Fire forming new br...
 
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Fire forming new brass

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(@gabry78)
Posts: 3
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Hi everybody! About to finally put my hands on my semi-custom built (sako 75 action/ bartlein barrel/ AG composites stock) in 6,5 Swed. Purchased a 200 batch of brand new Lapua brass. Don’t wanna screw up the fire forming process in order to have correct measurments for the shoulder set back procedure and full lenght die setup. My questions are:1-shoud i fire the new brass with a mild load and jamming the lands? 2-should i expect, in this way, to have the brass matching precisely the chamber after 1/2 firings? Have been following Erik’s forum and videos and this appears to be one of the solutions to avoid brass growth in both directions (bad) instead of only forward (good).. any help/ suggestion is more than welcome. Thanks

Gabriele

 
Posted : 01/24/2023 5:00 PM
(@charles-wachter)
Posts: 565
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If you haven't watched Erik's PRS/F Class loading series do this first.  https://www.shootsmallgroups.com/community/prs-reloading-series/

I am not an expert like Erik but this is what I do.  I remove the ejector and firing pin from the bolt.  I then jam a bullet and record this measurement.  Then I move the bullet into the case .001" at a time to find the spot where the bolt will drop on it's own.  Erik calls this touch.  Record this measurement.  Reinstall the firing pin but leave the ejector out.  I seat the bullet a few thousandths longer than touch. I have a lot of experience with this particular load so I know I'm not going to cause excess pressure so I don't reduce my load.  In your case I would recommend you reduce your load.  So now when you close your bolt the case is against the bolt face and the bullet is against the lands.  Most the time when I do this the case will form on the first shot.  But, I know what my fire formed case length should be.  You may not.  So you may have to do this once more.

Edit:  I added the link to the PRS loading series.

This post was modified 1 week ago by charles wachter
 
Posted : 01/24/2023 7:11 PM
(@david-salsedo)
Posts: 35
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Great advice Charles

 
Posted : 01/24/2023 7:50 PM
(@gabry78)
Posts: 3
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Topic starter
 

Thanks a lot Charles! Will watch Erik’s video once more and follow your advice. Sako bolt has a mechanical ejector, so one step less..

Gabriele

 
Posted : 01/24/2023 8:02 PM
(@gabry78)
Posts: 3
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Topic starter
 

Any relevant difference in this process when fire forming new brass in belted magnum cartridges (7RM, .300 win mag)?

Gabriele

 
Posted : 01/26/2023 3:58 AM

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