So I bought a 300 Win mag. It is a American Rifle Company Nucleus with a Proof 300 Win barrel.

I have yet to fire a shot out of it.

I have been trying to size RWS once fired stuff I brought back with me from Germany.

It is all once fired stuff from a shooting cinema by the house. Didn't pay much for it, but I'd like to use it as I have a ton of it.

Set up the new Hornady dies to the manufactures specifications and put them together.

Used RCBS spray lube, and ran them through the sizing die.

Did a test fit in the rifle, and none of them will chamber. Should the sized brass chamber?

I usually have good luck with once fired brass, maybe this isn't something I can do with a belted case.

Yes, usually that works. But, you have a custom barrel with an unknown chamber.
Is it a base to shoulder length issue, or a radial dimension issue? Makes a difference.
Did you make your die set hard against the shell holder?
I have had to shorten dies a bit to compensate for a tight chamber. It is not unique to belted cases.
Try another make of die.
I had the same issue with 338 Lapua recently. I got another make of die and it worked fine.
Tolerances are quite generous among chambers, dies, and ammo; it is a wonder everything works as well as it does.

It is a Proof factory chamber for a Savage, since the ARC Nucleus has a Savage thread pitch and is set up to take Savage prefit barrels.

These dies are Hornady new dimension brand new dies.

I'll buy box of factory ammo and fire it so I can figure out the chamber dimensions and adjust the die for that. I would thank Redding dies would be the tightest.

Thanks again for all your help.

Do you want to cut a 1/3rd inch off and rechamber to 300 PRC?

You need to blacken a sized case with soot and try to run it into the chamber and see where the interference is. As dcpd said, sometimes it is at the shoulder but sometimes it is just ahead of the belt. They have dies to size the brass near the belt similar to a small base die.

Thanks gents I will try both of those things.

If you have a 300 PRC reamer I can.
I don't know what that is....
For blackening the brass, I use a felt tip pen. Much cleaner than soot, but that will work. Use a candle.

i will go with the common theme with belted cases not fitting another rifle even after full length sizing problem.

you need to size the case right above the belt.
they make a collet die for doing this.

full length dies don't do that, they can make the case shoulders short enough to separate the case above the web when you fire them, but it still wont chamber because of the belly bulge.

Big WW
If you want to try the magnum case collet resizing die let me know. I'll send it to you. If you decide to keep it pay what you think it's worth. If you don't want it, send it back. Small USPO flat rate box.

Dave

Another unlikely cause is too tight of a neck...

Will it chamber new unfired brass? If not, then the chamber might have been cut for very tight neck clearance and you will have to turn the necks.

quote:

Originally posted by Blacktailer:
You need to blacken a sized case with soot and try to run it into the chamber and see where the interference is. As dcpd said, sometimes it is at the shoulder but sometimes it is just ahead of the belt. They have dies to size the brass near the belt similar to a small base die.

I use a magic marker for this.

In tracking down some of my own challenges (er, blunders), I have found contact in interesting places.

The case mouth was perhaps the most interesting. The cases had stretched so much they were contacting the start of the chamber throat.

The more usual for me is the body-shoulder intersection.

Swelling just above the belt can easily happen for high pressure loads.

quote:

Originally posted by Big Wonderful Wyoming:
It is a Proof factory chamber for a Savage...

Does this mean it has a nut? What happens if you just back the barrel out a smidge?

Yes, the collet die that sizes right above the belt, check trim length and use Imperial Sizing Wax. If that doesn't do, run a new reamer up in that puppy, let your dogs breath! ha. 300WM is a fine cartridge too, I have never even seen a 300 PRC round, but I would not give up on the win Mag just yet.

quote:

Originally posted by jpl:

quote:

Originally posted by Big Wonderful Wyoming:
It is a Proof factory chamber for a Savage...

Does this mean it has a nut? What happens if you just back the barrel out a smidge?

Eh, not this one. It is shouldered and uses American Rifle companies BAR-LOC.

I assume it will chamber new brass or ammo? Have you checked?

Tony,

Yes it works.

Kind of sad on the RWS stuff not working.

I tried a collet base sizer and it only worked on 20 cases out of 100 that I tried.

quote:

Originally posted by nopride2:
Big WW
If you want to try the magnum case collet resizing die let me know. I'll send it to you. If you decide to keep it pay what you think it's worth. If you don't want it, send it back. Small USPO flat rate box.

Dave

Dave, you speak like a man with experience and who clearly understands the worth of this particular die.

BWW: Your problem is that your "full length" die's internal dimensions are, in some direction, larger than your chamber's dimensions. This isn't all that uncommon, especially with a custom chamber.

At the same time, your fired RWS brass was fired in a chamber (or chambers) which are larger than yours in some dimension. Unless and until you understand just which dimension (shoulder diameter, base-shoulder length, whatever -- it could even be belts which are too long for the custom chamber) the die is failing to squeeze back enough you won't know how to approach the problem.

IF it were simply a problem of being too long in the base-to-shoulder dimension then you could probably solve that by grinding a little thickness off of the shell holder head (or more radically, by grinding some metal off of the FL sizer mouth to shorten the die.) But you don't know that. So, first figure out just where the case is too large, then figure out how to reduce it to within the tolerances of your chamber. This may or may not require a new die or even a custom die.

Since it is designated as a "proof" barrel, I suspect it has a less than minimum SAAMI spec chamber, and since the usual dies are not meant for that, it is no wonder that they don't work. I would chamber it to a standard size, or order a special die.
And I am one who has never owned a collet die and will never own one. And have successfully reloaded magnum cases for many decades now.

It is a Proof Research barrel, not a "proof" test barrel.
https://proofresearch.com/barr...horn-origin-pre-fit/

You are probably right, I would bet it is a minimum profile chamber.

I use the collet did on all my belted cases, every time I resize.......when the area (just a few ten thousandths) ahead of the belt gets out of spec the round will still chamber, just be very difficult to extract after firing.

The collet sizer won't help your problem. Sounds like you have a nice tight saami minimum chamber and you brass was fired out of a sloppy saami max chamber.

Pitch it and get new brass, it ain't that expensive, or hard to find, don't add slop to your chamber IF you are working for accuracy. The win mag is not normally used for dangerous game after all.

I already did both those things.

Before you shorten the die, shorten the case holder with a file or whatever..If you cut away too much and new case holder is about $8.oo and die is maybe $35 ot $40...Its worked for me many times with a tight chamber..

I bought 100 rounds of Hornady Precision Hunter and ELD Match this last week. So I'll have new brass when I get the rifle back from the gunsmith. He is installing pillars and 338 CIP bottom metal

So I'll have 100 new cases. It would have been nice to salvage the RWS cases, but even after fighting with them in a collet die and trying 5 different magnum die sets with the mandrel removed, I am done fighting them for now.


I think it is like JTEX said, too big of a chamber in the previous rifle.


I have a ton of once fired RWS 30-06. I have already sized it and sent it to the old man to check in his Blaser K95. No problems.

I've had the same problem; usually with brass fired in a factory rifle that couldn't be sized for a tight chambered custom barrel. You could say I made my own problem and you'd be right most of the time.

The most useful tool I've found was a small base .300 Win die. With the stem removed it works on a number of other magnums as well and doesn't come near the shoulder. Some day I'll cut one in half so it will work on the longer and over 30 caliber ones as well.

I've also solved an issue for a couple of friends. One shot a BAR in .300 Win with factory loads and was quite happy to give his brass to another friend. Trouble is, he couldn't size it to fit his bolt gun. Once every couple of years I'll size a pile of it once and the second guy is good to go for the life of the brass.

After years of thinking nobody needed a Willis tool; I ended up needing one to salvage a pile of Weatherby brass. There's a bit of a learning to it; I ended up working in stages, feeding the case in a little more each time (relubing in between) until the cases were sized more than it at first seemed possible. When I tried doing it all at once they got good and stuck. I did find that as the die aged it burnished in and worked either.