THe Nesika Model M can be modified to use a Wyatts 3.990" center feed mag box which is plenty for the 338 Kahn.
I have built several on the Chrome Moly Rem 700 receivers using this same mag box and they work great as long as the Kahn is loaded to proper pressures and not red lined. By that I mean if your getting 5-6 firings per case, your pressures are comfortable, if your loosing your primer pockets in 2 firings, your loading to hot!!!
If he goes with the Nesika, tell him to order the Hunter model. The standard round model will need to be modified as they have changed to a sako style extractor and this raises the ejection angle and the case will bind on the top of the receiver. With the Hunter model, the ejection port is larger and you can avoid this issue.
When they are available, the new Seekins DM system will allow 3.900" OAL as well and will work with most receivers with Rem 700 bolt spacing I believe so that would be a great choice as well.
The Stiller PredatorX receiver should also be able to me modified to accept the Wyatts center feed mag box. Most of these will only hold two rounds in the mag box with the Wyatts system. The Seekins is a 4 round Detachable Mag.
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