Dultimatpredator
Well-known member
I don’t own a headspace gauge so I grabbed a spent 45 ACP cartridge and slipped it over a few of my fired 243 casings. The AOL’s were 2.461”,2.462” and 2.461”.
Then I measured some casings I ran through my small base die. I followed RCBS’s instructions and lowered the die down till it touched the shell holder, raise the handle, and then turned the die down one quarter turn. The measurements were 2.452”, 2.450”, and 2.453”.
I realize this I sent the most accurate way of measuring headspace but I’m sure it probably got me pretty close.
So if I add and divide by three I’m approx .009” less. How far do you shooters Bumb your headspace back off your AR’s? I read on a couple of forums some recommend .004? I would think there’s not a lot a room for error with .004” in an auto or AR style rifle eventually causing chambering issues?
To be honest this is the first time I’ve ever checked for head spacing...and I’ve been reloading for 20 years. In the past I’ve just always turned my dies down a quarter turn after it touches the shell holder as in the RCBS’s directions and never had issues with this practice along with making sure I loaded under the chambers max AOL. I just wanted to check my 243 AR since I knew it had a tight chamber. So if I didn’t check it I’d be loading with a quarter turn down as usual. So if .004” is correct and I’m too short by .005” I would assume I’m just shortening my brass life?
I have done the 1/4 turn die set on my other bolt guns and POF P415 and can shoot .3” groups with my loads at 200 yards when I do my part so I’m sure accuracy is not as much or even an issue...it’s just the brass life, and stretching issues I would assume?
Update,
I just got off the phone with RCBS customer service and was told .009” was where I wanted to be at ...or close to that measurement range” is where I wanted to be away from the chambers shoulder, give or take, was the quote. I asked what was the acceptable measurement range variance for AR’s but he wouldn’t give me an exact range measurement for some reason.
Then I measured some casings I ran through my small base die. I followed RCBS’s instructions and lowered the die down till it touched the shell holder, raise the handle, and then turned the die down one quarter turn. The measurements were 2.452”, 2.450”, and 2.453”.
I realize this I sent the most accurate way of measuring headspace but I’m sure it probably got me pretty close.
So if I add and divide by three I’m approx .009” less. How far do you shooters Bumb your headspace back off your AR’s? I read on a couple of forums some recommend .004? I would think there’s not a lot a room for error with .004” in an auto or AR style rifle eventually causing chambering issues?
To be honest this is the first time I’ve ever checked for head spacing...and I’ve been reloading for 20 years. In the past I’ve just always turned my dies down a quarter turn after it touches the shell holder as in the RCBS’s directions and never had issues with this practice along with making sure I loaded under the chambers max AOL. I just wanted to check my 243 AR since I knew it had a tight chamber. So if I didn’t check it I’d be loading with a quarter turn down as usual. So if .004” is correct and I’m too short by .005” I would assume I’m just shortening my brass life?
I have done the 1/4 turn die set on my other bolt guns and POF P415 and can shoot .3” groups with my loads at 200 yards when I do my part so I’m sure accuracy is not as much or even an issue...it’s just the brass life, and stretching issues I would assume?
Update,
I just got off the phone with RCBS customer service and was told .009” was where I wanted to be at ...or close to that measurement range” is where I wanted to be away from the chambers shoulder, give or take, was the quote. I asked what was the acceptable measurement range variance for AR’s but he wouldn’t give me an exact range measurement for some reason.
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