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#6887323 - 09/14/17 12:54 PM different headspace measurements on fired brass
TackDriver Offline
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Registered: 05/02/14
Posts: 599
I felt several chamberings that felt real snug on the .308 and fired all the loaded rounds. When I measured the headspace on the fired brass ( to bump .002" on the Redding body die ) and there was a variance of .003" I have not experienced that before and so I put the whole batch of brass through the body die and bumped back .002" and neck sized for the next loading.

What would be the issue of the .001" - .003" variance between fired brass? confused2


Edited by TackDriver (09/14/17 12:56 PM)

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#6887334 - 09/14/17 01:00 PM Re: different headspace measurements on fired brass [Re: TackDriver]
ChadTRG42 Offline
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Registered: 09/16/09
Posts: 11040
Loc: Lewisville, TX
Is it all the same head stamp (same brand and lot)? It could be a small variation from piece to piece. It could also be a slight variation on the case head. I've had some pieces of brass that had the rim ever so slightly bent, and would throw off a head space measurement by a few thousandths.

I've seen .001"-.002" variation. I size to the shortest one. I'm not worried about 1 or 2 thou, though. Size it to the shortest piece you are measuring, and call it good. Just chamber check your brass after sizing to make sure it chambers smooth.
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#6887355 - 09/14/17 01:24 PM Re: different headspace measurements on fired brass [Re: TackDriver]
patriot07 Online   content
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Registered: 11/06/11
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I'm new to the reloading game, but I will say that from an engineering standpoint, .001" is just absolutely nothing. It's hard to control anything to that level. Some of this reloading equipment is really capable of top-notch precision, but it's very difficult to understand how small that type of distance really is. I'm amazed that you guys can control this stuff as well as you do.

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#6887378 - 09/14/17 01:52 PM Re: different headspace measurements on fired brass [Re: TackDriver]
ChadTRG42 Offline
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Registered: 09/16/09
Posts: 11040
Loc: Lewisville, TX
If you think about, the typical max to min headspace on a go, no-go gauge is .006" (sometimes .007"). A few thousands difference in the head space area is VERY important.
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#6887400 - 09/14/17 02:22 PM Re: different headspace measurements on fired brass [Re: TackDriver]
patriot07 Online   content
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I believe it. It's just very impressive to me that they've created affordable tools that can control dimensions to that type of precision.

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#6887465 - 09/14/17 03:22 PM Re: different headspace measurements on fired brass [Re: ChadTRG42]
TackDriver Offline
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Registered: 05/02/14
Posts: 599
Originally Posted By: ChadTRG42
Is it all the same head stamp (same brand and lot)? It could be a small variation from piece to piece. It could also be a slight variation on the case head. I've had some pieces of brass that had the rim ever so slightly bent, and would throw off a head space measurement by a few thousandths.

I've seen .001"-.002" variation. I size to the shortest one. I'm not worried about 1 or 2 thou, though. Size it to the shortest piece you are measuring, and call it good. Just chamber check your brass after sizing to make sure it chambers smooth.


Yes Chad, its all the same headstamp, its Lapua brass, all the same lot, fired the same number of times. Fired 6 X's. Most are .001 to .002 off, a few are .003"

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#6887550 - 09/14/17 04:15 PM Re: different headspace measurements on fired brass [Re: TackDriver]
ChadTRG42 Offline
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Registered: 09/16/09
Posts: 11040
Loc: Lewisville, TX
Well, after so many firings, you can get some brass flow in various areas. I'd call it good if it was within .002", honestly.
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#6887980 - 09/14/17 10:53 PM Re: different headspace measurements on fired brass [Re: patriot07]
cblackall Offline
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Registered: 05/12/16
Posts: 185
Loc: Lewisville, TX
Originally Posted By: patriot07
I'm new to the reloading game, but I will say that from an engineering standpoint, .001" is just absolutely nothing. It's hard to control anything to that level. Some of this reloading equipment is really capable of top-notch precision, but it's very difficult to understand how small that type of distance really is. I'm amazed that you guys can control this stuff as well as you do.


I understand where you're coming from. I've been reloading for nearly 20 years, and 10-20 thousandths of an inch doesn't sound or look like much of anything. But when you're dealing with firearms and ammunition, it might as well be miles. It's amazing how much difference a couple thousandths will make, be it a round chambering or not or the difference in safe or unsafe.

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#6887987 - 09/14/17 11:02 PM Re: different headspace measurements on fired brass [Re: TackDriver]
TackDriver Offline
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Registered: 05/02/14
Posts: 599
Thanks Chad.

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#6887997 - 09/14/17 11:16 PM Re: different headspace measurements on fired brass [Re: TackDriver]
Smokey Bear Offline
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Registered: 05/11/17
Posts: 167
Loc: Texas
TD, have you annealed? That would be by first thought. After several firings the malleability of the brass will not be as consistent and you can get differences in spring back after sizing. One other thing to check if your are loading up near max, particularly if you have been shooting in hot weather. A slight ejector swipe can give you inconsistent measurements depending if your caliper is on the mark or not. A few thousands isn't much but examining the case head through a magnifying glass will allow you to see it.
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#6888125 - 09/15/17 07:56 AM Re: different headspace measurements on fired brass [Re: Smokey Bear]
TackDriver Offline
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Registered: 05/02/14
Posts: 599
Originally Posted By: Smokey Bear
TD, have you annealed? That would be by first thought. After several firings the malleability of the brass will not be as consistent and you can get differences in spring back after sizing. One other thing to check if your are loading up near max, particularly if you have been shooting in hot weather. A slight ejector swipe can give you inconsistent measurements depending if your caliper is on the mark or not. A few thousands isn't much but examining the case head through a magnifying glass will allow you to see it.


Yes, I annealed prior to firing them and they were under max load with 44.4 grains of Varget at 2,770 fps with no pressure signs at all, no ejector swipe. The weather was cooler this time out at 75 degrees compared to 90 prior to that. Even did all case prep prior to firing. That bugs me.





Edited by TackDriver (09/15/17 07:57 AM)

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#6888195 - 09/15/17 08:59 AM Re: different headspace measurements on fired brass [Re: TackDriver]
FiremanJG Offline
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Registered: 12/16/08
Posts: 21142
Loc: Wolfe City, TX
Were you measuring head space on a fired primer, or after decapping?

If with a fired primer in the pocket, and if there is any flow back, on the primer, around the firing pin strike it will throw off your head space measurement.
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#6888216 - 09/15/17 09:21 AM Re: different headspace measurements on fired brass [Re: TackDriver]
RiverRider Offline
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Registered: 11/11/07
Posts: 7109
Loc: Wise Co.
One other idea...if this is new brass, it may not yet be fully fireformed to your chamber.
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#6888225 - 09/15/17 09:26 AM Re: different headspace measurements on fired brass [Re: FiremanJG]
TackDriver Offline
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Registered: 05/02/14
Posts: 599
Originally Posted By: FiremanJG
Were you measuring head space on a fired primer, or after decapping?

If with a fired primer in the pocket, and if there is any flow back, on the primer, around the firing pin strike it will throw off your head space measurement.


I used the Lee decapper first and decapped all primers and measured after.

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#6888226 - 09/15/17 09:27 AM Re: different headspace measurements on fired brass [Re: RiverRider]
TackDriver Offline
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Registered: 05/02/14
Posts: 599
Originally Posted By: RiverRider
One other idea...if this is new brass, it may not yet be fully fireformed to your chamber.


Brass is on 6th firing.

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