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F. Guffey · February 6, 2013, 09:36 AM

Question on Neck Sizing .308 for M1A

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I recently purchased an RCBS neck sizing die for .308 I shoot from my Springfield M1A (Loaded version). Neck sized some recently fired brass this evening and then dropped it into an L.E. Wilson headspace gauge. Noticed it sat a bit high in the gauge and checked closer with my micrometer and found that the neck sized brass was on average .004 high (from top of where it's measured from the guage). Is that a problem? Does it mean that headspace in my chamber is a bit over spec? I assume that the L.E. Wilson gauge is at industry spec. I'm loading 168gr Sierra HPBTs over about a 90 percent of max charge in Winchester brass. Does something I'm doing, or what I'm shooting, rule out neck sizing? For this particular rifle, I've always FL sized in the past. No issues. Fairly good accuracy. Thought neck sizing would allow me to tighten up my groups a bit.

Thanks...

.004” above the gage, later the question is “Is that a problem?” Next time measure the length of the case from the datum/shoulder of the case ‘to above the gage’ before firing, measure the length of the case from the datum/shoulder to the head of the case (above the gage) before neck sizing. The Wilson case gage allows for measuring the length of the case from the datum/shoulder to the head of the case on new minimum length/full length sized cases and fired cases, and as always the Wilson case gage will allow for measuring the length of the case from the shoulder of the case back to the head of the case and from the shoulder forward to the end of the neck.

Fat cases are fired cases, fat fired cases can be dropped into a Wilson case gage. The other gage is similar to a chamber gage, fat cases can not be dropped into a chamber gage.

Chamber gage, case head protrusion and the smith made me a case gage for my new rifle he built, if the smith made a chamber gage for a rifle he built he would have matched ‘case head protrusion’, instead he made a case gage for full length sized/minimum length cases. Then there is the ‘tomato stake barrel’, material? Most barrels have enough metal in them to make 3 chamber gages.

F. Guffey

February 6, 2013, 09:36 AM	#16
F. Guffey Senior Member Join Date: July 18, 2008 Posts: 7,249	Question on Neck Sizing .308 for M1A -------------------------------------------------------------------------------- I recently purchased an RCBS neck sizing die for .308 I shoot from my Springfield M1A (Loaded version). Neck sized some recently fired brass this evening and then dropped it into an L.E. Wilson headspace gauge. Noticed it sat a bit high in the gauge and checked closer with my micrometer and found that the neck sized brass was on average .004 high (from top of where it's measured from the guage). Is that a problem? Does it mean that headspace in my chamber is a bit over spec? I assume that the L.E. Wilson gauge is at industry spec. I'm loading 168gr Sierra HPBTs over about a 90 percent of max charge in Winchester brass. Does something I'm doing, or what I'm shooting, rule out neck sizing? For this particular rifle, I've always FL sized in the past. No issues. Fairly good accuracy. Thought neck sizing would allow me to tighten up my groups a bit. Thanks... .004” above the gage, later the question is “Is that a problem?” Next time measure the length of the case from the datum/shoulder of the case ‘to above the gage’ before firing, measure the length of the case from the datum/shoulder to the head of the case (above the gage) before neck sizing. The Wilson case gage allows for measuring the length of the case from the datum/shoulder to the head of the case on new minimum length/full length sized cases and fired cases, and as always the Wilson case gage will allow for measuring the length of the case from the shoulder of the case back to the head of the case and from the shoulder forward to the end of the neck. Fat cases are fired cases, fat fired cases can be dropped into a Wilson case gage. The other gage is similar to a chamber gage, fat cases can not be dropped into a chamber gage. Chamber gage, case head protrusion and the smith made me a case gage for my new rifle he built, if the smith made a chamber gage for a rifle he built he would have matched ‘case head protrusion’, instead he made a case gage for full length sized/minimum length cases. Then there is the ‘tomato stake barrel’, material? Most barrels have enough metal in them to make 3 chamber gages. F. Guffey