Oal gauge suggestion

  • Thread starter Deleted member 107796
  • Start date
D

Deleted member 107796

Guest
I've never used a gauge to determine how far off the lands my handloads are, I've just loaded to max oal and adjust from there. I have standard and magnum calibers. Is there a good gauge that can easily accommodate many calibers and is not the most expensive? Thanks
 

SealT5

Well-Known Member
Joined
Jan 11, 2016
Messages
872


The link above is the technique I use and find that it provides very consistent and accurate results. Hornady makes a tool that uses a modified case. I couldn’t get it to read accurately but many have had good success.

You will need a Bullet Comparator set to in order to take measurements off of the bullet Ogive. Measuring from the tip of the bullet will be very inconsistent
 

RegionRat

Well-Known Member
Joined
Nov 11, 2012
Messages
60
Location
Redondo Beach, CA
Thanks guys, exactly what I'm looking for.
When you think you really know the reference length to get a jam, be patient because the slope on the land leade can cause lots of uncertainty. I will suggest you sacrifice one bullet and case by loading to the reference length and test it to verify it doesn't get marked up by the lands, then buff it up and try to go 0.010" longer and jam it on purpose to be sure. You should be able to use the same bullet by using a kinetic puller to either make it longer or start it over.

Often, you may find that the errors in the measurement process are larger than you think, and when you actually load on a closed bolt with a dummy round, you learn the reality. I still think you should own the gages and do your best to track the wear on your lands, but don't get discouraged by how uncertain the process can be.
 

elf

Well-Known Member
Joined
Nov 26, 2017
Messages
329
I have tried them all and I like the method described by Alex in the video. Agree, the Hornady (formerly Stony Point) tool is easy to use. Always clean the bullet with 0000 steel wool first (makes the land marks easy to see); and take 5 or so measurements and average those. Make a dummy round with your final measurement, and you should see the marks.
 

YZ-80

Well-Known Member
Joined
Feb 20, 2019
Messages
1,235
Location
Maryland
When you think you really know the reference length to get a jam, be patient because the slope on the land leade can cause lots of uncertainty..........and do your best to track the wear on your lands, but don't get discouraged by how uncertain the process can be.

This is well put and has been my experience. I always figured it was attributable to the ogive profiles differences (secant, tangent, hybrid, etc.). I never considered throat wear but it makes sense. Sometimes, when using the Hornady OAL gauge, the bullet does not come to a "hard stop" against the lands and you kinda feel this mushy "friction zone" of uncertainty that can be .030 to .050" wide. Most of the time, I don't have a problem but every so often, when I switch up bullets it happens. When it does, I usually regroup and look at loading to maximum mag length or published COL data. This happened with my .204 Ruger, only in that case, I was just pushing the little 39 grain Sierra right out of the case before it even encountered the lands!
 

Barrelnut

Well-Known Member
LRH Team Member
Joined
Dec 16, 2013
Messages
4,648
Location
End of the Oregon Trail
There is another difference between the Hornady gauge measurements and the Alex method. The Hornady gauge actually measures from the shoulder of the brass to the lands. The Alex method truly gives you a cartridge base to ogive measurement. There can easily be .005 difference.
Reason is the Hornady Modified Case is made from a piece of unfired brass which is shorter than the chamber. When you insert the brass case with the bullet, the shoulder of the case stops at the shoulder of the chamber. Thus the measurement is only from the shoulder to the ogive. Now when you use the gauge to take a measurement on the caliper, the measurement is from the base of the case's base to the ogive. The main discrepancy in the measurements is because the Modified Case is shorter than your chamber. The Alex method is different. It is truly measuring the length from the bolt face to the ogive. If you have case that has been fired a few times and truly reflects the size of the chamber, you can measure the difference between it and the Modified Case to get a better measurement with the Hornady gauge.
 
D

Deleted member 107796

Guest
I just completed a rough reference length test when loading 7WSM with 150gn Berger Classic Hunters. At max OAL of 2.860", they were toughing the lands as indicated by the old guy's method of black pen. it was easy to dial this to .005" increments to a reference length of 2.840", easily seeing when the bullet got of the lands. I conclude that this method is good to within +/-.005". When I look at the range of off the lands distances, this is not bad.
 

BountyHunter

Well-Known Member
Joined
Jun 13, 2007
Messages
5,506
Location
Wilmington NC
Here is what you need to keep in mind. Finding the lands IS ONLY needed IF you only fire single shot. Otherwise, start at max COAL for the magazine and work back from that. Pretty easy to find a load that works and that is what you are after.

Do not over complicate it with a measurement that you do not need and for all practcial purposes is meaninless for magazine rifles.
 

Oi.223

SCAMMER
Joined
Oct 27, 2018
Messages
113
Location
SCAMMER
Insert a length of dowel, or a cleaning rod with a flat tip or cut-off jag, into the muzzle until it touches the bolt face. Score the cleaning rod with a small mark using a knife laying flat across the muzzle. Next, drop the bullet (not a round) you want to measure into the throat and hold it against the rifling. Then, insert the cleaning rod into the muzzle until it rests against the bullet tip. Again, score the rod at the muzzle.

Using your calipers, measure the distance between the two score marks on the rod. The distance is the maximum overall cartridge length for that particular bullet. Do it a couple times with different bullets out of the same box to verify the marks are accurate.

Subtract .005" from your measure, or whatever you're comfortable with, and you have the COAL you're looking for.

Remember, other bullet types may be quite different because of their ogive shapes.
 

Greyfox

Well-Known Member
Joined
Jan 21, 2008
Messages
5,931
Location
Northeast
With a consistent BTO method established, I will keep a couple of of the bullets to monitor throat erosion once a new barrel is broken in. Having done this for the last eight years or so, has proven to work well. Combined with scoping the bore for fire cracking, and accuracy testing, it has proven to be an excellent means of projecting barrel life...very useful with my high volume and/or high pressure shooters.
 
Top