Am I doing Something Wrong?

[Historian]

I recently purchased a Hornady OAL guage to measure the chamber on my .223 Bushmaster Varminter. After using it several times and getting the same result, I determined the the bullet jump on this rifle is nearly 1"??? Am I doing something wrong? The rifle is very accurate but this seems like it should be way too long. Thanks.

Historian

 

[brickeyee]

That seems large, but wear (and it would take a LOT of rounds to chew up that much rifling) could be there, or originally very long throated (seems awfully long though)..

How old is the barrel?

Did you check the bullet diameter with a micrometer?

Are you measuring to the tip[ of the bullet an not the ogive?

Correct insert for ogive measurement?

Did you deduct for the ogive units length?

 

[243winxb]

Am I doing something wrong?

Let me guess, Yes.

 

[jcwit]

Sumthen ain't right for sure!

 

[NeuseRvrRat]

unless you're loading it single-shot style, all you can do is just load it to magazine length and let it ride.

 

[rikman]

You should be measuring cartridge oal, which will be your chamber length... With "that" bullet. Not measuring bullet jump. You set the jump by adjusting the cartridge length from head to ogive.


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[rikman]

Only reason to do this is in an AR is for long heavy bullets,ie 80gr Amax for single loading due to longer length, >2.260".


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[243winxb]

I recently purchased a Hornady OAL guage to measure the chamber

This chamber measurement is from the head to the datum. The datum is on the shoulder, being .330" in diameter. This distance is NOT the OAL. The OAL is from head to meplat/tip of the bullet nose. Its also possible to measure to the ogive of the bullet using this tool. http://www.saami.org/PubResources/CC_Drawings/Rifle/223%20Remington.pdf