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Old April 8, 2007, 01:57 PM   #1
shepheard
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how to set bullet depth

I am new to the world of reloading,in fact so new all I have done so far is extensive readind of various manuals and talk forums. It is my understanding that a 7mm mag should be crimped.If so how would you be able to customize seating depths to be x distance from the lands.My hornady manuel has a trim lenght of 2.490. Bullets have a cannelure at a set spot,wouldn't that dictate the distance of ogive to lands.Your input is greatly apreciated.
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Old April 8, 2007, 02:08 PM   #2
Jim Watson
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I don't crimp rifle bullets except for tubular magazine lever actions. From what do you understand a 7mm magnum should be crimped?

I try to avoid cannelured rifle bullets because I do not see how they can apply it without hurting accuracy.

I seat Sierra Matchkings for a short jump to the rifling, I seat JLK or Berger VLDs into the rifling, I seat hunting bullets to magazine length, checked to be sure they are off the rifling.
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Old April 8, 2007, 02:23 PM   #3
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I seat 1 die turn from the lands, or about 1/14". Do this by inserting a bullet in to an empty case. Insert cartridge into rifle and slowly close the bolt, then slowly extract. The bullet has been pushed into the case by touching the lands. Put this into you press, turn the seating die down until it touches, remove the cartridge and turn the die one full turn. Has worked very well for accuracy. Yes, have to check that your magazine can handle them.

Am with Jim W .. I never crimp except for tubular mag rifles either.

Have not noticed any decrease in accuracy shooting bullets with a cannelure. But, agree there has to some effect ... probably not enough to affect anyone except, perhaps, the benchrest, long range shooter. Would be interested in other input on this.
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Old April 8, 2007, 09:19 PM   #4
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trim and COAL lengths in mauals are for reference only--your results may vary
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Old April 8, 2007, 10:03 PM   #5
mrawesome22
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Take a empty case. Cut a vertical slit in the neck, barely into the shoulder, with a hacksaw. Barely seat the bullet you want to use in this case with your hands. Chamber this round in your rifle. Eject it with your hand covering the ejection port. Take it out and measure it from base to tip with your calipers. This will give you MAX OAL (over all length) for that bullet. In other words, this bullet is touching the rifling. Now you can experiment with different seating depths. I've found that my rifle usually gives best accuracy .030" away from the rifling. But you'll just have to experiment as to what shoots the best out of your gun. This method works very well and you don't have to waste money on a Stoney Point guage

The guys are right, no need for a crimp.
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Old April 8, 2007, 10:27 PM   #6
Bullet94
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Quote:
mrawesome22
Take a empty case. Cut a vertical slit in the neck, barely into the shoulder, with a hacksaw. Barely seat the bullet you want to use in this case with your hands. Chamber this round in your rifle. Eject it with your hand covering the ejection port. Take it out and measure it from base to tip with your calipers. This will give you MAX OAL (over all length) for that bullet. In other words, this bullet is touching the rifling.
Are you sure this would give you the MAX OAL? I thought the MAX OAL would be Jam length (into the lands).

If you’re going to go longer than the reloading manuals listed OAL. I would recommend you get a bullet comparator to measure from the ogive. Measurements made from the bullet tip will vary. Here is a link to the one I like. –

http://www.sinclairintl.com/cgi-bin/...600&type=store
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Old April 8, 2007, 10:47 PM   #7
shepheard
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I really apreciate all of your info.From what I understand auto loaders,tube mag and rifles with a good deal of recoil should be crimped.My rifle is a ruger m77.Maybe I miss understood what I was reading.Again thanx much for all your input.
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Old April 16, 2007, 05:56 AM   #8
U.S.SFC_RET
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Bullet94: mrawesome22 is actually talking about how the ogive touches the lands. He is most likely using the total bullet measurement as a reference because of the ogive touching the lands.
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Old April 16, 2007, 06:58 AM   #9
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For the sake of clarity, I think you are asking about overall length. Seating depth refers to how deeply the base of the bullet is inside the case.
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Old April 16, 2007, 08:44 AM   #10
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This has all been discussed in another thread. Search for "Bullet Seating Question" by Dirty Habit.
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Old June 20, 2010, 11:22 PM   #11
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thread resurrection!!

Can't accuse me of not searching previous past posts! lol

From mrawesome22's post:
Quote:
Cut a vertical slit in the neck, barely into the shoulder, with a hacksaw.
What purpose does cutting the slit in the neck accomplish? It seems to me you would be able to do this without the slit.
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Old June 21, 2010, 11:26 AM   #12
brickeyee
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What purpose does cutting the slit in the neck accomplish? It seems to me you would be able to do this without the slit.
It reduces the force needed to move the bullet into the shell.

Without the slit the bullet can actually start to engrave onto the lands as it is pushed in to the case, messing up the measurement you are trying to take.

A similar thing is done for the commercial cases for the hornady tool.

Along with drilling and taping the case head they use an oversize expander to open up the neck so the bullet is a relatively loose fit.

You can easily feel when the bullet touches the rifling.

If you use to much force, the bullet can actually stick in the rifling.
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Old June 21, 2010, 11:42 AM   #13
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I check every rifle I get to find out what the maximum seat depth is for whatever given bullet I use.

I purchased a Sinclair Bullet Seating Depth Tool:
http://www.sinclairintl.com/.aspx/pi...ing_Depth_Tool

And

Hornady's Lock and Load Comparator that bolts onto your calipers:
http://www.sinclairintl.com/.aspx/pi..._w__14_Inserts

I make two measurements and add them together:

1. Take a measurement with the Sinclair Tool. You drop the bullet in the chamber and set one collar, then take the bullet out and drop a sized case into the chamber and set the other collar. (then take you measurement to the outside of the collars).
2. Measure the ogive length of the bullet with the Hornady tool.
3. Add those two numbers from the two different tools together. That is your length to the rifling.
4. When you seat your bullets you simply keep dialing your seater down until you hit that number (minus what ever jump you want). This is measured on the Hornady tool.

This, in my opinion is the most foolproof, easiest method to attain the most accurate results. No cutting cases (not that it isn't a viable method), but can be problematic getting adequate tension on the bullet without it falling into the case or getting the bullet stuck on the rifling and pulling it out of the case.

If you need further instructions or pictures let me know.
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Old June 21, 2010, 11:57 AM   #14
wncchester
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"It is my understanding that a 7mm mag should be crimped."

Not true.

As a noob, just stick with book OAL.

It's not necessary to split a case neck to find the maximum OAL to the lands. Simply crimping a fired case neck lightly with pliers works fine to retain a bullet for a slip fit.
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Old June 21, 2010, 09:37 PM   #15
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great information everyone, thanks!
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