OAL length guage errors

[Erik Cortina]

Ill try this later tonight. So would this be the true measurement to the lands? And will i have to adjust powder charge again?

This is what I would call "jam"

It is simply a reference point. Figure out the difference between jam and what you are loading now and you will know how far you need to be away from "jam" to be where you are now.

 

[Joe R]

Quote

jaybraysaid: I thought I would post this though embarrassing, as maybe it would help other reloader's like myself with far less experience than most people that frequent this awesome site. I came across a post entitled 6 dasher .020 jump on this site and read a reply from the forumboss on page two regarding the proper way to use the hornady oal guage to find the lands. I have been doing it wrong. When I use it to find the lands I very gently pushed the rod forward until the bullet made the slightest contact with the rifling, like JUST touching and called it good and made my measurement.



That's the way I've been doing it. I've been sitting here dumb and happy letting real accuracy slip through my fingers.

Well, I just re-measured my distance to the lands (3x) according to the instructions above and sure enough it increased by .015.

Thanks jaybray, many blessing to you and your loved ones for illuminating me. I can't wait to get out to the range and see how that affects things.

kindest regards,

Joe

 

[jaybray]

Hey Eric, I did what you said with a clean chamber and made sure the hornady case didn't back it self out when I pushed real hard on the stick and I got 1.843 4 times and 1.842 twice. That bullet went along ways in. So my original measurement was 1.673. Next with the 3 taps was 1.700 and now with lots of force im at 1.843. The shank of the bullet is well over half way up the case!! So is this method to find the lands where you yourself would start when working up a load for a new rifle?

 

[jaybray]

Ill try this later tonight. So would this be the true measurement to the lands? And will i have to adjust powder charge again?

This is what I would call "jam"

It is simply a reference point. Figure out the difference between jam and what you are loading now and you will know how far you need to be away from "jam" to be where you are now.

Now I know what you mean. I never realized what the term jammed really meant. I thought my first loads were jammed 10 ITL. I guess they sorta kinda were.

 

[Erik Cortina]

Hey Eric, I did what you said with a clean chamber and made sure the hornady case didn't back it self out when I pushed real hard on the stick and I got 1.843 4 times and 1.842 twice. That bullet went along ways in. So my original measurement was 1.673. Next with the 3 taps was 1.700 and now with lots of force im at 1.843. The shank of the bullet is well over half way up the case!! So is this method to find the lands where you yourself would start when working up a load for a new rifle?

So now you know why I tell people to do it that way... Because it's easy to get repeatable results!

I start working up loads .020" away from jam.

 

['Freak]

Hey Eric, I did what you said with a clean chamber and made sure the hornady case didn't back it self out when I pushed real hard on the stick and I got 1.843 4 times and 1.842 twice. That bullet went along ways in. So my original measurement was 1.673. Next with the 3 taps was 1.700 and now with lots of force im at 1.843. The shank of the bullet is well over half way up the case!! So is this method to find the lands where you yourself would start when working up a load for a new rifle?

So now you know why I tell people to do it that way... Because it's easy to get repeatable results!

I start working up loads .020" away from jam.

So, .020” away from jam, a for real “jam” as described above, could easily be well beyond the point of initial contact, right?

What if dealing with a projectile/chamber combination where starting work up seated .020” away from jam or contact of any kind just is not possible, would you start out as near as can be keeping a bullet diameter’s length in the neck and then back away in .003” increments increasing the jump even further?

 

[Barlow]

I use the Eric described process. It gives a good baseline to start with. Barlow

 

[rjnallie]

I set mine now the way Eric described, as it seems the most repeatable. When I used the Hornady and then the Sinclair gauge, it is wholly based on how much pressure you put on the rod. When I did use the rod type gauge, I put a collar about 1/2" from the end of the rod with a spring extending past the rod 1/2". You can push the spring in until your finger touches the rod end, this gave very consistent readings. It's just a reference point, but it is confusing when some tells you to start .020 off the lands.
Raymond

 

[amlevin]

The key to accurate measurements in any "discipline" is to make sure that every variable is controlled.

When using the Hornady gauge the two largest variables that can cause a wide range of measurements in COAL are how clean the chamber/throat area are and how much force is used to seat the bullet in the lands.

Clean is easy to take care of . Force is a little more challenging. Tapping or pushing with a thumb, etc, and vary in results.

Here's a nice tool that can eliminate the force variable. It's used by building inspectors to make sure that ADA compliant doors don't take too much force to open.

It's called an ADA Door Pressure Gauge. They can be purchased for varying prices up to around $50 but all they are is a tube, spring, and rod with a simple "tell-tale" like an O-ring on it that shows how far the rod compressed the internal spring.

Anyone could make one out of a piece of brake line (steel tubing), a piece of round stock, a spring, and an O-ring. Put a line around the rod to show how much pressure you want on the rod when pushing the end of the tool to seat the bullet.

Even simplify the took by finding a piece of tubing that just fits over the end of the tool's rod, cap it, put a spring in it, then press forward. Mark the Hornady tool's rod when you have the desired "push" on it and that will allow you to repeat that pressure every time you measure.

You also won't have to send your thumb out to be calibrated 8)

 

[Joe R]

OK Eric,
This morning I measured the bullet jam your way also. Below is the info that falls out. Interestingly the tap method winds up being pretty close to the jam method minus the 0.02. So given these dimensions on this bullet I should be loading to length of 3.242 right?

Joe

 

[snakepit]

I am just curious but does it really matter which one of these three methods you use (touch, tap or jam) and the readings you get if you just use them as your starting point in the bullet seating portion of your load developing.

 

[Erik Cortina]

OleFreak, I don't subscribe to the idea of keeping a bullet diameter in the neck. Push bullet out as far as possible but still allows good grip on bullet and concentric ammo and then seat into case .003" at the time when testing seating depth.

 

[Erik Cortina]

I am just curious but does it really matter which one of these three methods you use (touch, tap or jam) and the readings you get if you just use them as your starting point in the bullet seating portion of your load developing.

They do not matter as long as you can get accurate and repeatable results. For me, the jam method has been the most repeatable.

 

[Erik Cortina]

OK Eric,
This morning I measured the bullet jam your way also. Below is the info that falls out. Interestingly the tap method winds up being pretty close to the jam method minus the 0.02. So given these dimensions on this bullet I should be loading to length of 3.242 right?

Joe

3.242" is correct, however, that's where I start developing loads. Adjust from there. I never load past jam, as that's where risk of sticking bullets happens.

 

[Joe R]

Quote from: Joe R on Today at 08:41 AM

OK Eric,
This morning I measured the bullet jam your way also. Below is the info that falls out. Interestingly the tap method winds up being pretty close to the jam method minus the 0.02. So given these dimensions on this bullet I should be loading to length of 3.242 right?

Joe




3.242" is correct, however, that's where I start developing loads. Adjust from there. I never load past jam, as that's where risk of sticking bullets happens.

Erik, thanks for the response. Does that mean you move towards the jam or away from the jam?

Joe

 

[jaybray]

And here I was worried that I might start pulling bullets out of the case when ejecting an un fired case and spilling powder all over my nice bat action when I was jammed 10 ITL at my original measurement of 1.683. :. I tried this with a 95 berger jammed hard and there is hardly any bullet shank in the case!!. This barrel does have around 1700 rounds through it and there must be some throat erosion . So for now I might as well just keep using 1.710 as jammed in the lands because it shoots very well for what I do which is shooting at 200 yards at my local range for fun against 300 and 7mm mags and various other grizzly bear and coyote hunting caliber guns shooting mostly factory ammo. Totally unfair against a 6br with a bat action, Krieger barrel and 36x sightron scope but so much fun cause I win every time!! Next barrel I will use Eric's method and go from there. Now I know what hard jam really means. Thanks Eric.

 

[Erik Cortina]

Quote from: Joe R on Today at 08:41 AM

OK Eric,
This morning I measured the bullet jam your way also. Below is the info that falls out. Interestingly the tap method winds up being pretty close to the jam method minus the 0.02. So given these dimensions on this bullet I should be loading to length of 3.242 right?

Joe




3.242" is correct, however, that's where I start developing loads. Adjust from there. I never load past jam, as that's where risk of sticking bullets happens.

Erik, thanks for the response. Does that mean you move towards the jam or away from the jam?

Joe

Away from jam. You may have seen my posts where I reference it as Jam -.020"

 

[Joe R]

Erik, thanks again, your counsel is greatly appreciated.

Joe

 

[DennisH]

Using the "jam" method, are you seeing any signs of the land markings on the bullet?

Using a magnifying glass, I do see them. Just wondering about everyone else. I guess it really matters how much "pressure" your putting on the rod.

I have a certain way I hold the body with one hand, then I gently push the bullet forward with the other. At this point I tap the rod 3 times and hold fairly tight when tightening the lock screw.

Almost all of the time with Berger's, I usually average .001 or less on all of my rifles. Other bullets may vary a little more. These bullets end up in the sighter cup.

 

[Erik Cortina]

Using the "jam" method, are you seeing any signs of the land markings on the bullet?

Using a magnifying glass, I do see them. Just wondering about everyone else. I guess it really matters how much "pressure" your putting on the rod.

I have a certain way I hold the body with one hand, then I gently push the bullet forward with the other. At this point I tap the rod 3 times and hold fairly tight when tightening the lock screw.

Yes, you should see land marks on the bullet. At jam point, rod pressure matters less because you would have to deform bullet to push it in further.