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Head spacing or sprung bolt???

 
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  #1  
Old 08-10-2011, 09:40 PM
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Head spacing or sprung bolt???

OK I've got a major problem or to me it is!! Last hunting season I noticed that some of my brass was cracking (or showing a ring) just above the belt on my 7mmRemMag. I've never noticed this before and have been shooting this load for years. It is 66grs IMR 4350, 140 Nosler Ballistic Tips, 250 CCI Mag primers. My uncle started this load way before I started loading...I just kept up this load as it had performed well. Anyway I thought that my brass was getting worn out, so I replaced it with new Winchester brass the other day, when I shot it today,,dang!! same thing>.I looked it all up and rechecked my dies to be sure that I had resized the new brass correctly, by full sizing I did,,,I even readjusted my dies, still same thing even with only 60grs of powder!! Now, it was not as bad at 60grs but the "RING" was there!! The only thing that I can find on this topic is in an OLD reloading book, there is a picture of the same thing that is happening to me, it says that if it ain't a head space problem then it is a sprung bolt,,,,that the bolt will let it have enough "slack" to cause this???? Can anyone help me out here???? I know that it ain't a head space problem,,,I've redone everything!! Thanks in advance~!!
Shawn aka "Sackett"

Last edited by Sackett; 08-10-2011 at 09:46 PM.
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Old 08-10-2011, 10:40 PM
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Re: Head spacing or sprung bolt???

I would start with some new brass. I would neck the brass up to .30 caliber then partially neck size it back down until it would fit in the chamber with a light crush fit. Hopefully controlling headspace that way would stop the forward flow of brass.


(Actually I would not neck it all the way to .30 caliber but if you do not have a lathe you cannot cut an oddball sized expander mandrel.)
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Old 08-10-2011, 11:31 PM
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Re: Head spacing or sprung bolt???

Quote:
Originally Posted by Sackett View Post
OK I've got a major problem or to me it is!! Last hunting season I noticed that some of my brass was cracking (or showing a ring) just above the belt on my 7mmRemMag. I've never noticed this before and have been shooting this load for years. It is 66grs IMR 4350, 140 Nosler Ballistic Tips, 250 CCI Mag primers. My uncle started this load way before I started loading...I just kept up this load as it had performed well. Anyway I thought that my brass was getting worn out, so I replaced it with new Winchester brass the other day, when I shot it today,,dang!! same thing>.I looked it all up and rechecked my dies to be sure that I had resized the new brass correctly, by full sizing I did,,,I even readjusted my dies, still same thing even with only 60grs of powder!! Now, it was not as bad at 60grs but the "RING" was there!! The only thing that I can find on this topic is in an OLD reloading book, there is a picture of the same thing that is happening to me, it says that if it ain't a head space problem then it is a sprung bolt,,,,that the bolt will let it have enough "slack" to cause this???? Can anyone help me out here???? I know that it ain't a head space problem,,,I've redone everything!! Thanks in advance~!!
Shawn aka "Sackett"
That sounds like case head separation and there are generally 2 main causes.

One is excessive head space. on belted cases head space should be .001 to .0015 Max

If yours is 1 1/2 thousandths or less you are OK.

The other thing that will do this is Over sizing (Much smaller than the chamber) this works the brass
and leads to failure.

To check this measure a sized case from the base to the neck shoulder junction, then do the same
with a fired case. if it is much more than 3 or 4 Thousandths longer then you are over sizing
and need to back of on your dies to the point that you feel just a slight resistance when closing
the bolt.

I Hope this helps to prevent a case head separation.

J E CUSTOM
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Old 08-11-2011, 08:39 PM
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Re: Head spacing or sprung bolt???

Quote:
Originally Posted by eddybo View Post
I would start with some new brass. I would neck the brass up to .30 caliber then partially neck size it back down until it would fit in the chamber with a light crush fit. Hopefully controlling headspace that way would stop the forward flow of brass.


(Actually I would not neck it all the way to .30 caliber but if you do not have a lathe you cannot cut an oddball sized expander mandrel.)
I tried this with a .30caliber mandrel...ran it through the neck, then re-sized it back to 7mm...This was with new Winchester brass...It in fact did help,,,the ring was a slight mark now....I think that I will load 30 rds to hunt with this year, as season opens in 4 days!! I will only use this gun for my long range stands and use my .257Roberts a lot more this year, then when season is over I will send it off somewhere to be re-barreled...Never done this before and I can use this as an excuse to spend the money...not like most of you guys, but for a serious hunter, and shooter I think it will be way better than anything I've ever had...Any advise would be taken well,,,I HOPE to spend $700.00 to $800.00 range...I have a Remington Model 700 Classic 7mmRemMag, Remington Synthetic stock which was glass bedded and floated about 15 years ago!!
Thanks for your help!!
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  #5  
Old 08-12-2011, 12:51 PM
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Re: Head spacing or sprung bolt???

Get it rechambered in 338Edge. Just to have something different.
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  #6  
Old 08-12-2011, 01:39 PM
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Re: Head spacing or sprung bolt???

" if it ain't a head space problem then it is a sprung bolt,,,,that the bolt will let it have enough "slack" to cause this???? "

Well, a 'sprung bolt' IS a head space problem as surely as a chamber that is bored to deeply; after all, the bolt face is simply the back of the chamber.

No matter what causes it, excess chamber 'headspace' is a problem simply because it allows the brass to stretch too much. Actually, excess headspace means nothing to a reloader, or shouldn't, because we can easily adjust our FLsizer to match what ever the chamber is. But, if it's long and we insist on resizing to factory length each time we can get into a seperation situation very quickly.

I can't see your rig or fired cases but I'd bet you are shoulving your case shoulders back too far and creating the slop that amounts to excess headspace no matter what that is. Easiest way to set an FL die properly is to have something like Hornady's case gage tools to use with your dial caliper; just set the die to move the sized shoulders back to, or a thou or so shorter than, the fired location and all will be well.
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Old 08-12-2011, 04:04 PM
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Re: Head spacing or sprung bolt???

Quote:
Originally Posted by Limbic View Post
Get it rechambered in 338Edge. Just to have something different.
Man your just trying to start problems aint ya. Come see me some time and lets do some shooting. I am finally well, just getting back to shooting a bit. I will miss the BC match this month because I am going to shoot an antelope, but if they have it nect month I will probably be there. BTW call me about a hunt if you can break away a few days first of December.
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