OzFclass

OK so whats the ideal/correct relationship between a match grade cut chamber, its resizing die and new brass? (at the case head)

Mine is 11.99 and 11.65.
In your second photograph the micrometer is in the wrong place --should be down at the point of transition from case body to shoulder.
Even so it would appear that your chamber is pretty right ( I know mine is ) as your measurements are not that different to mine.
I would look at the die.
Barry

I have just measured some cases from my rifle that I chambered with a PTG match reamer and it measures at the base 11.92mm and at the shoulder 11.67mm.
Try sizing and measuring a new case the die maybe on the small side.
Matt P

Norm,

Most of the various 6.5-284 FL dies I've had squeeze the head about 0.001 and the shoulder usually more, up to about 0.004. New brass measures about 0.001 smaller at the head end than resized brass. The 7 Shehane FL die is different for the shoulder where it only squeezes about 0.003.

Alan

AlanF wrote:Norm,

Most of the various 6.5-284 FL dies I've had squeeze the head about 0.001 and the shoulder usually more, up to about 0.004. New brass measures about 0.001 smaller at the head end than resized brass. The 7 Shehane FL die is different for the shoulder where it only squeezes about 0.003.

Alan

Thats what I would expect for the resize die but what about the chamber reamer?
I would assume that most chamber reamers are more than 0.001" larger than new brass case heads as new brass can vary so much from one maker to another.
I would expect about 0.005" clearance and the case head? This would mean that if you got a soft batch of brass and the case head expanded a few thou than you may have trouble sizing it back to specifications?

I say this as I am designing a reamer now for a custom chamber and the existing reamers that I have looked at for reference have varied quite a bit in this critical area.

Norm,

My 7 Shehane reamer drawing says 0.500 diameter exactly for a point 0.200 from the bolt-face, which is just in front of the extractor groove. My new brass measures 0.4975+/- at the same location. The CIP spec for the 6.5-284 Norma case at the same location is 0.5008. This is a Kiff reamer designed for Lapua brass. Hope this helps.

Alan

I spoke to the smith today and he seems to think that he has done the right thing and the chamber is to spec.

He dose not use a floating holder and said his lathe is true.
He pre drills and then reams by hand on the lathe.

This is not how I would do it but I am no expert on the subject.


During the phone call I had the thought of the brass being soft or hard.



JH

john,
a cerrosafe chamber cast of both the die and the chamber would dispell all doubts.
measure the cast 45 min after caasting. , as they change dimension.
it is available from brownells & sinclairs amongst many places.
keep safe,
bruce.

I just googled a few sites. This appears to be the common dimension: http://en.wikipedia.org/wiki/6.5%C3%9747mm_Lapua

After some thought I have chosen to butcher the die and see if i can gain an extra thou or so at the head,

I just spent a hour with it in the lathe and lapped the case head area using valve grinding paste.

Now the difference between a fireformed case and a FL sized at the head is 0.0007.

Cases are sizing with ease and I can now get the bump of the shoulder I needed.

Thanks for the help ! I few ideas here and there was the food for thought that I needed to resolve this issue.

Thanks Everyone for the help

JH



JH

John
Who is your gunsmith ?
Cheers
Paul

The rifle was chambered by Bob Taylor NSW

The rifle is a Savage F class that was in 6.5x284.
I picked the rifle up for $990 nearly new with 50 rounds fired.

Bob offered cheap work so I left him to rechamber to 6.5x47 in order to save the barrel.


I will chamber the next barrel for it. Just need the $$ for reamer and guages.


JH

Do you mean you rechambered the existing barrel for the smaller round, shortening the barrel slightly ?

I was just wondering if that makes it hard to guide the reamer and maybe the chamber is a little oversize...

I dont know, just asking ....

cheers andrew

Yes thats correct, its just the stock savage barrel.

It has gone from 30" to about 28"

I dont think that should effect things as the barrel was cut off after the old chamber. So essentially it was used as a barrel blank.

JH