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New 6.5 Idea

 
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  #50  
Old 02-05-2013, 12:36 PM
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Re: New 6.5 Idea

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Originally Posted by 7mmRHB View Post
Daveinjax, this is an overview of the process to form shortened cases.
The steps needed to make the 6.5 BPX from 6.5 x284 Lapua brass. Pushing the shoulder back .250 and lengthening the neck to .320.



1. Square case heads.
2. uniform primer pockets.
3. Deburr and chamfer flash hole.
4. Anneal shoulder and neck.
5. Lube inside of the neck, then expand necks to .290 with expander mandrel.
6. Lube the outside of the case and run it into Form Die #1.
7. Lube the new neck area again and run the case into Form Die #2.
8. Clean the cases inside and out.
9. Trim cases to 1.965 length.
10. Chamfer inside case mouth.
11. Aneal case necks.
12. Expand case necks with a .269 Expander mandrel.
13. Ream inside necks with a .280 reamer.
14. Expand w/ 7mm mandrel and outside neck turn to .014 neck thickness.
15. Chamfer outside of necks and polish inside with 0000 steel wool.
16. Lube cases inside and out, then run them into Form Die #3, 6.5 mm, with the expander ball attached.
17. Clean the lube off of the outside of the cases.
18. Expand neck to fir 6.5mm neck turn mandrel.
19. Turn necks to .0125 thickness. (.289 neck diameter with 140 Berger seated)
20. Chamfer necks inside and out.
21. Polish cases inside and out.
22. Fireform brass using 140 grain bullet with 40 gr. Varget.
23. Reprep brass to a trim length of 1.960

The 6.5 BPX is an improved cartridge design with minimum taper ( .0125 ) and 35* shoulder.

This was my original work list that has been changed a few times but gives an idea of the difficulty in shortening cases!! ---- 7mmRHB
I was looking over your forming process and had some questions.
1- How do you go about squaring the case heads? Never heard of this before.
2- Why do you anneal before working the brass. Isn't the Lapau brass already annealed?
3- I'm guessing you expand the necks out to .290 to make setting the shoulders back easier?
4- Why do you trim the brass before the final sizing and fire forming?
5- You expand the necks to .269 and use a .280 reamer?
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  #51  
Old 02-05-2013, 04:56 PM
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Re: New 6.5 Idea

Montana, good questions, I was surprised when no one commented on the list.

1-- Turn case backwards in a Wilson Case trimmer and make a light cut until you're at least a bit past the primer pocket. There are no brands of brass that are square or perpendicular as the come from the manufacture.

2-- I always thought that Lapua brass was annealed but the first few necks popped the full length of the neck when easing the tapered expander through. The shoulder needs to be annealed further back anyway so it's no big deal to do it. The case needs to be expanded so that the neck shoulder junction starts to get the crease ironed out.

3-- The necks are a half inch long at this point so it's easier to get rid of it at this point so it's out of the road.

4-- I expand with the smaller mandrel to push some material to the outside of the neck for neck turning. there is about .030 thickness in the necks at this point so you need to get rid of brass inside and out . If you try to take it all out of the inside, the neck is uneven enough that you can't get it to clean up at .014"

I hope that answered your questions. ---- 7mmRHB
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  #52  
Old 02-05-2013, 05:11 PM
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Re: New 6.5 Idea

Thanks Grit, I'm glad you think there might be some potential in this little cartridge. I'll see what I can do about a range day if we ever get the weather to warm up?

22 CAN ----H. thanks for putting up the pics of of your new shooter. Thanks also for the endorsement. Good parts, nice paint. That was fun build. ---- 7mmRHB
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  #53  
Old 02-05-2013, 05:38 PM
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Re: New 6.5 Idea

Quote:
Quote:
Originally Posted by 7mmRHB View Post
Montana, good questions, I was surprised when no one commented on the list.

1-- Turn case backwards in a Wilson Case trimmer and make a light cut until you're at least a bit past the primer pocket. There are no brands of brass that are square or perpendicular as the come from the manufacture.


I hope that answered your questions. ---- 7mmRHB
I actually started doing this unintentionally once while multi-tasking. Thought I was doing a bad thing

Thanks, for answers. I've been thinking on a similar project to make a cartridge able to fit in the standard Howa action. I've been thinking of making a forming die with a double radius shoulder, like a Weatherby but softer radius's, to make the flow of brass a little easier. Also thinking of having it nitrided for less friction. It's been an interesting and informative thread.
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  #54  
Old 02-06-2013, 11:33 AM
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Re: New 6.5 Idea

Montana, I don't know if your radius method would work but it is interesting. I suspect the load forces might be to great and cause the body to buckle just below the shoulder. The only way to know is to try it. --- 7mmRHB
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  #55  
Old 02-07-2013, 12:30 PM
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Re: New 6.5 Idea

Sounds like an interesting cartridge and something that a lot of tactical shooters would be interested in. Looking forward to your test results. Keep us posted.
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  #56  
Old 02-07-2013, 01:03 PM
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Re: New 6.5 Idea

We thought that also, we kick the name around 6.5 Fat Tac for a little while. Now if we were not such cold weather boobs we be out seeing if it it does what we think it might, we have been stuck in the low 30's and have work that keeps getting in the way. Hopefuly we will get out shortly and get at least some velocity readings.

Thanks for your interest in our project, posting what we are doing has been fun.
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