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Thread: Headspace Measuring Questions

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    Member kodiakrain's Avatar
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    Default Headspace Measuring Questions

    So I go out to the range to fire some Federal and Remington Factory Loaded cartridges today, comparing them to some handloads (using Fed brass) that have been fired only twice so far and FL sized.
    they are all "measured out" prefiring, hoping to find my headspace numbers and trying to "understand the instructions" on my RCBS Precision Mic - for .270WSM

    Can you guys check this out and tell me if this looks right?
    Factory Remington 130gr Core-lokt FSP (average thru 5 rounds)
    Prefired -.003 Post Fired -.001, then Resized -.004

    Factory Federal 130gr Power shok SP
    Prefired -.0035 Post Fired -.0005, then Resized -.003

    Handloads after one time FL sizing and Firing then FL sized a second time
    Prefired -.0035 Post Fired -.002, then Resized -.004

    The FL Sizing die was not changed or adjusted thru all these sizings.

    My main question, before I continue to FL size these on this Die Adjustment, is it ok for these to be all in the (-) as in all below the ANSI minimum? Does this make sense or do you guys see something wrong in what I am doing? Or in the headspace dimensions of this rifle, a Sako 85. New with less than 500 rounds thru the barrel. Also why is there any variation in the Headspace of a fired round? Different brass, or what?

    Thanks for the advice
    Ten Hours in that little raft off the AK peninsula, blowin' NW 60, in November.... "the Power of Life and Death is in the Tongue," and Yes, God is Good !

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    Moderator stid2677's Avatar
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    Default

    Can you guys check this out and tell me if this looks right?
    Factory Remington 130gr Core-lokt FSP (average thru 5 rounds)
    Prefired -.003 Post Fired -.001, then Resized -.004

    Using the example above I would resize to -.002, That would be -.001 shorter than your post fired measurement.

    The idea is to work your brass as little as possible. If your headspace is -.001 and you resize to -.004 that is about .002 more than required and the brass will expand to fill the chamber when fired.

    Good luck

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    Default

    Iím easily confused, but if youíre asking if brass might size differently depending on how, or how many times itís been sized, Iíd say that was a definite maybe. However, I have no instances of verification to site.

    Also, when you buy these tools to measure things, you are led to believe that the measurements are all gonna be easy and certain, just like clockwork, but IME, thatís not so. Instead there are variations, both in the measurements, and in the way they are measured, if that makes any sense.

    Measuring headspace???, the length from mid-shoulder to the case head, can help you determine if you are sizing your brass too much, overworking, it and shortening case life.

    As a rule, I donít do that. Iíve not had issues with short case life, and I believe that a .001 or two, wonít make much difference in case life, anyway. Some, may consider that to be rationalizing, or lack of experience, on my part, so I wonít contend with anyone on it.

    If there is a problem to be solved, or something to be learned, then taking those measurements are a good idea.

    Smitty of the North
    Walk Slow, and Drink a Lotta Water.
    Has it ever occurred to you, that Nothing ever occurs to God? Adrien Rodgers.
    You can't out-give God.

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    In a perfect world zero headspace would be perfect. But in a hunting rifle in the field where dirt and other fluff can get on ammo, a little room for fluff is a good idea. .002"/.003" is a good range for a margin for less than sterile ammo with out excessive stretching of the case. A little closer will probably help brass life but will also raise the risk of a dirt related malfunction. Shims from note book paper are about 2 1/2 to 3 thousands thick and work pretty good placed between the boltface and a round to test for head space with loaded rounds.

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    Member kodiakrain's Avatar
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    "If there is a problem to be solved, or something to be learned, then taking those measurements are a good idea."
    Smitty of the North[/QUOTE]

    This is my reason for buying the tool, to answer two questions, "how I should be using the Placement of the Sizing Die to Size Best." I was only using the RCBS Die Instructions when installing the dies and had no idea what was meant by terms like "bumping the shoulder back" heard from more experienced guys. So learned there is quite a bit of adjustment that can be made there and am now screwing down to contacting the Shellholder then a 1/4 turn further down (by instructions) then backed it off 1/8 at a time to see this adjustment. As it worked out 1/8 turn further back out is a better sizing for my brass.
    Then more importantly I am still a bit mystified by my "neck Sizing Issues" problem (from another batch I posted about) where only 3 of 20 rounds were apparently sized wrong. Why did the other 17 work fine when there was no change in the Die adjustment? Looking for problems with my rifle or technique.
    If anything is clear from this new tool it is the amount of variance I have found in brass, for some reason I was surprised by this but it explains a lot.

    "Instead there are variations, both in the measurements, and in the way they are measured, if that makes any sense." Smitty again

    This was my first discovery and took a bit to realize I was the problem until I steadied my measuring technique. Also throughout 40 cartridges there is a surprising amount of variance even after I got my measuring technique down.

    Thanks for the Input you guys, I'm learning a lot here.

    One other thing is having used 95% only Federal brass, then measuring before and after firing some Remington Brass I am finding the Rem stuff is way more uniform in every way. Especially noticeable was when uniforming the Primer Pockets afterwards, the Rem stuff is already very uniform and the Uniformer barely does anything to it but clean it out vs. the Federal brass that has a little bit of brass shavings come out the first time, on every casing.

    I figured Fed was top of the line stuff but it does not appear to be so from the Factory rounds I have used compared to Remington.

    Any comments on the Brass you guys are using, some brands much better than others? All I see in the stores is Rem or some that look like "high end brands" I haven't used anything that wasn't factory ammo first. What should I look for when it gets to the point of buying brass to reload with?
    Ten Hours in that little raft off the AK peninsula, blowin' NW 60, in November.... "the Power of Life and Death is in the Tongue," and Yes, God is Good !

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    Default Good info, there.

    Kodiakrain:
    Yeah, I've always believed there are variations in brass, and I've had trouble getting consistent measurements too.

    You hear a lot of stuff, depending on where you're listening, I guess.

    "Winchester brass is better than Remington brass".
    "Federal brass is no-good".
    "Lapua brass is the bestest there ever was".
    "Norma Brass is too SOFT".

    This stuff gets repeated over an over again, and is accepted as knowledge, especially by those who think it makes them, so.

    I gather that different batches of brass are better or worse than others because machines at the factories wear, and need to be repaired or replaced from time to time. ??? I believe you can encounter bad, or badder brass with any brand, because that just makes sense, IMO.

    FL sizing a case is more than just "bumping the shoulder back", so the term might mean sizing enough that the shoulder IS set back. ???

    Smitty of the North
    Walk Slow, and Drink a Lotta Water.
    Has it ever occurred to you, that Nothing ever occurs to God? Adrien Rodgers.
    You can't out-give God.

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    I think Smitty covered it pretty well. I will say that I like to use only one brand of brass per a given load and try to keep the number of times it has been fired the same in a given batch. As for a specific brand, I'm not real picky. But I'm not a bench rest shooter and only load for hunting rifles so 1 moa or under suits me just fine. If you are trying for 1/2 moa or better you are going to have to get more anal. While you are first starting to reload, I would be less concerned about ded nutz accurate until I figured out how the different dies and stuff work. And of course, safety is first. Have fun and be safe.

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