To my understanding, most gun smiths in this site will advice you against it. Many of them would be happy to build you a 338-300 RUM (338 EDGE) which is suppose to have just an edge over the LP using the 300 gr. SMK.
+1
The reason is not strength but bolt face size. If you open up the Remington and most other
bolts to accommodate the larger case head of the Lapua .588 and other large case heads (over
.600) the extractor becomes fragile because it has to be thinned to fit in the bolt. also the ring
arround the bolt is almost removed (Bolt Dia. is arround .700).
For the Lapua sized cases I recomend the Weatherby or custom actions with larger bolts and
longer magazines.
The SAAMI 338 Lapua does not have the case capacity of the RUM or the EDGE and has
no benefits other than better brass over the RUM and EDGE.
So if a person just wants a Lapua then I recomend going with a 338 Lapua improved and then
it is worth the cost and effort and will match or exceed the performance of the RUM or the EDGE.
If you are into reloading and fire forming then it is one of the best 338 rounds out there. Other
wise the RUM is strait forward and will perform well beyond the ability of most under hunting
conditions.
This is just my opinion for what it's worth.
PS: after posting I noticed a factory Remington for sale under the Guns for sale thread that is new.
it might be worth looking into.
J E CUSTOM