Brass Trim Length issue?

[Lbass]

I just recieved the 375 whelen improved barrel for my model 116. Used the Go, NO-GO gauges and everything seems to be right with them, Went to start prepping brass, Tried to chamber a sized case and it's very tight, when you pull it out it looks crimped. I checked the trim length in the book again and i'm under max.
Should I just keep trimming .005 off until it chambers properly?
How much can I trim under Max?
How much shorter will the brass get when fireformed if any?

P.S. I'm using the 35 whelen cartridge drawings, because that's all I can come up with, And Lyman's Reloading Manuel.

Thanks for any help.

[Lbass]

I did trim .080 off one of the cases and it chambers fine so I think i'm right on the neck length being the issue. Just not sure how to address it.

[mopar440]

are your guages for a whelen improved 40 degree shoulder or std whelen

[Lbass]

They are for the 40* improved shoulder. I've found the brass will chamber at 2.455, Lyman's book calls for 2.484 max. Will that have any negative effects?

[twarren]

I would only trim one then fire form it and see what you have. They will definately be shorter after fireforming.

[Russ]

Check here for drawing.
http://www.loaddata.com/members/search_detail.cfm?MetallicID=494