Exactly how I do it for many rifles. I have never been able to bump the shoulder without what I would consider almost a full length sizing. I'm sure that there are variations across dies and chambers that would allow for that but I have not seen it in any of mine.
FL size or neck size?
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Exactly how I do it for many rifles. I have never been able to bump the shoulder without what I would consider almost a full length sizing. I'm sure that there are variations across dies and chambers that would allow for that but I have not seen it in any of mine.
NeuseRvrRat
Member
agreed
Funshooter45
Member
Well... yeah, backing it out "a couple turns" and seeing what you get is one way of doing it. And then adjusting from there until it feels about right. But think about a few numbers first.
Let's say you screw the FL sizer die down all the way until it touches the shell holder and sized a case. Presumably, that gets it all the way down to minimum SAAMI size. We realize that is more sizing than most real rifles need. So, if you back the die out by one full turn, how much is that exactly? It is 0.071" less sizing. That is a LOT. IF that was the "perfect amount" of sizing for your rifle, it means that when firing a factory round, you would have had 0.071" of headspace. Backing the FL die out by 2 full turns means that you are now reducing the amount of sizing by 0.142", so basically, you're not even touching the shoulder at all.
So, think about if you just backed the sizing die out by 1/2 turn. You are backing it out by 0.036". A 1/4 turn means an adjustment of 0.018". That is still a lot of change. Remember, the GOAL is to just bump that shoulder back by about 0.002" or so compared to the fired case out of your rifle. A 1/8 turn is 0.009". This implies that a turn of about 1/32 of a revolution on your die changes the sizing by 0.002" How many of us can accurately measure 1/32 of a turn? I know I can't.
The better way is to take a case that has been fired in your rifle and measure the length to a fixed point on the shoulder. They make devices that slip over your case and you use your calipers to take that consistent measurement. Hornady sells a set for about $40. Or you can use your own bushing. It doesn't matter what it is as long as it will give you a consistent measurement to a fixed point on the shoulder. So, anyway, take that measurement and write it down. Now screw your FL sizing die all the way down until it touches the shellholder. Size the same case you just measured. Now measure it again. The fully sized case will obviously be somewhat shorter than the unsized case. This might be anything from 0.003" to maybe 0.015", perhaps a bit more in some cases. But for example, let's say it turns out the full length sized case was 0.009" shorter than the unsized case. And you decide you would really like to just bump the shoulder back by 0.002", rather than 0.009". What you do is get your 0.007" feeler gauge out and put it between the top of the shellholder and bottom of the die when you screw the die down. Now lock the lock rings down on the die and you will get your shoulders bumped back by exactly 0.002" every time. It's more precise than turning your die a 1/2 turn or a 1/4 turn or something until it just feels about right. It only takes a minute or two to do it.
Let's say you screw the FL sizer die down all the way until it touches the shell holder and sized a case. Presumably, that gets it all the way down to minimum SAAMI size. We realize that is more sizing than most real rifles need. So, if you back the die out by one full turn, how much is that exactly? It is 0.071" less sizing. That is a LOT. IF that was the "perfect amount" of sizing for your rifle, it means that when firing a factory round, you would have had 0.071" of headspace. Backing the FL die out by 2 full turns means that you are now reducing the amount of sizing by 0.142", so basically, you're not even touching the shoulder at all.
So, think about if you just backed the sizing die out by 1/2 turn. You are backing it out by 0.036". A 1/4 turn means an adjustment of 0.018". That is still a lot of change. Remember, the GOAL is to just bump that shoulder back by about 0.002" or so compared to the fired case out of your rifle. A 1/8 turn is 0.009". This implies that a turn of about 1/32 of a revolution on your die changes the sizing by 0.002" How many of us can accurately measure 1/32 of a turn? I know I can't.
The better way is to take a case that has been fired in your rifle and measure the length to a fixed point on the shoulder. They make devices that slip over your case and you use your calipers to take that consistent measurement. Hornady sells a set for about $40. Or you can use your own bushing. It doesn't matter what it is as long as it will give you a consistent measurement to a fixed point on the shoulder. So, anyway, take that measurement and write it down. Now screw your FL sizing die all the way down until it touches the shellholder. Size the same case you just measured. Now measure it again. The fully sized case will obviously be somewhat shorter than the unsized case. This might be anything from 0.003" to maybe 0.015", perhaps a bit more in some cases. But for example, let's say it turns out the full length sized case was 0.009" shorter than the unsized case. And you decide you would really like to just bump the shoulder back by 0.002", rather than 0.009". What you do is get your 0.007" feeler gauge out and put it between the top of the shellholder and bottom of the die when you screw the die down. Now lock the lock rings down on the die and you will get your shoulders bumped back by exactly 0.002" every time. It's more precise than turning your die a 1/2 turn or a 1/4 turn or something until it just feels about right. It only takes a minute or two to do it.
The guys who are adjusting the sizer until the bolt just does close with a hair of resistance don't make that big an adjustment if they are doing it right.
Which is how I do it.
http://www.thehighroad.org/showthread.php?t=504759
Funshooter45
Member
Yeah I knew you were doing it that way. My post wasn't directed specifically at anyone, I was just chiming in my thoughts on the general topic of partial length sizing and shoulder bumping. It's old hat to most folks here, but I had to have it explained in detail to me before I really understood it.
Funshooter wrote "They make devices that slip over your case and you use your calipers to take that consistent measurement. Hornady sells a set for about $40. Or you can use your own bushing."
I use a hex nut that I dressed two opposing sides with fine emery paper and drilled a hole large enough to clear the neck to rest on the shoulder. Works great. I do the same thing on another flat only a smaller hole that works when measuring the seating depth from a point on the ogive of the bullet. Also works great ... and it's a lot cheaper than $40.
I use a hex nut that I dressed two opposing sides with fine emery paper and drilled a hole large enough to clear the neck to rest on the shoulder. Works great. I do the same thing on another flat only a smaller hole that works when measuring the seating depth from a point on the ogive of the bullet. Also works great ... and it's a lot cheaper than $40.
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