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Old September 20, 2009, 09:00 PM   #1
Hair Trigger Coastie
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7MM Case Crunch

This is my first time posting, but I have something that is quite baffling, so I registered and here I am.

I am reloading for a 7mm Rem Mag and I have a sundry of cases to try and work up. However, I am having a bit of trouble with the Federal cases. I am working these up the same as any other case (smoked, sized, trimmed, deburred etc.) However, once I get to the seating and crimping, the case neck tries to retreat into the case shoulder. I am using a light taper crimp, but through experimentation, the first little bit of pressure on the neck and it starts to move. Annealing does not help.

So I leave it to you'ins (y'all plus 3) to mull it over and give me some idea of where the SNAFU is. Keep in mind, these Feds are once fired. I have been working of Winchesters that have been thrice fired, with nary a hitch. The only thing I do not have the tools to measure it the actual case neck thickness, though the Wins and Feds are within 2 grains of weighing the same.

Take a look at the pics and let me know what you think.

HTCoastie
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Old September 21, 2009, 01:34 AM   #2
Big G
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Go back, if you have not already and try your Winchester cases again to see if it is still working okay. Something may be stuck in the die, take it out and shine a light in it to check it good.If that is not it, looks like either the brass is longer or the die has been readjusted.You say you can not measure the case neck thickness? What are you useing to measure the overall length of the loaded round.
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Old September 21, 2009, 02:19 AM   #3
Shoney
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Hair Trigger Coastie

WELCOME TO TFL!!!!!!!!

On rifle cartridges, once the case has been sized and trimmed, you need only seat the bullet to the proper depth. If you have not been camphering the inside of the neck, the bullet can push the neck into the shoulder. Usually the neck tension from the sizing operation is enough to hold the bullet in place without applying a crimp.

However, it appears from the pictures that you are applying way too much crimp. The crimp die must be set with a case at top dead center (TDC) of the ram, so that it just kisses the case mouth. I screw mine in hand tight, then lock the die down. I then screw the seating stem down and set the bullet depth.

Remember that on some presses the ram reaches TDC then lowers a bit as the press "cams over". If you set up at the cammed over position, you may be pushing the case further in than at the point where it is cammed.

Hope this helps.

Good Shooting!
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Old September 21, 2009, 08:48 AM   #4
Big G
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He may very well need to crimp if he is shooting a semi-auto or a lever gun. On single shots or bolt actions it is ok not to crimp.
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Old September 21, 2009, 10:06 AM   #5
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I've never crimped any rifle cases because the neck tension has been sufficient. If you're loading for an auto or lever, get RCBS Small Base dies. Further, I don't use Federal brass as I've found it much softer.
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Old September 21, 2009, 12:18 PM   #6
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Those cases do NOT appear to have been trimmed OR chamfered. They're probably longer than the win cases that worked.

I agree, there's no reason to crimp those rounds. There are a few semi-auto 7 mags, but I doubt they would need to be crimped for those either.
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Old September 21, 2009, 02:28 PM   #7
plainsman456
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I would check the dies to see if there is anything in them.Then back them out and try it again watching as you seat them deeper.You should not need to crimp a 7mag.Let us know when you get it fixed.Good Luck
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Old September 21, 2009, 05:28 PM   #8
Hair Trigger Coastie
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Though they look a bit dingy, the cases are trimmed, deburred and chamfered. I am using RCBS dies in a Rock Chucker Supreme. According to Sierra, I am actually trimming the cases .010 shorter than max, so I "should" be good there. As far as OAL I am letting the rifle chamber dictate the length at a calipered 3.350 vs 3.290 (Sierra).

I will check the "Cam Over", but the case was starting to deform on the slightest pressure. I would ram up, check and then slightly adjust the die. Seems anal, but I did that for about 30 minutes on three or for different cases, with Winchesters thrown in for an experiment "control group."

The taper crimp is very light. The expander ball widens the neck too much for my liking, but it is what it is. So I crimp enough to compensate for the expander ball and just enough pressure to hold the bullet.

I am calling RCBS tomorrow to pick their brains. I may swap a buddy for his Hornady Dies and see what happens when I set it up. That way I can rule out the operator, hopefully.

Thanks for all of your input!
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Old September 21, 2009, 07:04 PM   #9
longranger
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If you insist on crimping do it in a seperate operation.Seat all bullets to desired OAL then back out the seater plug reset the die for the desired crimp.If you are seating and crimping in the same operation that is what is happening not an uncommon problem.
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Old September 22, 2009, 01:21 AM   #10
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Quote:
If you insist on crimping do it in a seperate operation.Seat all bullets to desired OAL then back out the seater plug reset the die for the desired crimp.If you are seating and crimping in the same operation that is what is happening not an uncommon problem.
^What he said.^

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Old September 22, 2009, 12:27 PM   #11
ojibweindian
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Never heard of taper crimping a bottleneck rifle cartridge. Roll crimping at the cannelure, yes.

Have you tried backing off your seating die a few turns?
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Old September 23, 2009, 04:47 PM   #12
Kawabuggy
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For those who are stating that rifle rounds do not have to be crimped-let me just say that there is a school of thought, and some testing to prove-that crimping does improve accuracy. There was a test done wherein they tested the exact same loads, half of the rounds crimped, and the other half not crimped. What they found was that the SD, and ES were smaller with the crimped rounds, in addition to the crimped rounds producing better accuracy. This "test" was administered over 3 different calibers, using different bullet weights in each caliber, and the tests all proved that in each and every case the crimped rounds were more accurate across the board. If I remember correctly the figure given was "10% increased accuracy over non-crimped rounds".

If crimping has the potential to make more accurate rounds, why not?

In regards to the OP's question, back the seating die out a full turn and try again with the Federal brass. If you want to crimp, as mentioned above, use a LEE FACTORY CRIMP DIE (LFCD) and do it as an additional step after the bullets are seated to your chosen COAL.
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Old September 23, 2009, 04:56 PM   #13
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agreeing with some previous posts.... i believe the seating die is set too low... raise the entire die and lower the bullet seater.
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Old September 23, 2009, 06:05 PM   #14
Hair Trigger Coastie
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OK. I fixed it. Mica. $2.50 fix. Plus I had to chamfer the case mouth razor thin. DUH! However, one bandsaw and two experimental cases later revealed the brass was thinner at the neck than the Winchesters.

As far as the crimping goes, there is two ways to crimp: Taper and Roll. Roll crimp is the preferred method for revolvers and heavy kickers. Taper crimp just puts a slight uniform "squeeze" on the bullet, just enough to keep it seated, which is what is preferred on firearms that seat off the case mouth. On the RCBS dies I have, the expander ball widens the mouth just enough that the bullet NEEDS the squeeze or the bullet sinks away. For your Naysayers, I shoot sub-MOA out of ALL of my scoped rifles (.223, 25-06, 6.5x55, 30-06). My .223 makes ONE hole and yes, the rounds are taper crimped. The 7mm belongs to a friend of mine, but I still want to give it close to the same quality I give my rifles.

Thanks for your help. It got me thinking in the right direction.

HTC

Last edited by Hair Trigger Coastie; September 23, 2009 at 09:30 PM.
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