Once Fired brass....What is happening here?

[ABL_ZA]

I am preparing to reload for the first time. Can you help me diagnose what is going on here?

Disclaimer:

• I am not sure if this is the right forum but we dealing with case measurements so maybe it is
• I am a newbie, please help with my terminology if not correct.
• I have never loaded but I am getting set up and doing the research.

Context:

I have a new rile - Tikka T3x 6.5CM (don't hate, finding left-hand factory rifles in South Africa is almost impossible)

I shot 5 rounds of factory 143gr ELDX and have some interesting results.

Results:

A heavy bolt
Case lengths (1.912 | 1.909 | 1.908 | 1.908 | 1.908)
On the Hornady Headspace comparator kit I get a headspace reading of 1.560 across all 5 cases
Using the Wilson Depth micrometer I get a hair under 0.100 (which is 0) which I believe means we are at max headspace

Diagnosis:

Does this mean my chamber is larger than SAAMI? SAAMI for 6.5CM max is 1.551
OR
If my Wilson Depth micrometer says we at max and SAAMI for 6.5CM max is 1.551 does that mean I need to recalibrate the micrometer?

 

[Cascade Hemi]

It doesn't mean anything. Bump your shoulders .001 to .003 and quit worrying about SAAMI specs.

 

[Choid]

The Wilson gages are awesome, but people here seem to overthink them. They are great because unlike a lot of case gages they don't require body sizing to use, so you can take a before and after measurement, but the only measurement that actually matters is the delta, not the absolute measure. So measure your fired case, then measure your sized case, and look for a decrease of .002 +-

 

[PB&J.]

It doesn't mean anything. Bump your shoulders .001 to .003 and quit worrying about SAAMI specs.

X2. Unless you plan on shooting those handloads out of multiple rifles, then you will need to compare headspaces and work out a happy medium.

Your chamber is your chamber, bump the shoulder .001-.003 and stop stressing. The whole point of handloading is to optimise a load to YOUR rifle.

 

[zeroz]

X3. A gauge is just that, it gives you a reference so you know where you need to go. In this case (pun intended), bump .002 back.

 

[NH4X]

Your question has been answered OP...........next question ?

 

[ABL_ZA]

Thank you all. Ok next question then.....

I am going to take an OAL gauge to measure seating depth.

1. Can I use a new Hornady modified case with a headspace reading of 1.559 (my own fired brass has 1.560)
2. Should I rather make my own modified case with the correct headspace?

Can someone tell me when you make a modified case, why do you not resize (ie. bumping 0.002)?

 

[Gohring65]

No need, your distance to the lands is from your bolt face to the lands. The cartridge case size won’t matter it’s just a gap filler. Don’t over think the lands measurement. It’s a measurement that’s changing often, you need it if you want to monitor throat erosion and to keep your bullet with in its preferred distance from the lands. As long as you are using the same equipment each and every time you measure, your parameters will remain the same.

 

[Haney]

Can someone tell me when you make a modified case, why do you not resize (ie. bumping 0.002)?

It assures you are measuring from the bolt face because it was fired in that chamber . Store bought does not give you that .

 

[ABL_ZA]

No need, your distance to the lands is from your bolt face to the lands. The cartridge case size won’t matter it’s just a gap filler. Don’t over think the lands measurement. It’s a measurement that’s changing often, you need it to monitor throat erosion and to keep your bullet with in its preferred distance from the lands. As long as you are using the same equipment each and every time you measure, your parameters will remain the same.

Thanks for your response. If I can just clarify

If you kept the seating depth the same, would headspace not impact the distance to the lands?

 

[Gohring65]

Thanks for your response. If I can just clarify

If you kept the seating depth the same, would headspace not impact the distance to the lands?

Only slightly with new brass, if you’re bumping shoulders consistently, you do your seating depth test, then measure with the same equipment each time it will be the same.
Everything has to be stable, brass size, good quality bullets, measuring tools etc. or you’re creating tolerance stack and the measurements will be all over the place and worthless.

 

[Haney]

Thanks for your response. If I can just clarify

If you kept the seating depth the same, would headspace not impact the distance to the lands?

Yes, it does impact it . The truer the case is to your chamber the better .

 

[supercorndogs]

Thanks for your response. If I can just clarify

If you kept the seating depth the same, would headspace not impact the distance to the lands?

IT depends on what you mean by headspace. If you mean the headspace you created when sizing the case, no that does not change the distance from the bolt face to the lands. IT only serves to make the brass case to fit in the chamber.

If you mean measuring with a modified case then yes it does effect your measurement vs actual because you push the case into the chamber up to the shoulder junction, with Hornady's case holder/bullet pusher that comes in the kit.

If you mean screwing the barrel out increasing headspace, then yes but not very much. For example if you screwed your barrel out .003 to increase your headspace, then your distance to the lands {I.E. the measurement from the bolt face to the lands} would increase .003.

The cost of a tap to make your own modified gauges is roughly the same as 1 modified case. I have some modified cases and a tap, but I usually use the method where you split a neck on a sized case, put a bullet in the case and chamber it.

 

[Haney]

IT depends on what you mean by headspace. If you mean the headspace you created when sizing the case, no that does not change the distance from the bolt face to the lands. IT only serves to make the brass case to fit in the chamber.

If you mean measuring with a modified case then yes it does effect your measurement vs actual because you push the case into the chamber up to the shoulder junction, with Hornady's case holder/bullet pusher that comes in the kit.

If you mean screwing the barrel out increasing headspace, then yes but not very much. For example if you screwed your barrel out .003 to increase your headspace, then your distance to the lands {I.E. the measurement from the bolt face to the lands} would increase .003.

The cost of a tap to make your own modified gauges is roughly the same as 1 modified case. I have some modified cases and a tap, but I usually use the method where you split a neck on a sized case, put a bullet in the case and chamber it.

With a case that is not fired in said rifle how do you know exactly where it relates to the bolt face ? You are stacking variables from the very first move . I guess the question is how serious does a guy is about knowing exactly where the lands are . We all have different acceptable tolerances . I jam most target bullets , it matters a great deal to me .

 

[supercorndogs]

With a case that is not fired in said rifle how do you know exactly where it relates to the bolt face ? You are stacking variables from the very first move . I guess the question is how serious does a guy is about knowing exactly where the lands are . We all have different acceptable tolerances . I jam most target bullets , it matters a great deal to me .

You could use your headspace comparator to get the difference between a fired case and modified case. Most people aren't jamming bullets and are finding loads shoot more consistently for longer farther off the lands. You a see a lot more people running .05-.07 off, where .03 was a mile 20 years ago, even though a lot of factory rifles were jumping .2 and shooting fine. Instead of wasting time trying to kiss the lands and chase the lands. Most bullets used today are not particularly jump sensitive.

 

[straightshooter1]

No need, your distance to the lands is from your bolt face to the lands. The cartridge case size won’t matter it’s just a gap filler. Don’t over think the lands measurement. It’s a measurement that’s changing often, you need it to monitor throat erosion and to keep your bullet with in its preferred distance from the lands. As long as you are using the same equipment each and every time you measure, your parameters will remain the same.

That's called "chasing the lands", which can be very problematic since doing so one is constantly changing the seating depth effecting the pressure curve as one keeps up with the throat erosion. Since seating depth is so important in finding a good accuracy node, once found, you really don't want change it until there's enough throat erosion that effects that pressure curve. The seating depth is way more important than the bullet jump.

It took me awhile to learn this as I used to listen to such advice. Some time ago I decided to test this issue. I kept my seating depth constant with my .308 for over 2,000 firings where the throat eroded by ~.034. During that time it maintain very good accuracy. Before, when I was chasing the lands, I was constantly having to make powder adjustments, using up precious components, to find what worked with the new seating depths as I maintained a particular jump. NO MORE!

 

[Gohring65]

That's called "chasing the lands", which can be very problematic since doing so one is constantly changing the seating depth effecting the pressure curve as one keeps up with the throat erosion. Since seating depth is so important in finding a good accuracy node, once found, you really don't want change it until there's enough throat erosion that effects that pressure curve. The seating depth is way more important the bullet jump.

It took me awhile to learn this as I used to listen to such advice. Some time ago I decided to test this issue. I kept my seating depth constant with my .308 for over 2,000 firings where the throat eroded by ~.034. During that time it maintain very good accuracy. Before, when I was chasing the lands, I was constantly having to make powder adjustments, using up precious components, to find what worked with the new seating depths as I maintained a particular jump. NO MORE!

I agree, it’s totally overrated and not necessary.

 

[Sniperwannabee]

I have a new rile - Tikka T3x 6.5CM (don't hate, finding left-hand factory rifles in South Africa is almost impossible)

Why would anyone hate? Tikka is world renown for being possibly the best rifle for the money