OAL Gauge Questions

TargetTerror · August 3, 2008, 11:49 AM

I'm going to start working up some loads for my 30-06 and 308 which I hope to pick up soon. I know that consistent bullet measurements are best taken off the ogive, rather than the meplat. I've also read that seating just off the lands is the best way to get good accuracy.

I'd like to get the some tools that make measuring both OAL and distance to the lands easy. I see that Dillon carries the following Stoney Point comparators and OAL gauges:

http://www.dillonprecision.com/conte...let_Comparator
http://www.dillonprecision.com/conte...arator_Inserts
http://www.dillonprecision.com/conte...ll_Length_Gage
http://www.dillonprecision.com/conte..._Modified_Case

If I understand how these tools work, I need all 4 of these items to measure distance to the lands, and OAL of the cartridge, right? Is there anything else I'd need?

wncchester · August 3, 2008, 12:39 PM

"I've also read that seating just off the lands is the best way to get good accuracy."

Yeah. Sure. It's "common wisdom" but wrong more often than not for factory rifles.

Any of the tools and methods for measuring the case length to land contact are good enough. Start your seating maybe .005" off contact and develop your best powder charge. THEN you can work the seating out until you get best accuracy, that will frequently occur in the range of .020" to .050" off the lands.

Seating at the lands mostly works well for competition BR shooters who use very light bullet tension. That's not the way most sport shooters seat, nor should it be.

T-Mac · August 3, 2008, 02:56 PM

Well...you'll need the modified case and the Length guage for sure. Just these tools alone will help quite a bit.

The comparator (w/ inserts) is a nice addition, because bullet tips aren't exactly uniform..thus impacting OAL.
With these, in conjuction with the guage (and modified case), all the guesswork is gone.

To know you are working with factual information helps a lot.

You may be surprised what you find. The assumption that the bullet being closer to the lands gives best accuracy isn't always true.

I have one WIN Mod 70 that likes more "jump" than I'd have ever guessed.

Don2 · August 3, 2008, 07:02 PM

Also look into the RCBS Precision Mic. kit for your caliber.
I use the 223 remington one and I like it.

It will give you the info you need.

http://www.midwayusa.com/eproductpag...297&t=11082005

They have it in 30-06 and 308 as you needed.

Don2

dardascastbullets · August 4, 2008, 12:05 PM

I agree with the other posters about seating depth for sporting rifles. You have to consider the length of the magazine (for bottom-fed actions). If you seat out to the lands in some instances, your cartridges will be too long for the magazine. Winchesters and Remingtons fit into this category. I seated my mid and long range loads (for the .308) 0.002" off the lands. However, I chambered each round by setting it on top of the magazine follower and then closing the bolt slowly - the rounds were too long for the magazine. And I too used to RCBS Precision Mic - I found it to be a very simple tool that has dual duties: case headspace and bullet seating depth. There are several other tools available also. Frustrating isn't it? - So much to choose from!

I trust that this information will help you.

Matt

gun44 · August 5, 2008, 06:54 AM

I usually experiment with different seating depths to determine the best accuracy for any given rifle. Most of the time I have found that just seating off the rifling many times has no effect on the best accuracy. I have one Savage that displays best accuracy with the bullet seated almost so far, as to fall into the case.

August 3, 2008, 11:49 AM	#1
TargetTerror Senior Member Join Date: October 28, 2006 Posts: 424	OAL Gauge Questions I'm going to start working up some loads for my 30-06 and 308 which I hope to pick up soon. I know that consistent bullet measurements are best taken off the ogive, rather than the meplat. I've also read that seating just off the lands is the best way to get good accuracy. I'd like to get the some tools that make measuring both OAL and distance to the lands easy. I see that Dillon carries the following Stoney Point comparators and OAL gauges: http://www.dillonprecision.com/conte...let_Comparator http://www.dillonprecision.com/conte...arator_Inserts http://www.dillonprecision.com/conte...ll_Length_Gage http://www.dillonprecision.com/conte..._Modified_Case If I understand how these tools work, I need all 4 of these items to measure distance to the lands, and OAL of the cartridge, right? Is there anything else I'd need? __________________ Head shots are hard, but nut shots are twice as hard.

August 5, 2008, 06:54 AM	#6
gun44 Senior Member Join Date: August 17, 2007 Location: Georgia Posts: 125	Seating bullets. I usually experiment with different seating depths to determine the best accuracy for any given rifle. Most of the time I have found that just seating off the rifling many times has no effect on the best accuracy. I have one Savage that displays best accuracy with the bullet seated almost so far, as to fall into the case.

August 3, 2008, 12:39 PM	#2
wncchester Senior Member Join Date: December 1, 2002 Posts: 2,832	"I've also read that seating just off the lands is the best way to get good accuracy." Yeah. Sure. It's "common wisdom" but wrong more often than not for factory rifles. Any of the tools and methods for measuring the case length to land contact are good enough. Start your seating maybe .005" off contact and develop your best powder charge. THEN you can work the seating out until you get best accuracy, that will frequently occur in the range of .020" to .050" off the lands. Seating at the lands mostly works well for competition BR shooters who use very light bullet tension. That's not the way most sport shooters seat, nor should it be.

August 3, 2008, 02:56 PM	#3
T-Mac Member Join Date: January 18, 2006 Location: Townsend, MT Posts: 99	Well...you'll need the modified case and the Length guage for sure. Just these tools alone will help quite a bit. The comparator (w/ inserts) is a nice addition, because bullet tips aren't exactly uniform..thus impacting OAL. With these, in conjuction with the guage (and modified case), all the guesswork is gone. To know you are working with factual information helps a lot. You may be surprised what you find. The assumption that the bullet being closer to the lands gives best accuracy isn't always true. I have one WIN Mod 70 that likes more "jump" than I'd have ever guessed.

August 3, 2008, 07:02 PM	#4
Don2 Member Join Date: July 12, 2008 Posts: 21	Also look into the RCBS Precision Mic. kit for your caliber. I use the 223 remington one and I like it. It will give you the info you need. http://www.midwayusa.com/eproductpag...297&t=11082005 They have it in 30-06 and 308 as you needed. Don2

August 4, 2008, 12:05 PM	#5
dardascastbullets Senior Member Join Date: July 20, 2008 Location: Essexville, MI Posts: 164	I agree with the other posters about seating depth for sporting rifles. You have to consider the length of the magazine (for bottom-fed actions). If you seat out to the lands in some instances, your cartridges will be too long for the magazine. Winchesters and Remingtons fit into this category. I seated my mid and long range loads (for the .308) 0.002" off the lands. However, I chambered each round by setting it on top of the magazine follower and then closing the bolt slowly - the rounds were too long for the magazine. And I too used to RCBS Precision Mic - I found it to be a very simple tool that has dual duties: case headspace and bullet seating depth. There are several other tools available also. Frustrating isn't it? - So much to choose from! I trust that this information will help you. Matt