I love the Ackley rounds...had a 35 Whelan AI for over 20 yrs. However, they are super easy to load too hot and not even know it! My favorite loads, and ones that I killed a lot of game with, ran on the heels of the 358 Norma Mag! I saw no "regular pressure signs, i.e. sticky bolt lift, flat primers, or ejector marks", but I was tickling 72K in a round that should not have been loaded higher than 62-65K! So, get you a 24" barrel and ream it to the standard Whelan. Use R15 and have a ball! It is a killer deluxe...less recoil but acts like a 338 win mag on game! And you don't need to replace the factory lug. That is really only helpful on big diameter, varmint weight barrels, and iffy at that! Do have your action Blueprinted/trued and pillar bedded when you get it rebarreled. Its worth the money.
I agree with having the action cleaned up and blueprinted although I would insist on having a new recoil lug added to the build. The new recoil lugs are ground flat and you can have one just ever slightly bigger for almost no money at all. If you're getting the action/bolt blueprinted, get a new lug!
I've only had one rifle built that I had the oversized lug put on. It was a Mod 700 6mm Remington in a varmint weight barrel. I have had many rebarreled Mod 70's, mostly Mod 700s. I've had several other actions from Mausers to Sakos pillar bedded/trued up and always used their recoil lug as well. I can see where a rifle made up for Long Range or Benchrest could benefit from every little bit of machining to make it accurate. In a "Sporter" weight, hunting rifle, especially in a cartridge like the Whelan, I could never tell any difference keeping the factory lug. Now, I need to add that I am not a bonafide Long Range hunter, my furthest shots have been right at 375yds on big game. I did kill an unlucky rabbit at 405yds with a Bushmaster Predator 223 once, ha. I certainly am not saying "don't do it", ha, its just for me, and I probably should have said that, it isn't necessary. It is much easier to use one when having a new barrel put on at the same time, of course, and they are cheap as dirt, somewhere around $40 each. It may give you that bit of 'panache", help your confidence level.
On the advice from here I am buying a new barrel. For my 700 06 to convert to 35 whelen. Should I go Ai or standard. Pros and cons. Replace the factory recoil lug?
As others have said, the AI is not necessary but it does give you more case volume and a more efficient powder burn and longer brass life. so this decision is yours. dies for ether round are very easy to find, so that is not a problem.
If a 35 Whelen head space gauge is used to head space the chamber, standard 35 Whelen ammo can be use and fire formed with great accuracy while hunting. Magazine length ammo can be used and you will give up nothing.
As far as the recoil lug, Always replace the factory recoil lug because they are NEVER perfectly flat.
The 700 Rem uses a .187 recoil lug and I recommend replacing it with a ground aftermarket lug of .200 to .2285 because they are more than strong enough. Thicker recoil lugs are not necessary and some times weaken the stock because the recoil slot in the stock has to be opened up to except the thicker lug.
As posted, have the action blueprinted and you wont regret it.
Measure a stock recoil lug with a dial indicator. The needle will look like its on the ocean, up then down, up, down.
For under $40 its a no brainer. I can't imagine a smith even building without a real lug. If the smith I was using didn't INSIST on a new lug......I would probably look for a new smith AND lug.
Remember the advice you are giving that you got off of the internet and don't REALLY KNOW works might cause a miss or a wounded animal or a dead hunter. Please for the sports sake be 100% sure when you post something.
Per the NRA "long range STARTS at 600".
While I can appreciate the viewpoints on new, thicker lugs, I still can't see what I have lost by going with the factory lug? I mean, my rifles are .5 to .75" shooters with several loads, and I have been doing that since my first rebarrel ( a 30-06 Douglas on a Mod 70 FWT Classic) back in '94. At least, for "me" I can't tell any difference in the field. But I will say again, for $40 or so, on a new barrel job, heck, why not? Its certainly not something that will "hurt"...