I can't help regarding Bartlett powders but I do have some concern regarding your questions. By "clone" do you mean a an exact copy (which a clone is), an equivalent, or a replacement/substitute for? They all have degrees of meaning which can be very different from each other.

An example of the first would be Winchester 296 and Hodgdon H-110. They are the same thing with different packaging. Load data for the one can be used for the other.

The second would be Alliant Unique and Hodgdon Universal. They are used for the same applications though load data may be different.

Lastly, Alliant Red Dot and Promo. They can be substituted for each other using the same powder drop weights though powder bushings would need to be changed due to differences in powder density.

Also, are you comparing several sources using Bartlett data or Bartlett data to several sources of Unique? If the latter it is most certainly a clue BR-5 is not a clone of Unique and would fall under the equivalent category as applications would be similar but utilize different data.

One could always do as suggested here and load up a few rounds and send off to be tested yourself. From there you would have another data point for comparison rather than speculation as it currently sits.

 

Thanks for the clarification and thoughtful reply. Bartlett says that unique loading data can be used for BR5. When i perused several souces and compared with them with the provided Bartlett data the Bartlett data was always lower

 

Different test facilities will have numbers different from each other. Testing the same loads on a different day or by a different technician in the same lab will also vary. Unless the results are over a hundred fps off or pressures a couple thousand psi off, I wouldn't worry much. As previously mentioned, load up a few rounds and send them off to be tested. Those numbers are likely to be different again but it will give you an additional data point for the Bartlett powder.

 

Do we have a recommended test faciity?

 

There are several with Tom Armburst, HP White, and Reloading Specialties commonly being mentioned on this site.

 

Tom Armbrust & Precision Reloading LLC are the two most used. HP White is no longer in business.

Tom Armbrust
Ballistic Research
1108 W. May Ave
McHenry, IL 60050-8918.
815.385.0037

Shop Rifle & Shotgun Reloading Supplies | Dies | Bullets | Hulls | Wads | Powder - Precision Reloading

Shop online for shotshell and metallic reloading supplies, shooting supplies, metallic presses, rifle reloading components, shotshell reloading components, shooting accessories, rifle reloading brass and Bullets.

www.precisionreloading.com

 

Kevin at Downrange also does shotshell ballistic testing:

http://www.downrangemfg.com/images/stories/ballistic_worksheet_2014.pdf