Need some help ? I have two 1917's, one in 06 in a fajen stock, the 35 is in a fiberglass stock and the box has been modified to fit which puts the follower and spring at a slightly different angle (35 holds 1 less roundd than 06). Have tried o6 rounds in the 35 with no issue after 30 chamberings of dummy rds, hard to duplicate the 35 rounds in the 06 (can't chamber) so I can't say if there is or is not an issue (thinking shoulder angle). Have swapped spring and follower, no change, have lubed inside of box, no help, have swapped bolts, no help (marked so I got the 06 back with the 06). This happens one in 20 to 50 times I chamber a round, always at the worst time, speed in which I work the bolt does not seem to be a factor. Length is ok, and it does it on any bullet weight or configuration -200 cast to 250 spire point. Many of the times it does it on the round that is on the left side of the stack. I have compared bolt face contact to brass on the two rifles, seems to be the same (eyeball).
When it jams, the case is half way out of the box and the bolt drops contact and slides over the top of the round. Hope all this makes sense.
I have been over every inch of the receiver looking for a burr or anything that (limited knowledge) I feel is an issue. I am wondering if the issue is
bolt face contact/pickup of the round or if the modified shoulder of the round is catching on the hump just below the feed rails. Call me frustrated in NC because this rifle (when I do my part) can clover leaf 250's down to 200 cast(reloads) at 100 yrds when I do my part.

So, you have a 35 Whelen AI? You need to be clear here as case taper has a huge effect on feeding. The std 35 Whelen is nothing more than a .30-06 necked up. 90% of the time if the rifle fed correctly as a .30-06 it will do so as a Whelen. The improved cartridge is a whole different story, especially in a CRF action.

The shoulder is wider on an Improved cartridge, this can often lead to feed issues in an unmodified magazine. Unmodified meaning the magazine wasn't widened to match the increased diameter of the cartridges at the shoulder. Also, as Don Markey likes to correctly point out, that means matching the taper of the magazine with that of the "new" case.

z1R, the 35 Whelen is the improved version, I thought I had included that info because as you said, it is critical.

Besides the shoulder that is your problem; look at the front of the feed rails and see if they have been opened up to accommodate the larger neck diameter of the .35. That is why it feeds 06 and not 35s. Use a ball end mill, or a dremel ball and make the ammo sit in there neatly. They (especially an AI) won't feed in an unaltered 06 receiver.