I know I'll catch hell for not checking from the get go and loading 100 rounds and then realizing my mistake, but admittedly I made an error when full length resizing my brass and set the shoulder back too far and now there is between 0.009 and 0.010" of difference in the shoulder of a fired case and the brass I reformed. This is for an
M1 Garand using mil-surplus Greek HXP brass (30-06 obviously). I know that the standard most use for bolt guns is either to fire form or leave 0.001"-0.002" but autoloaders should be closer to 0.004" to ensure proper chambering.
*My main question is: Is it safe to shoot this brass this one time to get it back to fire formed size and set my dies properly for the next round of resizing or if I have an unsafe headspace situation that's either dangerous to me or the rifle? Basically will I just be unnecessarily working the brass too much this one time but will be fine or it's not safe and I should just discard the brass?
Also, I've been using a Hornady headspace gauge using a comparator to see how far the shoulder is set back compared to a fired case. The measurements I get (even on other rounds like a non-fired factory case, fire formed, etc) pretty much all come up below SAAMI spec minimum. From what I've learned, this gauge is meant for comparison purposes only and something like the RCBS precision mic is needed to accurately gauge the distance from the case head to proper datum line on the shoulder (and that the measurements tend to read short for everyone due to the design w/ the beveled soft aluminum edge). The SAAMI min-max difference is 0.007" if I'm reading the SAAMI schematic correctly, but again, the comparator style gauge I'm using makes it seem like I'm well below SAAMI and I'm well below the min (could be in....not sure).
*Do I even need to worry about SAAMI spec or is measuring relative to a fire formed case all I should worry about? I assume that if I'm using that brass only in the one rifle then it doesn't matter, but if I wanted to make a round that would fit in virtually any chamber that I should then ensure it's inside of the SAAMI min-max, no?
Sorry for such a long set of questions. I've been hand loading for about two years now and am beyond novice status, but don't want to get careless and do something stupid. I know that excessive an headspace situation (or brass that's out of spec at the shoulder...similar effect) isn't something to be taken lightly. I'd hate to jeopardize my rifle or myself over $50 worth of brass that I should maybe just discarded.