Correct staggerfeed magazine lip geometry for 35 Whelen?

I am having feeding problems with my long action staggerfeed 35 Whelen (originally, a 270). Rounds are jumping out of the magazine prematurely as I push the bolt forward. Of course it only happens at the range, not with dummy rounds on the workbench.

Does anyone know the correct magazine lip geometry in front and rear?
I thought I remembered Sharpshooter mentioning it in a thread, but my search force is not strong and I have not been able to locate the posting.

I am presuming the measurements are the same for 270 and all the -06 variants, including 35 whelen, but if this is not the case, I am certainly open to learning the truth.

I am standing by to be educated and I thank you in advance for your assistance.

I too will wait. It seems e eryone has always tweaked and tried.