Question on measuring chamber length

[wburke2010]

So I have my new rifle setting here and I am about to work up some loads but I need to measure what length to load them to. So I get the hornaday chamber tool with the correct case and start to measure.

I tried it six times

Length to Ogive 2.2235 inches OAL 2.8225 Inches
2.2355 2.8390
2.2385 2.8370
2.2400 2.8395
2.2500 2.8500 I don't think I did this one as equally as the others that is why I have six sets of numbers.
2.2360 2.8340

So my question is should I just go with a Ogive length of 2.23 inches? or are there not enough number to get a good statistic?

What would say would be a good number to use as a chamber length.

Thanks, although I have been reloading for awhile this is the first time I have a really nice rifle worth going off the deep end and doing it right.

Walter

 

[wburke2010]

Forgot to add this will be for a 243 win.

Walter

 

[Layton]

When you measure are you pulling the comparetor real tight to the bullet? Reason asking is your measurements vary alot.

L

 

[wburke2010]

Not too tight, I was trying to do it equally and the same each time.

Walter

 

[Layton]

Take your measurements when it just touches and see what you get. No need to apply any pressure.

 

[Sniper Uncle]

Not sure I follow your process. Did you use the Hornady COAL tool and then the comparator to get the ogives for each one? If so, how sure are you that you were consistent in your pushing the bullets against the lands? Your differences between COAL and Ogive OAL seem to be fairly consistent, but your COAL's are quite a lot different. This makes me suggest that you do it over again, and try for more consistency in placing the bullet against the lands but not jammed.

 

[wburke2010]

Yes I am using the hornaday tool then measure the OAL and ogive length with calipers but I took the comparator off, I know that the OAL with vary a little because the bullet but I wanted a close idea of OAL to make sure it would work fine in mags and so forth.

I retried it five more times to make sure that I was not applying to much pressure of the comparator and using the same pressure on the Hornaday tool.

My first reading was 2.2015 which I am not counting because I don't think it was all the way against the lands. so the next five measured

2.25
2.2555
2.2545
2.2550
2.2550

Those are all using the comparator without applying to much pressure.
So I think that answers my question there.

Thanks Layton, I guess I was using too much pressure and it varied to much.

Walter

 

[Sniper Uncle]

Yes I am using the hornaday tool then measure the OAL and ogive length with calipers but I took the comparator off, I know that the OAL with vary a little because the bullet but I wanted a close idea of OAL to make sure it would work fine in mags and so forth.

I retried it five more times to make sure that I was not applying to much pressure of the comparator and using the same pressure on the Hornaday tool.

My first reading was 2.2015 which I am not counting because I don't think it was all the way against the lands. so the next five measured

2.25
2.2555
2.2545
2.2550
2.2550

Those are all using the comparator without applying to much pressure.
So I think that answers my question there.

Thanks Layton, I guess I was using too much pressure and it varied to much.

Walter

So this is just ogive measurement now. Okay. They do look a whole lot more consistent. I would recommend backing off of this by what you consider to be the desired jump to the lands and then develop the load from there. Just be sure that you don't have a "long one" slip by and jam in the lands with a high charge behind it.

 

[wburke2010]

So this is just ogive measurement now. Okay. They do look a whole lot more consistent. I would recommend backing off of this by what you consider to be the desired jump to the lands and then develop the load from there. Just be sure that you don't have a "long one" slip by and jam in the lands with a high charge behind it.

Yeah this is just the ogive length. That was the first time using the tool so I guess I just needed a little practice to get the feel. The OAL were just there so I could make sure it would fit the mag and just for some records.

Walter

 

[Bob 964]

I had the same problem the first time I tried using my Hornady Lock-N-Load OAL Gauge and modified .308 case and comparator. It was hard for me because I was trying to feel for something I had never felt before, so I had no idea if I was doing it right. I got a wide range of measurements too. So... I took a fired decapped case and cut a slot through the neck with a Dremel tool and put a bullet in the neck so that I had a very long COAL. When I closed the bolt, once the bullet contacted the lands it pushed back into the case neck until the bolt was fully closed. Then I carefully removed the round and measured the OAL using the comparator and caliper. This gave me an idea of where my measurements ought to be. I measured and remeasured using the OAL Gauge until I got consistent measurements that were close to the one I got using the slotted case neck. At least then I knew what it should feel like.

 

[fx77]

Simpler way to do this is to make a long dummy round (no primer or powder) for the bullet U wish to use
close the bolt on the round
Extract the round and then measure with the comparator and your gage..The bullet is in the lands , often called the jam, when the land marks on the bullet are equally long as wide.

 

[Layton]

I guess I was using too much pressure and it varied to much.

Walter

NP, I'm betting just about everyone who has ever used that tool does the same thing first time around. I did.

 

[vh20]

A quick suggestion with the OAL gauge is to use a long wooden dowel in the bore against the bullet tip. With a little manipulation, you can keep the bore guide for the gauge jammed up into the chamber, and use the fingers of one hand to manipulate the pushrod against the base of the bullet, while using the fingers of the other hand to manipulate the dowel and push against the tip of the bullet. A little back and forth between the pushrod and dowel and you can feel exactly when the bullet just touches the lands, when it "sticks", and when it un-sticks. Once you have the feel for it, you can then lock down the set screw on the pushrod with confidence. My measurements were very repeatable.

 

[Sniper Uncle]

A quick suggestion with the OAL gauge is to use a long wooden dowel in the bore against the bullet tip. With a little manipulation, you can keep the bore guide for the gauge jammed up into the chamber, and use the fingers of one hand to manipulate the pushrod against the base of the bullet, while using the fingers of the other hand to manipulate the dowel and push against the tip of the bullet. A little back and forth between the pushrod and dowel and you can feel exactly when the bullet just touches the lands, when it "sticks", and when it un-sticks. Once you have the feel for it, you can then lock down the set screw on the pushrod with confidence. My measurements were very repeatable.

Hey, thanks for the tip. Sounds like a great way to do it.

 

[FLIGHT762]

A quick suggestion with the OAL gauge is to use a long wooden dowel in the bore against the bullet tip. With a little manipulation, you can keep the bore guide for the gauge jammed up into the chamber, and use the fingers of one hand to manipulate the pushrod against the base of the bullet, while using the fingers of the other hand to manipulate the dowel and push against the tip of the bullet. A little back and forth between the pushrod and dowel and you can feel exactly when the bullet just touches the lands, when it "sticks", and when it un-sticks. Once you have the feel for it, you can then lock down the set screw on the pushrod with confidence. My measurements were very repeatable.

This is the way I use the Hornady tool, but I use a cleaning rod with no tip attached to feel the bullets lightly into the lands. It gives good, repeatable readings. You do have to practice a bit to get the feel.

 

[wburke2010]

Well I got a chance to shoot the loads I worked up and the results were great.

http://www.snipershide.com/shooting...es/185044-my-dream-rifle-finally-reality.html Scroll down to the bottom and there is a range report.

Thanks again for the help

Walter