Am I off my rocker? COAL and OGIVE

[pdog06]

Thanks all. The one thing I noticed. The Norma has probably .065 jump from the lands. The loads I developed were very accurate.

It’s a hunting rifle and not a bench gun, correct? If so sounds like you may be done finding a good load for that bullet? Almost every box of factory ammo has that much jump in most rifles for liability and mag usage reasons, so don’t be too alarmed by that number.
Your buddy recommending .020 of the lands is understandable. That is a very good starting point in the reloading process for rifles where youre not worried about using a magazine. I start there as well, and have also ended there many times cause it shot so good. Or good enough depending on my intended usage.

First you need to decide if using the magazine is a priority. If so then you now already know your max COL, regardless of bullet choice.

If so then set it at slightly below mag length(check every few due to OAL differences of bullets) and worry more about powder charge to verify accuracy. If still not good enough you may need a powder change, or even try another bullet.

As always start low and work up to max. What is max in one rifle or in the book may not be max in your rifle! And often different loading data books have different max loads! Do some comparisons with different load data for your intended bullet(like with the bullet companies data and the powder companies data).

 

[USAFRet]

What is the case head to shoulder measurement on the Hornady tool case and what is the same measurement on a fired case with primer rem

What is the case head to shoulder measurement on the Hornady tool case and what is the same measurement on a fired case with primer removed?

Looks like fired case from case head to start of shoulder is 1.507 on the fired case, no primer. It is 1.514 on the Hornady tool case.

 

[USAFRet]

It’s a hunting rifle and not a bench gun, correct? If so sounds like you may be done finding a good load for that bullet? Almost every box of factory ammo has that much jump in most rifles for liability and mag usage reasons, so don’t be too alarmed by that number.
Your buddy recommending .020 of the lands is understandable. That is a very good starting point in the reloading process for rifles where youre not worried about using a magazine. I start there as well, and have also ended there many times cause it shot so good. Or good enough depending on my intended usage.

First you need to decide if using the magazine is a priority. If so then you now already know your max COL, regardless of bullet choice.

If so then set it at slightly below mag length(check every few due to OAL differences of bullets) and worry more about powder charge to verify accuracy. If still not good enough you may need a powder change, or even try another bullet.

As always start low and work up to max. What is max in one rifle or in the book may not be max in your rifle! And often different loading data books have different max loads! Do some comparisons with different load data for your intended bullet(like with the bullet companies data and the powder companies data).

Excellent advice. Thank you!

 

[USAFRet]

OP, light reading material. https://bergerbullets.com/shoot-better/shooting-knowledge/measuring-coal-and-cbto/#:~:text=A very common practice in,optimal seating depth for precision.

Funny, my buddy suggested the same. Reading today, unless I can get a hall pass to go shoot. Haha.

 

[USAFRet]

I don’t believe that you stated what powder charge you were at when you seen pressure signs but I would keep your seating depth and drop a half grain to start, then test in
.3 less increments.

It was 42.9. So, early on, I made the mistake of matching another powder grain for grain (Norma does not list their load data with standard powders, it's all Norma powder). I did work up from 41 in .3 grain increments, but did not remember having bolt resistance, but back then I did not know what I do now. I got very good groups and that load has been sitting since I first started.

Fast forward to me checking my scope for deer season. Shot same outstanding groups, but significant bolt resistance. Came home and did research from what I have learned since I started and I was up to 1 - 2 grains over maximum for that powder and bullet weight.

 

[Schippergreg]

It was 42.9. So, early on, I made the mistake of matching another powder grain for grain (Norma does not list their load data with standard powders, it's all Norma powder). I did work up from 41 in .3 grain increments, but did not remember having bolt resistance, but back then I did not know what I do now. I got very good groups and that load has been sitting since I first started.

Fast forward to me checking my scope for deer season. Shot same outstanding groups, but significant bolt resistance. Came home and did research from what I have learned since I started and I was up to 1 - 2 grains over maximum for that powder and bullet weight.

In my experience seating depth is more important than powder charge. If your seating depth is off no powder charges will shoot well. If the seating depth is correct there should be multiple powder charges that shoot well. It appears that your seating depth is good so I’d retest your powder charges starting with a lower weight and work up to the book max.

 

[USAFRet]

Well, did a little ladder test today suggested by a buddy. Ran the Accubonds .020 off lands, which is about .035 shorter than the book. Got decent results with a couple of nodes having very stable velocities and the groups were within about .3". So, I am going to load some of those for group testing this week. Seems like basing my seating on the rifle vs the book may have done some good. We shall see.

Between jobs right now, so this seems to be my job. I cannot see how retired people can't find things to do.

 

[WEL]

Don’t be afraid to jump those accubonds. I have seen group size reduce a good bit by experimenting with it. I usually go 20,40,60,80,100 off. Going from.020 to .080 cut group size almost in half on a 7mag with the 160.

 

[6MMsteve]

Thank you, Bill.

Does everyone else waste tons of powder, bullets and primer to get to a point that a light bulb comes on?

No just buy better barrels

 

[dellet]

Post #42 is a huge bit of data.

With the numbers above the bullet in your case will be at least .007” closer to the lands at the base to ogive length as your Hornady tool. So if the Hornady tool is a touch. Your cartridge will be an about .010” jam.

Touch is determined by the distance between the point in the chamber where the shoulder should touch, and the lands. An extreme example would be two cartridges with the same base to ogive. One has zero head space and the bullet touching the lands. The other has 1/2” headspace and the bullet touching the lands.

Where this comes into play is the load you like, might not be as bad as you thought. It could be just a slight jam. If you can resize the brass longer, setting the shoulder back less, it might pull the bullet out of the lands. This may or May not be an issue, but it is a good example of why using ALL the measurements available is important.

As long as your base to shoulder measurements are different than the Hornady tool, the bullet will never be located in the chamber where you think it is.

You can make a modified case out of one of your fired cases. Or I think there is still someone offering this service in the Classifieds. This will help a lot.

 

[USAFRet]

Post #42 is a huge bit of data.

With the numbers above the bullet in your case will be at least .007” closer to the lands at the base to ogive length as your Hornady tool. So if the Hornady tool is a touch. Your cartridge will be an about .010” jam.

Touch is determined by the distance between the point in the chamber where the shoulder should touch, and the lands. An extreme example would be two cartridges with the same base to ogive. One has zero head space and the bullet touching the lands. The other has 1/2” headspace and the bullet touching the lands.

Where this comes into play is the load you like, might not be as bad as you thought. It could be just a slight jam. If you can resize the brass longer, setting the shoulder back less, it might pull the bullet out of the lands. This may or May not be an issue, but it is a good example of why using ALL the measurements available is important.

As long as your base to shoulder measurements are different than the Hornady tool, the bullet will never be located in the chamber where you think it is.

You can make a modified case out of one of your fired cases. Or I think there is still someone offering this service in the Classifieds. This will help a lot.

I measured the cases and they are within about .007 of each other. I was thinking about sending the fired cases into Hornady and have them frill and tap them for the tool.

 

[Texas Solo]

Sounds like your over thinking a bit.
Get the Hornady gauge & modified case. Measure to just touching the lands. Minus .020" and load 5. Go to -030" and load 5 more.FYI...tangent ogives like this. Secant ogives won't.
Secants want .005" off lands or sometimes less. Tangents are way easier to tune, generally with wide nodes for seating depth.
OAL? What's that? Who cares. It's the best amount of jump for your rifle that your chasing. Find it and the OAL is what it is, period. Mag requirements can screw this up though.

All this seating depth talk is moot until you have a powder charge. Choose your bullet, set it to -020". Then work your powder charge. Once you have that, play with depth.

Welcome to the rabbit hole.

 

[USAFRet]

Don’t be afraid to jump those accubonds. I have seen group size reduce a good bit by experimenting with it. I usually go 20,40,60,80,100 off. Going from.020 to .080 cut group size almost in half on a 7mag with the 160.

Much appreciated. I have only played with seating depth a little. My problem has been being all over the map trying to reload for 3-4 rifles at a time. I am stopping and working solely on this rifle before moving on, as this will be my hunting rifle for this season.

 

[SKWERLZ]

Manufacturers recommendations is simply that. It was the tested measurement for that load in that rifle. Your rifle will have a different set of numbers entirely. No two bullets will have the same measurements since the ogive is positioned in different areas on the bullet profile. .002 to .003 per increment is good for checking seating depth accuracy.

^^^^^^^

 

[USAFRet]

Sounds like your over thinking a bit.
Get the Hornady gauge & modified case. Measure to just touching the lands. Minus .020" and load 5. Go to -030" and load 5 more.FYI...tangent ogives like this. Secant ogives won't.
Secants want .005" off lands or sometimes less. Tangents are way easier to tune, generally with wide nodes for seating depth.
OAL? What's that? Who cares. It's the best amount of jump for your rifle that your chasing. Find it and the OAL is what it is, period. Mag requirements can screw this up though.

All this seating depth talk is moot until you have a powder charge. Choose your bullet, set it to -020". Then work your powder charge. Once you have that, play with depth.

Welcome to the rabbit hole.

I have learned the OAL ain't much, so I am using the Hornday gauge to measure Ogive instead.

I did some ladder tests yesterday and have a few nodes that were promising. I am going to work on those for grouping, ES and SD. Once I get one or two that seem pretty stable, I am going to start playing with seating depth changes by about .003 at a time.