Please ID Chambering

[YLeeFoxx]

I need help determining a rifle's chambering.
My gunsmith did a chamber cast and came up with a case length of 1.775", body diameter of .474" and the bore is .266".

Below are pictures of the chamber and the chamber cast next to a 260 round.

Thank you for your help.

 

[spife7980]

What rifle/ is there a certain era we should be leaning towards?
.266 is weird, that’s the bore and not the groves, right? How sure are we that it’s not a .264?
Where is that body diameter .474 at, base presumably?

 

[918v]

I vote 264 Creedmore

 

[YLeeFoxx]

Yes, the case measurement is near the base. I believe the rifle was put together around 2000.

Could it be .264"? Yes.


Thank you for your time. I greatly appreciate it.

 

[Mike Casselton]

6.5x55 imp

 

[whatsupdoc]

Its shorter than a 6.5x47 Lapua. You sure case length is 1.775

 

[ma smith]

measure the shoulder length if possible, and the neck length if you have calipers.
that will really help match a saami or wildcat print, IMHO

 

[YLeeFoxx]

6.5x55 imp

Too short.

 

[YLeeFoxx]

Its shorter than a 6.5x47 Lapua. You sure case length is 1.775

Pretty sure. The gunsmith measured it.

 

[YLeeFoxx]

measure the shoulder length if possible, and the neck length if you have calipers.
that will really help match a saami or wildcat print, IMHO

I don't have the chamber casting.

Sorry for the trouble, but i appreciate the help.

 

[918v]

Pretty sure. The gunsmith measured it.

How do you know he measured it right? Take a 6.5 Creedmoor case and see if it chambers.

 

[YLeeFoxx]

How do you know he measured it right? Take a 6.5 Creedmoor case and see if it chambers.

 

[YLeeFoxx]

I have CM gages on the way. May have some ammo around and will check.

 

[YLeeFoxx]

Just checked and the 6.5 CM DOES chamber!

 

[YLeeFoxx]

Thank all of you for your help!

 

[spife7980]

Just checked and the 6.5 CM DOES chamber!

A creedmoor would chamber in a 50bmg.
Less than is not equal to. Just a word of warning. You need more than two measurements to match a chamber.

 

[918v]

A creedmoor would chamber in a 50bmg.
Less than is not equal to. Just a word of warning. You need more than two measurements to match a chamber.

True

So now we need to add material to the back of the case until the bolt is hard to close.

 

[Rodney65]

In all my years of shooting I don't know I have ever heard of someone having this problem. It is a problem nonetheless and I appreciate the steps you are taking to sort it out. I hope you get it figured.

A creedmoor would chamber in a 50bmg.
Less than is not equal to. Just a word of warning. You need more than two measurements to match a chamber.

If it was a .264 bore and the chamber was at least really close to a 6.5cm would it not just fireform the case? Not saying OP should do this I'm just wondering.

 

[918v]

Well, if the chamber is too long it might separate at the case head.

 

[spife7980]

If it was a .264 bore and the chamber was at least really close to a 6.5cm would it not just fireform the case? Not saying OP should do this I'm just wondering.

Hopefully… but as 918 said it can separate at the case head or depending along the diameters (we only have the base to go on) it could rip longitudinally as it expands radially. If a creed fits it’s not too likely that the body taper would be different enough, like if a 22-250 was what fit… but we can’t know that with only two numbers.

 

[ma smith]

Any chance the 264+2=266 is the allowance for a throat lede?

 

[918v]

Possibly. Cerrosafe shrinks after it cools. I think you have to do math involving % to get an appropriate true number.

 

[Mike Casselton]

I'd also have a concern with the unmarked barrel, combined with all those chatter marks on the back of the barrel.
Maybe it really is a .264, but the smith just let the tools wobble around a bit.

I say pull the barrel and then go from there with inserting different 6.5 caliber cartridges.

Or, even better, get the chamber cast and re-measure all of the data points.

It'll take 5 minutes to figure it out from there.

 

[sirhrmechanic]

I’m with Mike Castleton on this.

The chatter marks at the back of that barrel are appalling. And the fact that it’s not marked is another ding against whoever chambered and installed it. You never install a barrel without marking it.

That said, have you taken the action out of the stock to see if there is a marking underneath? If the Gunsmith didn’t have a really good set of stamps or engraver they might have marked it underneath in a discreet area.

But until you really get a set of chamber measure measurements and honestly look more closely at that barrel, I would be really cautious, assuming nothing before shooting it.

The good news is once you figure out a caliber you may well be able to just have the barrel cut back a bit and re-chambered with something new. You can always take a little bit off the chamber end.

Cheers and let us know how it turns out.

Sirhr

 

[sirhrmechanic]

And what’s going on here?

It almost looks like the action is cast and loaded with porosity? Or has it been peened?

Post some more pictures of the rifle if you get a moment, OP. Definitely interested in seeing the whole package so to speak.

Sirhr

PS. Looks like you have it out of the chassis or stock already, so my question about looking for a stamp underneath is probably moot!

 

[ma smith]

I think I found it...

 

[CaptNemo]

Looks like 6.5-284 Norma ?

I shoot a Tikka T3X chambered in .284 Winchester and that cast looked really familiar...

 

[Rocketmandb]

Pretty sure. The gunsmith measured it.

Then the 6.5 CM case wouldn't have chambered.

EDIT: One way to validate if it's a 6.5 CM is to get both go- and no-go gauges and see if they chamber (or don't) correctly. Still, as others have said, that machining looks pretty bad.

Is there sentimental attachment to this? Was it given to you? I'd be inclined to get a new barrel chambered in the short action caliber of your choice.

 

[Rodney65]

And what’s going on here?

View attachment 8694479

It almost looks like the action is cast and loaded with porosity? Or has it been peened?

Post some more pictures of the rifle if you get a moment, OP. Definitely interested in seeing the whole package so to speak.

Sirhr

PS. Looks like you have it out of the chassis or stock already, so my question about looking for a stamp underneath is probably moot!

How could that even happen? The rest of the cuts look awful too. Honestly this isn't something I would think it worth paying a smith to touch or even messing with really.

 

[cas6969]

I'm gonna go backwards and unscientific.... what is it?

My wild ass blind guesses if it was a Type 38 Arisaka will be different than my wild ass guesses if it's a NULA Model 20 for example.

 

[roostercogburn98]

Possibly. Cerrosafe shrinks after it cools. I think you have to do math involving % to get an appropriate true number.

It shrinks as it cools over a period of 30 minutes, then starts to expand again . An hour after you cast it, the piece will be exactly the same dimensions as the chamber. Sad thing is that it continues to swell for some time and will end up bigger than the original cast.

OP, if your gunsmith measures too early or too late, the measurements are off

 

[918v]

It shrinks as it cools over a period of 30 minutes, then starts to expand again . An hour after you cast it, the piece will be exactly the same dimensions as the chamber. Sad thing is that it continues to swell for some time and will end up bigger than the original cast.

OP, if your gunsmith measures too early or too late, the measurements are off

That might explain the .266” number

 

[Aftermath]

Agree with several others here.
I'd determine bore and decide upon a chambering for rechamber.
In reality, I'd be far more likely to just buy a new barrel, start from scratch and know for certain what I had

 

[YLeeFoxx]

Have 6.5 gages on the way.

 

[Mike Casselton]

I would pull the barrel to do any further testing.

Then I would probably call Northland SS and order a $375.00 barrel for it. You'll be miles ahead of whatever you're doing right now.

 

[secondofangle2]

What is the goal of this entire enterprise?

By now, the whole thing could’ve been rebarreled in whatever caliber you want. Accounting for making a cast putting it on snipers side getting everyone to weigh in, taking it to your gunsmith and all of that.and why the heck would we want to make a cartridge selection based on some random unmarked barrel action we have laying around Anyway? This sounds like some kind of sunk cost bias or Pennywise and pound foolish exercise to me.

Seriously, I am truly curious as to what the point is

 

[Mike Casselton]

Since the OP is from Manchester, TN we could be related, so I gotta at least try to be nice.