Help with measuring Chamber length.

[archp625]

I bought the Hornady gauge and I’m trying to measure my chamber length. I am getting numbers all over the place. I am using their brass and a 147 gr ELD-M.

Should I just load to factory COAL and be done or what should I try. I just started reloading.

 

[Tod osier]

I am no expert, but I can measure very consistently with mine. Is the bullet freely moving in the neck of the case? Have you tried using a cleaning rod opposite the gauge to get a feel for the bullet engaging the rifling? Have you watched a video or two of people doing it?

I pin the gauge in pretty firmly and keep the case seated while I manipulate the bullet. I'm using a fired case of my own that I tapped, but I don't see that being a major issue with consistency.

 

[archp625]

I will try again today. It was very late last night.

 

[Tod osier]

I found that using the cleaning rod opposite the gauge pusher helped get the feel down. Rod in one had pusher in the other, repeatedly seating against the rifling and out. Check your bullet to see you aren't maring it or that it doesn't have some kind of mark right at the ogive.

 

[Wrench]

When you say all over the place, are you talking like .010" ?

It takes a while to develop the feel. You're kissing a very lightly ramped surface into an very lightly ramped surface.....do it 20 times and record your numbers.

 

[rayporter]

the measurement will be a starting place for loads. every one that does it this way will get a different reading and it does not matter if the readings are a couple thousands different. it is a starting place and you wont likely load at that measurement.

 

[archp625]

When you say all over the place, are you talking like .010" ?

It takes a while to develop the feel. You're kissing a very lightly ramped surface into an very lightly ramped surface.....do it 20 times and record your numbers.

0.100” off.

 

[Wrench]

0.100” off.

Whoa.

Try turning the bullet around and see if you can hit a repeatable number.

 

[Unknown Munitions]

0.100” off.

That's way too much variance, I often find some junk in the chamber or lands when readings are this far off. If you consistently engage the rifling all the way around the bullet it will often get stuck when you pull the case out. I use a cleaning rod on the opposite side to push the bullet back out. Your final results should all be within +/- .002" of each other across at least 5 readings. If you're local to Post Falls you can stop by the shop for some assistance.

 

[archp625]

That's way too much variance, I often find some junk in the chamber or lands when readings are this far off. If you consistently engage the rifling all the way around the bullet it will often get stuck when you pull the case out. I use a cleaning rod on the opposite side to push the bullet back out. Your final results should all be within +/- .002" of each other across at least 5 readings. If you're local to Post Falls you can stop by the shop for some assistance.

Thanks for the invite. I’m located in the armpit of America. I’m in Missouri.

 

[HiMtnHntr]

Watch a youtube video on it by a guy called hornady loader. You shouldn't get numbers too far apart.

 

[archp625]

I just ran down and did it 12 times. Here are my numbers.
2.301
2.3345
2.310
2.2645
2.2725
2.2725
2.2720
2.312
2.3075
2.2755
2.3110
2.2935

Avg 2.299 CBTO
COAL is 2.952 which is 0.003” off SAAMI specs. Seems so dang odd to me.

 

[HiMtnHntr]

Are you measuring to bullet ogive or overall length?

 

[archp625]

Bullet ogive, using comparator.

 

[HiMtnHntr]

I'd be suspecting my caliper at that point.

 

[Unknown Munitions]

I'd be suspecting my caliper at that point.

Agree with you, take some baseline measurements extending your caliper to max open after taking reading, then closed, then measure again to check for variance.


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[archp625]

Guys. I got the issue solved. It was all on me not pressing the gauge equally each time. In another forum a guy I trust so much said to press it as hard as I could without breaking the plastic. He said it’s not the most optimal but will be way more consistent and give me a starting point.

2.342
2.348
2.437
2.344
2.346

Avg 2.345 CBTO with a COAL of 2.994.

I’m going to start loading at 2.325 CBTO.

Thanks again for everyone’s help. I’m sure this won’t be the last question I have being a first time reloader.