I am reloading for my 300 min mag, and I have a problem that I hope someone can help me decifer. I just got done fireforming some new WW brass, I tumbled it, neck sized it, tumbled again, primed, weighed and loaded the powder charge and seated the bullets 5 thousandths off of the lands. But they will not chamber. They were all previously trimmed, chamfered, and deburred. The OAL is shorter than what I know will chamber in my rifle, and to make sure I took and case that I had just got done firing from another batch and seated the same bullet and it chambered.
I don't think the bullets and too close to the lands, but I am not sure what is going on. The case dimensions are the same as the manual and other previously fired cases.
What do you all think could be the problem?

Did you use a special "neck sizing" die, or a standard sizing die to neck size your cases ?

quote:

I just got done fireforming some new WW brass,

OK I got the feeling I am missing something here. WHy were you fireforming 300 WIn Mag? Were you using differnent cases you were converting?

Did you full length resize after fireforming, then trim your cases?

Try brass unsized, and after neck sizing. The
neck/ shoulder junction could be pulling forward.
Lube the case inside at the shoulder/ neck junction. Just a little Imperial Die Wax will do.
Good Luck!

My guess is you are fireforming to your chamber?? It could be your rifle likes the cases full length sized. It is od that one would work and not the other. Could just be a batch of brass that is not that great.? Norma makes some great stuff. You might just have to pull the bullet's, remove your decaping pin, and just run them back threw your full length die. If they dont shoot great that way just use them as fouling rounds. That does suck, hope you didnt buy to many.

I was fireforming to my chamber, I was using the RCBS lube on the necks and the inside. I guess the neck did streach anyway?

First thing to check is to see if the empty brass chambers. If it doesn't the "neck-pull" theory is where I'd hang my hat.

I'm betting, though, that the empty cases chamber just fine. My guess is that your seater die is screwed into the press too deep, and that you are deforming the hulls during seating. HTH, Dutch.

It sounds to me like Dutch hit this one on the head first. Try backing the die off at least an 1/8 turn, if not 1/4 then adjust the screw to get your seating depth. I would be cautious about getting to close to then lands right off. I usually find a good load a bit further back.( .015) If the die is hitting the neck enough to try crimping and there's no groove the shoulder will bulge. Nate

Did you trim your brass for length after they had been fired and neck sized. If not the brass may be to long and causing the problem. How did you determine the correct length for the OAL?

I use a Sinclair OAL Gage for my 300 win Mag. The only brass I have had a problem was with new REM Nickel brass they wouldn't chamber in my rifle they are too tight I needed a small base die to fix the problem. Instead I bought new Winchester unfired brass not nickel and have not had anymore problems.

Keep us informed I would like to know what you figured out to be the solution.

I pulled a losded round, and the case will not chamber. So I presume that I pulled the shoulder out on the case in the sizing process. That is about all I can figure it to be.
Thanks for all the help guys,
Charlie

you have to set the resizing die up correctly to bump the shoulder back so the round will chamber. I like to bump the shoulder back around 3 thousandths to chamber correctly. You have to try an empty case and try to close the bolt. It is best to disassemble the bolt when doing this so that the extractor won't make the brass cock one direction since the brass won't have a bullet in it. Check it and readjust your resizing die until the bolt closes on the brass nice and smooth. Once you have done this lock you die down and your shoulder will be bumped back the correct lenghth for your chamber.

I say all this assuming you don't have a chamber gauge for this gun. If you have a chamber gauge it is even easier.

quote:

Originally posted by Croberts:
I pulled a losded round, and the case will not chamber. So I presume that I pulled the shoulder out on the case in the sizing process. That is about all I can figure it to be.
Thanks for all the help guys,
Charlie

Just full length resize and the problem goes away. There no much to gain from neck sizing anyway. If you plan to hunt every round needs to chamber smoothly and this will always happen when full length resizing.

Too much variables to account for,give more info...