Question on Alliant's CPRN Load Data

[BHogan]

Hello, 

 

I'm working up some 230gr XTreme plated bullets with BE-86, and I'm scratching my head on the charge weights I'm finding on Alliant's site.  They show CPRN as having the highest max weight, well above LRN and even above FMJ.  In fact, they've got CPRN higher than +P FMJ @230 grain.  I've noticed the same thing in their data for other powders and calibers too - the charge weights for the CPRN seem very high across the board. 

 

Per Speer's site the CPRN seems to be a garden-variety. .451 plated bullet vs their TMJ bullet which they say say should be loaded like an FMJ due to the much thicker plating.  Any insights into why the CPRN data are so loaded so heavy?  I asked Alliant but of course all they can say is that their data is specfic to that exact Speer bullet, so I guess the question is whether there's something unusual about the Speer plated bullets that leads to less pressure at an equivalent charge weight than other plated bullets:

 

 

[RePete]

When I loaded Xtreme bullets, I used FMJ data 

 

I have never used BE86, but I suggest that you load 10rds @ 10% lower that Alliant publish - that's their max - and chrono in your gun.

 

Increase 0.2 - 0.3 gr for the next 10.  Continue to the max if necessary.

[BHogan]

Thanks RePete.  So, i guess aim for that 7.1gr FMJ load as the max vs the 6.2 LRN, or 7.5 CPRN? What's even more strange to me in all this is while the Alliant Data is shows that LRN as a 6.2gr max load, in the Speer loading data they show the same bullet as having a 7.2gr max.  Same company, same bullet, a full grain difference between the two data sets, just has me nervous as something must be wrong.  I should probably get a chrono i guess.  I worked up some at 6.0 and 6.2, I might just keep going on up to 7.2 in .2 increments as you suggest and watch for whatever I can.

[K-Texas]

It would help if they showed the pressure ratings of the loads, but they aren't the only powder company showing higher charges for plated bullets. It's also the case in Western's data where pressure is also listed. When the various plated bullet makers said first to use cast lead data, and then some saying jacketed data is fine, slightly higher charges may, in fact, be the reality. Only pressure testing can tell us that and the smaller bullet-makers may not have that capability.