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Reloading Techniques For Reloading


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Flattened primers?

 
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  #8  
Old 11-01-2013, 10:44 AM
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Re: Flattened primers?

I have a 7mm rm like Gunpour. It has a generous chamber so I neck sise then fl sise when the bolt stats to close stiffly.
But, if you are not having those problems with all of your brass sort them into good primer and flattened primer piles. Then trim all to the same length and weight them, you may just have a batch of brass with thicker walls than the rest
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  #9  
Old 11-01-2013, 11:01 AM
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Re: Flattened primers?

Never thought of that, I'll try it.
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  #10  
Old 11-01-2013, 12:10 PM
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Location: Tucson Az
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Re: Flattened primers?

I should have asked this earlier. Did your once fired cases exibit flattened primers too? Or did you acquire them already fired?

I encountered a 300 win that had a great deal of headspace. Didn't see any symptoms because the belt kept the case in place during firing allowing the shoulder to move forward. Never knew till I tried to fit some of the sized cases into a different 300 win mag.

To make a false shoulder you need a larger sizer ball to expand the neck of the case. You would use a 308 sizer ball. After the entire neck has been expanded run the case back into your 7mm Dakota die reducing some of the neck diameter back to 7mm to a point where the bolt could be closed but with some resistance. The false shoulder keeps the case head against the bolt face and will allow the case to stretch and fill up the shape of the larger chamber.

It would be interesting to fireform one case then section it to study the area just in front of the web to see if it was stretched to a narrower dimension. If you found that to be the situation, your chamber is too long to use safely.

You could section a fired case and look at the area in front in of the web as well.

Probably the best idea is to have a gunsmith reduce the headspace of the rifle. It isn't that hard and doesn't require a reamer.

Let us know what you end up doing.

Ross
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  #11  
Old 11-01-2013, 12:46 PM
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Re: Flattened primers?

Quote:
Originally Posted by AZShooter View Post

It would be interesting to fireform one case then section it to study the area just in front of the web to see if it was stretched to a narrower dimension. If you found that to be the situation, your chamber is too long to use safely.

Probably the best idea is to have a gunsmith reduce the headspace of the rifle. It isn't that hard and doesn't require a reamer.
I second the above! You can also try the paperclip trick to see if you have case thinning. This article has a pretty practical explanation of looking for signs of web thinning. The Rifleman's Journal: Reloading: Case Head Separations
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  #12  
Old 11-01-2013, 02:14 PM
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Re: Flattened primers?

I prefer the belted mag case.
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  #13  
Old 11-01-2013, 02:15 PM
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Re: Flattened primers?

Great articles thanks. Yes the brass I received with the rifle were already once fired so I didn't see any primer flatning until I started shooting the new brass. How does the gunsmith reduce headspace? Shims?
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  #14  
Old 11-01-2013, 03:01 PM
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Re: Flattened primers?

How to correct excessive headspace?

The gunsmith must make some measurements. A headspace go and no go gauge is used if available. If not the measurements should be able to be accomplished by comparing unsized fired brass vs virgin brass.


The barrel is unscrewed from the reciever using a barrel vise and an action wrench. Then the barrel is centered in a lathe chuck. Metal is machined off the end of the chamber. The same amount of metal is machined from the shoulder moving it forward. If there is an extractor notch in the end of the barrel, it has be indexed and machined deeper for bolt face clearance. If any of these cuts remove more metal than required then a reamer must be used to cut the proper chamber depth to achieve proper headspace.

How do I know this? I did my first barrel with crude measurement devices and cut the chamber too deeply (same as yours, excessive headspace). I then sopme off the end of the barrel to shorten the chamber length and over did that. I then ran in the chamber reamer and went too deep again! I eventually got it. Later on I purchased some tooling to help me make the proper chamber the first time. Nothing like screwing up to truly understand the process.

Basically the entire barrel is set deeper into the reciever with the end result being a shorter chamber.
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