2014, 09:50 PM	#7
zeke Senior Member Join Date: November 17, 1999 Location: NW Wi Posts: 1,671	Are the cases all the same make, fired with same load?

June 11, 2014, 06:28 PM	#8
dbn80 Junior Member Join Date: June 8, 2014 Posts: 7	Unclenick- great info thank you. I tried the 1/3 turn and hold as suggested and it appears to have helped. I took several cases that failed chamber check and tried this, some of them don't sit flush still but do with a little push of the thumbthumb. Which I couldn't do prior. I can put them through my bolt gun and see if that does anything. Zeke- most if not all is Lake city brass. Bought a bunch of once fired brass and all I know is it was military. Visually all the cases look great