Rob or others,

I have had my .585 boltface cut to accept the .640 rim and as mentioned there is very little left on the rim. Firstly does the rim mean the larger bit sticking out from the bolt opposite the extractor or is it the thin lip surrounding most of the bolt ??

My next question is if that lip should shear off do I need to get a whole new bolt or can it be fixed and how. And what does the lip do any way ???.

When feeding rounds in your .585 should you feed reallt slowly as not to put pressure on this thin bit of metal.

Thanks, PC.

PC-The rim is the thin piece of steel still surrounding the bolt once it was opened up to .640 It's purpose is to control the amount of upward travel of the base of the cartridge as the case is cammed into the chamber during the loading cycle. You are correct in that there is not much metal left and this is why you can't build a T-Rex on a CZ550 Mag, for example, as the T-Rex has a .688 Case diameter and the bolt diameter is .700. There would be no metal left. You can get away with no rim on a T-Rex built on a 1917 Enfield action but only by using a P-14 bolt (also .700) as the opposing ejector ears are sufficient meaty to control the cartridge. When I built my NYATI, I recessed the boltface about .010 thousanths and re-case hardened the bolt face in order to beef up the rim area a bit. My rounds slip up into the rim with very little force and I've seen no problems with tearing off the remaining rim. You should be able to cycle your action quickly and decisively with no binding anywhere. The thicker and longer steel section of the boltface opposite the extractor provides support for the case during extraction and ejection. There should be very little force on the rim unless you have a case override during cycling! Check that there are no burrs on the rear of your extractor claw that may cause binding. Smooth it with a Dremel tool.
If your Rim tears off you are faced with either a very expensive re-weld/re-hardenening job or a new bolt. This is exactly why some people used the Rigby .590 boltface on their NYATI's. Unfortunately, they then ran into the predictable feeding problems associated with a severely rebated rim.

The only place on the bolt were I can see a problem occurring in my rifle rob is right beside the thicker and longer section of metal that supports the case rim during feeding. From the inside of the bolt right beside this section of metal it is the tiniest bit frayed, but not looking at it from the outside of the bolt. During building of it I sent him all your stuff and I think he may have followed prettty much everything you wrote including receesing the bolt .10 The reason i feel he did that is that looking at that thin metal from the outside it seems to bewell supported from the rest of the bolt. We will have to wait and see I suppose.

If it happened to tear off Rob, would I be better going for the rebated rim and getting the smith to get it to feed properly ??. It feeds flawlessly at the minute. If it shears off and I went for the rebated rim, despite setting up feeding would it still be as big a fix. If this happened I suppose I would have to pay someone to rebate all my cases to the Rigby Rim, as I do not have a lathe.

Thanks, Rob.

Rob,

I just had a thought if the shear of the thin lip of metal occured, would it be possible to slot the inside of the barrel and weld another piece of metal such as the longer section opposite the extractor to control the cartridge during feeding ??

PC- From the sound of it and all the info you gave to your smith I suspect he did a first class job and it will never shear off. If it does tell him to fix it for you at his expense! If there is undue contact use a Dremel tool and just polish the bevel of the extended section where it meets the bolt face. Don't grind anything as it is case hardened. You should not have any problems! This turned out to be a non-issue on mine.
By the way, I packaged up your NYATI Brass and will send it out tomorrow or Monday at the latest. Darn good looking stuff.-Rob

Thanks for all your help Rob, are you still coming to Australia in December ??

PC- Yes I'll be in OZ in December. I'll get some details together soon and perhaps we can get togther and down some VB stubbies!-Rob

Sounds Good Rob !.

Per577- I would not build a T-Rex I'd build a .600 Overkill. I will bet even money that a fully functional .600 Overkill can be built for under $2000 US. This will include the action, barrel gunsmithing and stock! The .600 Overkill will outperform the T-Rex and is purposely designed around commonly available actions. The problem of availablity of the brass is the same as Horneber and /or Bertram or someone else will manufacture it.-Rob

Rob,

If you could one day post or e-mail me a close up picture of your bolt face that would be appreciated.