You're having smithy issues, not load issues.
"...extractor keeps falling off..." As in coming off the bolt entirely or just not extracting? Two very different things. In any case, you have an extractor made for a rimmed case with a thick rim trying to extract a rimless case. The extractor needs to be modified or changed to extract the rimless case. You'll likely have to modify the bolt too.
Same thing happens when Lee-Enfields are rebarreled to .308.
Sure is refreshing to see a young guy building his own rifles. Be sure and thank your ma and pa for letting you. Most parents have coniption fits when their kid takes an interest in firearms.
