Am I off my rocker? COAL and OGIVE

[USAFRet]

Okay, so I am about a year into reloading. Gotten a few loads worked up and I feel like I am throwing darts and a few stick. Basically, loading up .5 grain diff. shooting groups and staying within factory recommended COAL, but have played with seating depth a little.

Working a 6.5 CM. It is a CVA Cascade and it is really an accurate rifle. Lucked into a super accurate load, but it was one of my first ones and realized my calculations were off and I was overpressured, as I was setting the scope for deer season and I was getting bolt resistance. Came back and checked my numbers and the way I calculated, well, it was a novice way of doing things when you don't have the powder listed. lesson learned.

So, a buddy sent me a video and been doing some measurements to get .020 off lands as a starting point. What i found freaked me out a little. Two bullets - 140 Nosler Accubond (COAL 2.805) and Norma Bondstrike (COAL 2.803). Here is what I found...

Nosler measurement for OAL into lands is 2.790.
Norma measurement for OAL into lands is 2.880.
Nosler measurement to Ogive into lands is 2.272.
Norma measurement to Ogive into lands is 2.260.
Nosler bullet length 1.358.
Norma bullet length 1.408.

So, given this information, the Ogive is only about .012 difference in the two. However, with them using nearly the same COAL for bullets that have quite different length measurement, one is being jammed into the lands (Nosler) while the other has about .075 jump from the lands (Norma).

So, would it be prudent to measure .20 off lands using Ogive (.020 off lands was the recommendation from the video, and making .003 incremental changes to tighten groups), which is going to give me way different COAL than the manufacturers recommendation?

Am I off my rocker?

 

[Bill Norris]

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]

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.

Thanks! So, the scary part is that .020 off lands for the Norma has me at 2.860 OAL vs 2.803 as recommended. That is huge.

 

[Bill Norris]

Recommended is the key word. Those numbers are really suggestive and only applied to that load in that rifle at testing. Chamber lengths, free bore, reamer designs all play into the numbers. Measuring from base to ogive is a much better and accurate measurement.

 

[Doom]

First off, you are looking at hunting bullets not match grade bullets and you need accuracy, not precision, and reliability. Depending on your rifle's chamber you may not even be able to seat a bullet 20/1000 off the lands. You may also be limited by the magazine length. I would recommend you stay with the ~2.800" recommendation.

As for your measurements I'm suspicious of your measurements on the Nosler. I wouldn't expect that bullet to be near the lands. You should be very careful comparing ogive and overall length between different bullets and the ogive shape can be vastly different between two different bullets of the same weight.

 

[USAFRet]

Recommended is the key word. Those numbers are really suggestive and only applied to that load in that rifle at testing. Chamber lengths, free bore, reamer designs all play into the numbers. Measuring from base to ogive is a much better and accurate measurement.

Thank you, Bill.

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

 

[Sandstorm]

Your staring out without a mentor...and it is what it is till you learn. Just be careful and follow recomendations
with your charges...Use common sense and caution....
This place will help you get better Sir.

 

[Bill Norris]

Thank you, Bill.

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

Well, I suppose some do but the answers to most questions are here. Most of the guys here will say the only stupid question is the one that did not get asked. In regards to your example you have to remember that the ogive of the bullet is the first portion of the bullet to touch the barrel and not the point of the bullet. Therefore, the COAL becomes of lesser importance in finding the most accurate seating depth. When using the base to ogive method you will notice the difference between the measurement of two given bullets will not be near as great as COAL.

 

[USAFRet]

First off, you are looking at hunting bullets not match grade bullets and you need accuracy, not precision, and reliability. Depending on your rifle's chamber you may not even be able to seat a bullet 20/1000 off the lands. You may also be limited by the magazine length. I would recommend you stay with the ~2.800" recommendation.

As for your measurements I'm suspicious of your measurements on the Nosler. I wouldn't expect that bullet to be near the lands. You should be very careful comparing ogive and overall length between different bullets and the ogive shape can be vastly different between two different bullets of the same weight.

I measured it three times. It is correct.

Understood on mag length and such. And, yes, I am not a precision shooter, but I want accurate loads with decent velocity. It has been pretty hit or miss.

The recommendation for starting at .020 off the lands, was actually from a guy building hunting rifles. I want to understand what my rifle likes. For instance, the Norma's had excellent accuracy and they have a massive amount of jump. So, it may be that my rifle likes that.

 

[USAFRet]

Your staring out without a mentor...and it is what it is till you learn. Just be careful and follow recomendations
with your charges...Use common sense and caution....
This place will help you get better Sir.

Oh, I have several mentors. It was one that sent me the load work up video as I sent him some load data that I was frustrated with.

I stay safe, but stupid creeps in now and again.

 

[TTE]

The recommendation for starting at .020 off the lands, was actually from a guy building hunting rifles.

Did he build your rifle ?
If not, your rifle may be set up differently than the rifles he builds.

Reloading manuals are a sliding scale of '1 size fits all' type of advise.

No two rifles are the same, even if chambered consecutively with the same tools by the same smith .... there can be a .0001 + or - difference somewhere ... and some smiths are better than others.

Do the measurements on your rifle for a particular bullet and follow the advise given here. Use what you know and compare it to what you read here.
#1 thing ... be careful as you go.

 

[Ned Ludd]

The fact that nose length can differ widely between bullets, or even within the same Lot# of bullets is only obvious after one realizes it. I mean, if nose length was all over the map, and it is, you have to ask yourself why a company would ever choose to use COAL/COL as a measurement for anything. Maybe the issue is with the people at the companies that choose to use a measurement such as COL for the reloading data they publish. My point is, don't be too hard on yourself for not knowing every detail in the reloading process before you even really get started. You will learn many things along the way, and there will likely be many "light bulb" moments during the journey.

With respect to your issue, there are [at least] a couple common approaches. For your application you could certainly stick with using reloading manual COL values. The advantage with this approach is that you know loaded rounds will always feed from a mag. The disadvantage(s) are typically that you may be giving up excessive usable case volume unnecessarily.

Alternatively, you could try a "finding the lands/.020" off of touching" approach as was recommended to you. However, the results may depend on the rifle's chamber. In fact, some rifles may have chambers throated so long that certain [shorter] bullets may never even touch the lands before the bearing surface is seated out of the case neck (extreme example). Also, it may be that certain bullets seated at .020" off the lands will no longer feed from a magazine.

In any event, there are generally caveats to any approach you might use. Thus, having more than one approach in your "toolkit" for any particular step in the reloading process can sometimes be a good thing, especially when you know how the different approaches relate to one another. This is a perfect example of that. Now you are beginning to have a feel for the difference between CBTO and COL measurements, and what those measurements mean in terms of loaded rounds from a practical viewpoint. That is an important step in the reloading process.

I tend to be a measurement person. I usually take and record every single [accurate] measurement I can. I will re-iterate the "record" part of that statement. A measurement will eventually be useless if you don't actually record it in your reloading data book/manual. If you don't already have one I can't emphasize stongly enough that you should get one and record every measurement you take. The point here is that you can determine the distance to touching using something like a Hornady OAL gauge and still load rounds to a pre-determined COL such as 2.800". Taking the one measurement does not preclude using the other approach. Rather, taking such chamber measurements may help with the decision-making process even if you ultimately end up using a preset COL approach for loaded rounds. Further, once you measure it and record the measurement, you have it if you ever need it.

You're learning more about the process the farther you get into it. That is how it's supposed to work. Keep going!

 

[Webster]

Okay, so I am about a year into reloading. Gotten a few loads worked up and I feel like I am throwing darts and a few stick. Basically, loading up .5 grain diff. shooting groups and staying within factory recommended COAL, but have played with seating depth a little.

Working a 6.5 CM. It is a CVA Cascade and it is really an accurate rifle. Lucked into a super accurate load, but it was one of my first ones and realized my calculations were off and I was overpressured, as I was setting the scope for deer season and I was getting bolt resistance. Came back and checked my numbers and the way I calculated, well, it was a novice way of doing things when you don't have the powder listed. lesson learned.

So, a buddy sent me a video and been doing some measurements to get .020 off lands as a starting point. What i found freaked me out a little. Two bullets - 140 Nosler Accubond (COAL 2.805) and Norma Bondstrike (COAL 2.803). Here is what I found...

Nosler measurement for OAL into lands is 2.790.
Norma measurement for OAL into lands is 2.880.
Nosler measurement to Ogive into lands is 2.272.
Norma measurement to Ogive into lands is 2.260.
Nosler bullet length 1.358.
Norma bullet length 1.408.

So, given this information, the Ogive is only about .012 difference in the two. However, with them using nearly the same COAL for bullets that have quite different length measurement, one is being jammed into the lands (Nosler) while the other has about .075 jump from the lands (Norma).

So, would it be prudent to measure .20 off lands using Ogive (.020 off lands was the recommendation from the video, and making .003 incremental changes to tighten groups), which is going to give me way different COAL than the manufacturers recommendation?

Am I off my rocker?

I think the recommended COAL is just a number so the case will fit in a magazine and the bullet won't get stuck in the rifling if you have to extract a loaded round. I always determined the touch to the rifling for each bullet I use and load 0.010" off the rifling for almost all loads. Works fine in my accurate GH hunting rifles. Depending on your method of determining touch you will probably get a different number. The more neck tension the farther into the rifling the bullet gets pushed. in. I don't consider the touch number I arrive at as an absolute number but a starting reference point. I never jam since I want to be able to extract a loaded round without dumping powder into the action. This is especially bad is you are out in the field hunting and no way to clean the action.

 

[USAFRet]

Thanks all. The one thing I noticed. The Norma has probably .065 jump from the lands. The loads I developed were very accurate. I am thinking my rifle may like a good amount of jump. Going to take it easy. Load the Accubonds with .020 jump and do a ladder test a few grains below max.

 

[6Creed73]

Thanks all. The one thing I noticed. The Norma has probably .065 jump from the lands. The loads I developed were very accurate. I am thinking my rifle may like a good amount of jump. Going to take it easy. Load the Accubonds with .020 jump and do a ladder test a few grains below max.

Sometimes it's the bullet that likes the jump. I typically start .010 off to begin my load development and a lot of bullets like that jump. But I had to push the Hornady A-Tips back to .075, which is a huge amount of jump for me. So it's not just what your rifle likes, but also what the bullet likes.

And I would not worry too much about seating depth at first. Pick a starting point to load up for your powder ladder, get your desired velocity, then you can do a seating depth ladder to tighten the groups.

How are you measuring? The Hornady OAL gauge with a modified case or similar tool is the easiest and most repeatable in my experience.

 

[Ranger188]

Thanks all. The one thing I noticed. The Norma has probably .065 jump from the lands. The loads I developed were very accurate. I am thinking my rifle may like a good amount of jump. Going to take it easy. Load the Accubonds with .020 jump and do a ladder test a few grains below max.

Right there, you said "My rifle may like a good amount of jump"
It's not the rifle that likes the jump, that particular bullet or load does and
the next load might not.
Don't get stuck on one thing working and expect the next to be the same.
Different case, powder, powder charge weight, bullet and primer will all have a affect on
on every load.
Even in the best rifle with another barrel (exact same as before), the load might be a .1 or .2
off in powder weight or bullet seating.

 

[USAFRet]

Right there, you said "My rifle may like a good amount of jump"
It's not the rifle that likes the jump, that particular bullet or load does and
the next load might not.
Don't get stuck on one thing working and expect the next to be the same.
Different case, powder, powder charge weight, bullet and primer will all have a affect on
on every load.
Even in the best rifle with another barrel (exact same as before), the load might be a .1 or .2
off in powder weight or bullet seating.

Very good call. Learning as I go. Thanks.

 

[209jones]

Very good call. Learning as I go. Thanks.

Now that you've measured bullets, you shud be able understand how there can be so much variance in OAL's, and that OAL is really only applicable to the mag length. The CBTO ( cartridge base to ogive) is the length that really counts, and the bullets also illustrate how that can change, then you get different guns, they will change again. Welcome to the mad, mad world of reloading and guns.

 

[Bill Norris]

Very good call. Learning as I go. Thanks.

In short the hand loading process is as deep and wide as you want it to be. Shooters from as far back as their beginning days of hand loading will tell you the rabbit hole never ends.

 

[Doom]

Thank you, Bill.

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

Most everyone at least once!

I'll add a couple of comments. As you noted your rifle may like jumping a bullet a fair amount especially with tangent ogive bullets. Remington 700 308's have so much free bore that a 168gr Matchking will not have the bullet shank in the neck if seated to the lands but shoots extremely well at 2.800". Put a 168 Berger VLD in and you will probably never find a good seating depth.

As for seating depths shown in the reloading data they are there as a variable that was used in testing the load. It may or may not be a precise load. Or you may find that a bullet has one recommended COAL in one manual and a different one in another. I have a 223 load that has about the same precision and POI at 100yds with a ~2.200" and ~2.250" COAL.