Load Data Discrepancy

[predatorhuntsnw]

I am fairly new to reloading (been at it about a year). I am currently working on developing a load for my .223 AR most specifically for Varmint hunting.
I currently use the 55gr Hornady Vmax factory loads. Due to supply issues and prices, i have started reloading using the 55 grain Vmax Bullets and found H335 to be the best powder for my gun.

I recently picked up a box of Sierra 55gr Blitzkings to try and see if it was similar performance etc. When i looked up the load data for this bullet i was very confused.
See my findings below.

HORNADY LOAD DATA - 55gr Vmax - .223 REM
H335

• Minimum charge weight: 20.8 grains
• Maximum Charge Weight: 23.2 grains
  • In my testing the best charge weight using this combo was 22.7 Gr. - no signs of pressure even at Max Charge

SIERRA LOAD DATA - 55gr BLITZKING - .223 REM *(AR-15)*
H335

• Minimum Charge Weight: 23.6
• Maximum Charge Weight: 25.7

The Sierra load data is stating that their minimum charge weight is MORE than the Maximum Hornady charge weight.

My questions are this:

1. Are two 55 grain bullets that drastically different that one could load 2.5 grains more powder behind a Sierra Bullet as opposed to a Hornady?
2. If I load a minimum charge weight using Sierra's numbers, I am OVER the MAX charge on Hornady's data - does this seem right?

 

[918v]

It depends on several variables.

A. Type of test gun
B. Proximity to lands
C. Case brand/volume difference
D. Primer
E. Bullet, powder, primer lot to lot variance

For example, if Sierra used an AR and Hornady a test barrel with a minimum chamber, that right there would account for the difference.

 

[Doom]

With the two “different “ bullet/brass combinations, the bullet manufacturers give a maximum charge that is safe, not necessarily a charge that is maximum SAMMI pressure. They often group multiple bullets of same or similar weight together and list the lowest charge weight for that group. Also Hornady seems to often publish loads that produce max velocities lower than others.