Conflicting Published Data

[HARV6]

Gotta love it when you find published data that makes you scratch your head. In looking for a good hunting bullet to bring out the best of my 25-06 I read several praises for the 115 Nosler Partition. After buying 4 boxes of them I looked into my Nosler #6 manual and noted with all Nosler115 grain bullets Hodgdon's Retumbo should deliver maximum velocity of 3170fps w/ 57.5 grains. Good, I've got Retumbo already! I check Hodgdon's website. They don't have info for a 115gr bullet but they do have it for a 117 grain which should be safe to use. They list 60.5 grains as max w/ 3079fps..... Huh?
So then I start to look deeper...
1. Barrel length? Both used 24"
2. Nosler lists the SAME charge of 57.5 and 3175fps as max for it's 120gr partition...huh?
3. Nosler lists 59.0 and 3267fps as max for it's 110 Accubond.

In my mind, it looks like Nosler just took the max charge they found for their 120 partition and used it for their 115 partition as well. So what I decided to do was find the middle ground between Nosler's 110 and 120 data. Comes out to be 58.25gr. @ 3221fps.

Last night I loaded them up. Dropped back to 55.5 as a starting charge, and in 1.0 grain increments stepped up to Hodgdon's max of 60.5. Luckily I have a chronograph and will stop @ 3200fps or pressure signs. I've never loaded my other rifles hot enough to find pressure signs. Kinda nervous about that, but with such conflicting data, seems like it's time to learn. Any advice?

 

[CarJunkieLS1]

Hodgdon has a 60.0gr compressed load as max using a 120gr spire point. COAL is 3.160.

Starting at 55.5 I believe you will be safe and it might be a good idea to use .5gr increments when working up loads.

Also the partition bullet is longer than most other bullets or the same caliber and weight so that may be why you have some data differences.

 

[spitballer]

I'll be the first to admit that I view published loading data with some skepticism. Nevertheless a lot of work went into that data and it's all supposedly empirical, so published maximum loads should be safe.

I would note that pressure increases as bullets continue to be fired. An example would be the 4198 I started on a couple of weeks ago. A certain combination gave me excellent results right off the bat, but 15 rounds later my velocity was 108% of the starting rounds. Pressure was no doubt even more than that.

 

[JimKirk]

The problem is neither of the companies used "your" rifle to develop their data... you will find that rifles are like children... each is different... that is the reason they list a starting load ...

I see that you are using a chronograph ... that is one of the better tools for a reloader to have ... I have a never found much data that matches what I get from my .25/06 and chronograph....