Zero 185gr JHP vs Nosler 185gr JHP

Looking for any input on the following problem......

185gr Nosler JHP over 4.2gr N310 fired out of a Springfield TRP with no problems at all.

185gr Zero JHP over 4.2gr N310 fired out of the same pistol malfunctions on virtually every round!! Failure to extract and failure to eject are the most common malfunctions. The seating depth for each round is 1.21 and the crimp is .469. Mixed lot of brass with Winchester and CCI primers.

From what I have been able to determine, the Zero 185gr JHP was designed as a replacement for the Nosler 185gr JHP. I cant understand why the Nosler bullets would function flawlessly, while the Zero's are nothing but trouble.....

Further testing revealed that I needed to load 4.4-4.5gr of N310 to get reliable functioning with the Zero bullet.

I am at a loss to explain this.........any thoughts?

Thanks,
Chris

4.2 is a light load for these bullets, 4.5 is the best, also 1.20 is the correct oal for noslers and i load my zeros the same. I have found that the V-310 of the last year or two is not as strong as what i loaded 5 years ago, then 4.1-4.3 was great, but with powder bought in 2011 they just dont work and i hAD to bump to 4.5 to get the same result. I have since discarded using 310 due its temperature sensitive nature and went back to bullseye powder. 4.4-4.5 sends either of these into the x ring

I load 4.0 grains of Bullseye with both the Nosler and Zero 185 HP's, the Noslers for the long line and the Zeros for the short. I use mixed brass and CCI #300 primers. No problems whatsoever with either combination. I load both on my Dillon Square Deal B interchangeably, without adjusting any die settings. I'm shooting a Kimber Eclipse Target II with a Kart barrel/bushing, a slide-mounted UltraDot, and a 10 lb. Wolff recoil spring. All loads shoot/function flawlessly.

I use Zero 185 JHP with VVN310 and have the best accuracy with 4.5gr. OAL 1.205 and crimp at .470. I'm using mostly newer Starline brass without any problems.

I did use 4.3gr of N310 for testing and did not have ejection problems, just accuracy was not nearly as good as the 4.5gr loads.