New lot of bullets are different length

[VTbluegrass]

I am nearing the end of a lot of Nosler 150g BT for my 270 and I opened a new lot just to check things out. The bullet base to ogive is 0.009avg longer in the new lot of bullets. The lots are separated by about 10 years so not knocking Nosler too bad on that. Would you make adjustment to seating die to account for this? It basically has stayed put for a few years now. This is where having to many reloading tools can make you over analyze things I think. I been rolling round with pretty good success just going by COAL and using a sharpie to determine jam length and just taking a smidge down. Now I have gauges to measure all this and I think sometimes I let myself get in the weeds instead of just saying pressures look good, ammo feeds smoothly, and is consistent.

I am leaning to just rolling and seeing if it still work like the old ones.

 

[Rifleman97]

I'd put one in a modified casing and measure it to the lands like you've never used one of those bullets before. I could be wrong but my guess is they changed the plastic tip in some way. The seating die shouldn't be touching the tip anyways, but rather the ogive which shouldn't be affected. Either way it's worth a check. At the very least you'll have an updated OAL for distance to the lands if you haven't done that in the past couple hundred rounds. Since lands are always being pushed back with barrel ware.

 

[Dmagna]

Just shoot them see what happens.

 

[Lonewolf74]

Rifleman, the op did state 9 thous longer base to ogive. If this is the case and he didn't mean overall length then I would indeed test a little bit. I would measure where you touch the lands with the old lot and new and seat the new lot at the same distance off the lands as your old lot of bullets. Shoot this and if happy with it leave it if wanna tune more I'd go .006-.009 in each direction in .003 increments and see which shoots best.

Or you can just do a complete seating depth test such as the Berger test and find your best overall length that way.

 

[VTbluegrass]

This was indeed bullet base to ogive difference and lucky it directly corresponded to CBTO in my modified case, just checked when I got home from work. In theory I got an extra 0.009 x case space for more powder. Haha.
I might just load a few without touching thing first then adjust my jump if she opens up. Not really pushing max pressure anyhow with 4831sc.
Guess there's one of two things about having more tools and knowledge. Either I would have blissfully unaware and kept rolling happily along or cursing why it changed without much of a solution.

 

[GLTaylor]

Start all over. Lot to lot difference is common. Hope you got a lot of the same lot number.
That's why competitive shooters sort their bullets!

 

[Rifleman97]

Rifleman, the op did state 9 thous longer base to ogive. If this is the case and he didn't mean overall length then I would indeed test a little bit. I would measure where you touch the lands with the old lot and new and seat the new lot at the same distance off the lands as your old lot of bullets. Shoot this and if happy with it leave it if wanna tune more I'd go .006-.009 in each direction in .003 increments and see which shoots best.

Or you can just do a complete seating depth test such as the Berger test and find your best overall length that way.

My mistake, I misread and didn't see that it was already measured to ogive

 

[VTbluegrass]

Start all over. Lot to lot difference is common. Hope you got a lot of the same lot number.
That's why competitive shooters sort their bullets!

I got 200 which for my 270 is enough to awhile and may take this barrel to the end of its life. I really want a reason to spin up an 8-twist 270, but I'm a ways out from justifying the expense.
This is why I run Bergers or Hammers in everything else. They just don't seem to vary enough to matter.

 

[The Oregonian]

If it were me I would seat it to where the CBTO was the same lot to lot, which sounds like it would be a die change of .009. Then I'd back off a grain or so of powder for a shot to test pressure, and maybe one .5 grains less than your current load. If those don't show pressure signs I would try your original load with the same CBTO and see what it does and adjust from there. You may not even need to adjust.

 

[Tiny Tim]

A lot has changed in ten years. Bullet profiles have changed even within the same model and brand, just like cars. Follow the advice of others. I'd likely set my CBTO to the same dimension of the other bullets and back off my powder charge and work back up. Hopefully this will get you back on track with the consumption of the fewest components.

 

[105Coues]

Nosier changed the shape significantly over the years but still labeled them the same. Just different box. I was shooting them for years and then all the sudden the shape changed. Even more concerning to me, they have made them not expand as rapidly as the originals so terminal performance changed. I started looking into it after a couple of instances of bullets going through a mule deer and elk without the expansion they used to have. I contacted Nosler more than once and no replies...... that being said, apparently they provide no customer service but I still shoot there bullets as they are a very accurate bullet. The earlier versions were much more suited to long range killing imo. The mule deer was a mature buck at 300 yards with a 270 win 130BT at 3000. Right behind the shoulder through both lungs. Why wife shot him and when we crossed the canyon and walked up on him he jumped up and ran about 80 yards and collapsed. Older style that never would have happened. My son shot a bull with the same bullet at 475 bedded several times in the chest and the bullets were going through to the other side but not expanding like they should have. The older ones were extreme killers. Not sure why they thought they had to change them since they already had partitions and accubonds. My .02

 

[QuietTexan]

You said you have gauges now, what are you measuring the CBTO with? Asking because if you're using the Hornady/ Stony Point or Sinclairs you aren't actually measuring the surface that engages the lands. You're measuring an arbitrary point forward of the engagement point defined by the size of your comparator insert. As an example, my 30cal insert is undersized and not concentric with a minimum of .280" and maximum of .293" (as I suspect all of them are because they're so cheap). The result is you are actually not measuring a change in the beginning of the bearing surface where the lands are engaged, but rather a change in a point along the profile of the ogive. This is a case where your older method of actually putting a bullet in the bore is likely more accurate because it measures the actual interface point.

The comparators works because there is a fixed relationship between your particular comparator insert and the beginning of the bearing surface for high-quality bullets with tight one-lot manufacturing tolerances, but that fixed distance does not necessarily remain constant lot to lot. Even if there was some high end comparator insert bored to the exact bore measurement of the caliber to measure a consistent engagement point, that measurement would vary between chambers and over the life of a rifle. So make it easy by removing as many variables as possible and measure the actual engagement of the bullet to the bore in this rifle.

I would use your original method to correlate the comparator CBTO measurements with actual lands engagement, and use that, not 0.009", as your change. Since you aren't at a max load, I'd probably just shoot a bracket around that new measurement, +/-0.005", and call it good.

Radical difference between Nosler 210 Gr Long Range and Hornady 208 Gr ELD-M

I thought the whole point of measuring the ogive was to measure the relationship between the bullets first point of contact and the lands. The CBTO measurement doesn't account for length of the bullet, bearing surface, or boat tail, all of which will make bullets behave differently. CBTO is...

www.longrangehunting.com

 

[Tiny Tim]

You said you have gauges now, what are you measuring the CBTO with? Asking because if you're using the Hornady/ Stony Point or Sinclairs you aren't actually measuring the surface that engages the lands. You're measuring an arbitrary point forward of the engagement point defined by the size of your comparator insert. As an example, my 30cal insert is undersized and not concentric with a minimum of .280" and maximum of .293" (as I suspect all of them are because they're so cheap). The result is you are actually not measuring a change in the beginning of the bearing surface where the lands are engaged, but rather a change in a point along the profile of the ogive. This is a case where your older method of actually putting a bullet in the bore is likely more accurate because it measures the actual interface point.

The comparators works because there is a fixed relationship between your particular comparator insert and the beginning of the bearing surface for high-quality bullets with tight one-lot manufacturing tolerances, but that fixed distance does not necessarily remain constant lot to lot. Even if there was some high end comparator insert bored to the exact bore measurement of the caliber to measure a consistent engagement point, that measurement would vary between chambers and over the life of a rifle. So make it easy by removing as many variables as possible and measure the actual engagement of the bullet to the bore in this rifle.

I would use your original method to correlate the comparator CBTO measurements with actual lands engagement, and use that, not 0.009", as your change. Since you aren't at a max load, I'd probably just shoot a bracket around that new measurement, +/-0.005", and call it good.

Radical difference between Nosler 210 Gr Long Range and Hornady 208 Gr ELD-M

I thought the whole point of measuring the ogive was to measure the relationship between the bullets first point of contact and the lands. The CBTO measurement doesn't account for length of the bullet, bearing surface, or boat tail, all of which will make bullets behave differently. CBTO is...

www.longrangehunting.com

These manufacturing tolerances on relatively cheap comparator, which measure an a slope, are to be used individually. You should not trust another person's comparator, even from the same manufacturer. ALWAYS use the same comparator to measure YOUR ammo as was used to determine the CBTO for your rifle. If you lose yours and purchase another, you have to start over. A difference of 0.0003" diameter on some if todays long sloped bullets may result on a significant change in OAL.