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Ok, first day is now over with the project and this is what we achieved:

Chamber is reamed and lapped/polished, headspace is naturally checked and barrel is turned into profile and lightly polished (will be glass blasted to a matte finish later on). Basically this rifle would be now ready to shoot except that I'll take it a bit further before I put first rounds through it.

It was quite interesting job to put together a rifle with a cartridge this rare. I believe my biggest thing to worry about was the thing that basically all of the manufacturers involved in this project must have done things by the numbers and therefore I was a little suspicious if everything would fit into place that easily.

At first I thought that it didn't. First try with empty brass was a bit confusing. The case got stuck and had to be slightly forced to chamber. Not a good thing. My first assumption was that the reamer didn't have correct measures. After pondering back and forth I decided to add some colout to a case and turn it in chamber so I could see where the snug fit came from. I suspected the shoulder. Wrong I was. It got stuck from the side walls of the case. Now how weird is that.

I now head for the reloading bench and took three cases (.375, .400 and .458 Win) and pushed them through FL die. All three fitted the chamber with ease as rimmed cartridges usually do when everything is in order. What a relief. I have to admit that I was about to tape a 50 euro bill into barrel and throw the damn thing to river. That way I'd only loose 50 more euros...

Lesson here was that although QC cases looked like they were ready, they all had a systematic dimensional issue that confused us during the early stages of the project. Reason to this can be various. Either QC didn't have the correct measures or they have somehow during the manufacturing process created a bulb to the walls. More likely reason might be that the brass used must have been so elastic that it had bounced back a little bit and therefore the part that should have been straight was a little bit radiused. This is IMO a thing that doesn't normally happen with more common cartridges where cartridge go/no go gages can be used.

Oh, the best part. Feeding and extracting where there. Nothing will be changed or altered. Just as smooth and flawless as in my .375 and .300 H&H.

Barrel profile was borrowed quite ruthlessly from Ruger M77 .416 Rigby and only alterations were that I added just a bit weight to the rear and and took away from the front. This reduces the nose heaviness which easily botheres big rifles.

To be continued...