I am about to load my first 5.56 rounds and have a case headspacing question.
The cases are from LC M885 fired once in my SIG556. The equipment includes a Lee Turret (Hornady LNL AP and Lee Classic SS available but not being used), Redding National Match Die Set, Hornady Comparator, Giraud Trimmer, and L. E. Wilson case gauge.
I deprimed and tumbled the brass, swaged it in a Dillon D-600 SuperSwage, debarred and uniformed the flash holes and primer pockets, lubed with Imperial Sixing Wax, and sized in the Redding die, measuring the before and after comparator lengths of each case. I then trimmed each case to 1.7523" in the Giraud.
I had previously set up the die to touch the shell plate, then about 1/8th further turn down. The press deflects slightly when I pull the lever, so I have some cam over.
I measured each of 107 cases with the Hornady Comparator, and got an average of 0.0029" shoulder pushback using the Redding Competition Shell Holder (0.006""). Thought I was GTG. Then I got an L. E. Wilson Gauge and all of the case bases I checked protrude slightly (about a rim's width) above the high step of the gauge.
At this point I figure the SIG556 must have larger than usual chamber headspace, and that I need more than .003" shoulder pushback to be within SAAMI spec, so I take some previously sized brass, put in the Redding Shell Holders 0.004", 0.002" and the standard Lee shell holder, increasing the shoulder pushback with each one. None of these resizings caused the case to properly fit the Wilson gauge: it seems I still did not push the shoulders back enough to be within SAAMI standards.
Not sure where to go from here. Options that come to mind include:
1) Lower the Redding sizing die, then see if case sized it it will clear the case gauge,
2) Try the Lee Dies until I can figure out how to set the Reddings,
3) Ignore the case gauge, load and fire these rounds and see what happens,
4) Ignore the SAAMI spec and assume the SIG556 has a very long headspace (same as 3),
5) Something else.
Thanks in advance.
The cases are from LC M885 fired once in my SIG556. The equipment includes a Lee Turret (Hornady LNL AP and Lee Classic SS available but not being used), Redding National Match Die Set, Hornady Comparator, Giraud Trimmer, and L. E. Wilson case gauge.
I deprimed and tumbled the brass, swaged it in a Dillon D-600 SuperSwage, debarred and uniformed the flash holes and primer pockets, lubed with Imperial Sixing Wax, and sized in the Redding die, measuring the before and after comparator lengths of each case. I then trimmed each case to 1.7523" in the Giraud.
I had previously set up the die to touch the shell plate, then about 1/8th further turn down. The press deflects slightly when I pull the lever, so I have some cam over.
I measured each of 107 cases with the Hornady Comparator, and got an average of 0.0029" shoulder pushback using the Redding Competition Shell Holder (0.006""). Thought I was GTG. Then I got an L. E. Wilson Gauge and all of the case bases I checked protrude slightly (about a rim's width) above the high step of the gauge.
At this point I figure the SIG556 must have larger than usual chamber headspace, and that I need more than .003" shoulder pushback to be within SAAMI spec, so I take some previously sized brass, put in the Redding Shell Holders 0.004", 0.002" and the standard Lee shell holder, increasing the shoulder pushback with each one. None of these resizings caused the case to properly fit the Wilson gauge: it seems I still did not push the shoulders back enough to be within SAAMI standards.
Not sure where to go from here. Options that come to mind include:
1) Lower the Redding sizing die, then see if case sized it it will clear the case gauge,
2) Try the Lee Dies until I can figure out how to set the Reddings,
3) Ignore the case gauge, load and fire these rounds and see what happens,
4) Ignore the SAAMI spec and assume the SIG556 has a very long headspace (same as 3),
5) Something else.
Thanks in advance.
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