What is the normal tolerance on chamber diameter for a hunting rifle, ie diameter of a new unfired case compared to the diameter of the reamer.

Secondly, what is the approximate length for a throat on a typical hunting rifle, ie distance between the shoulder to the pilot. Can euro chambers have 20-30mm of throat.

George

Dimensions and tolerances for 9.3x64 are standardized by CIP. Diametral chamber tolerances from minimum are +,05mm (+.002"), which is virtually the same as SAAMI. Chamber length tolerance from minimum is +,1mm (+.004").

The throat extends 28mm ahead of the case mouth at approximately 0-degrees, 21-minutes of angle.

Maximum cartridge diameters are ,03mm (.0012") smaller than minimum chamber at corresponding locations.

Hope this helps,

Dave Manson

Hi Dave,
Thanks for your reply.
My gunsmith called me today and asked me if the reamer l supplied was a custom one. He basically told me that he cut the chamber and the reamer was a nice tight fit. He then put a new unfired rws case and found it a bit looser than he normally likes. So he measured up the base diameters and found there was 0.007" difference between the two. As you can imagine, l'm curious to determine if this is a show stopper. He also mentioned he thought the throat was on the long side, but l'm less worried about this as l was planning on using the heavier bullets like 320gr ones.
By the way, the reamer was one of yours.
Regards
George

Hello George:

Although some may think it excessive, having .007" clearance between factory ammo and a chamber cut to industry specs is not that unusual. If you compare SAAMI max allowable chamber to min allowable ammo, there's a potential difference of .011".

Would I want that much clearance in my rifle/ammo combination? No, I'd either make a reamer that matched my brass or shop around for brass that's a little larger. Likewise, I don't care for the European-style, long-taper throat and would likely modify the reamer to cut a throat closer to the bullet when the rifle's in battery.

Best regards,

Dave Manson

Once again, thanks for the reply Dave.
It is re-assuring to hear that it is within specification, even if it's not ideal.
I suppose l'll just have to wait and see how it shoots.
George

The brass is going to be a lot closer to the chamber specs after one firing. Then the question is, what dimensions will result when you resize the brass in your loading dies?

Both of my 9.3x64's have the European throating.

Does not seem to be an issue as they both easily shoot better than me.

quote:

Originally posted by ForrestB:
The brass is going to be a lot closer to the chamber specs after one firing. Then the question is, what dimensions will result when you resize the brass in your loading dies?

Yes, that is a very good question. We'll see what happens.Fortunately, l did order a neck sizing die when l got my dies from CH4D.l'm picking it up tommorow and the first thing l'll be measuring is the neck clearance with a seated projectile.Hopefully this is less than 4 thou.