6.5x300 weatherby ?

[rmist]

Well...today I received the die set for the 6.5x300 Wby mag. My buddy brought the rifle over... it's a Sako AV action sporter. With a 29 in (I measure it...it's not 32") pencil barrel with porting on either side of the barrel looks like fish gills, it measures .490" right at the muzzle. He gave me a 500 box of Norma 139 gr full metal jacket boattails (No. 66513), plus a bag full of 139 gr Sierra HPBT's. Some 215 Fed primers and a pound of Retumbo. The cases look horrible and I put them in the tumbler. The carbon on the necks is really baked on. I put a couple in my lathe and used some crocus cloth on steel wool to get a look at them. It also looks like they may have been neck turned but they measure .0125", case oal is 2.790". It has a Leupold 4x12 scope, reticle has 3 horizontal cross hairs and a dot above the upper one, looks like 4 dots between the upper and middle cross hair. This is a all camo painted long range hunting rifle. Not a competition that I thought he might have been talking about.

So....with all the new info...what would you use as a starting point with the components I have on hand?
Thanx again,
Rmist

 

[wyoming .260]

I would guess that its in the same relative ballpark with the 26 nosler and there is pressure tested data for that. The old 6.5 -300 loads were pretty much all loaded with seat of the pants pressure indictators ,just like the 7 STW was. And as soon as pressure tested data showed up for it it died........... I would use quick load to find a starting load with similar powders that Nosler listed for the 26 and work up from there. JMHO.....

 

[rmist]

I was doing some more reading on this....seems like the shoulder was squared off later in life.... the cases I have are rounded. I can't tell by looking in the full length New die if the shoulder is sharp or rounded. I haven't tried it yet, don't really want to get stuck !!
With Retumbo where would you start using the 264 win mag data??
Thx again

 

[Patch700]

Your best bet at this point would be to take it in to a competent smith who can do a proper chamber cast..
Firstly you mentioned you measured neck thickness to be .0125" , this dictates one of several scenarios.

Firstly assuming this brass was matched to this rifle it's most likely to be of a tight neck variety as normal brass should have a neck thickness of around .014+ -.
It is possible that he turned necks for the sake of turning them and has now created .010-.011" clearance (not great)

If it is a 6.5x300 wthby then it will have the double radius shoulder.

Have you tried chambering a fired case that he supplied?

Have you tried re-sizing a piece of supplied brass and comparing measurements both prior and after?

I would be doing more homework before I started looking for recipes to a cartridge that has some important variables.

Good luck.

 

[Catfur]

Wouldn't this be closest to the 6.5 STW? I'm sure you can find some decent data floating around the net for that cartridge.