300 wm new barrel chamber question

[briang7511]

ive got a new barrel on my 300 win mag and the brass I was using and some once fired brass that I bought does not fit in the chamber. Ive only used FL dies and when I tried lowering the die to bump the shoulder back the die bottoms out. New ammo loads just fine. since the new chamber is tighter is the once fired brass I have no good or is there a way to bump the shoulder back?

 

[HodgdonExtreme]

First thing you need to do is determine if you have a body diametral clearance issue, or a datum-length clearance issue.

Measure the length from casehead to shoulder (I know belted cases "headspace" off the belt, but don't worry about it) on a piece or two of brass that has been successfully fired from your new chamber.

Then measure that same length on some of the old chamber fired brass that won't fit in the new chamber.

Is the old chamber brass longer than the new chamber brass? If so, you can sand down the top face of your shellholder to achieve more sizing on your brass.

If not, then you will need a body die capable of sizing the body's diameter down a little more.

 

[anarchist]

It may not be the shoulder. Have you measured the once fired brass just above the belt? Could be that this is your issue. The Larry Willis collet die is supposed to take care of that. You can also take the decapping stem out of your sizing die and run it down on a loaded round. Resize one of your once fired cases. If it still won't chamber, most likely the the other problem.

 

[briang7511]

First thing you need to do is determine if you have a body diametral clearance issue, or a datum-length clearance issue.

Measure the length from casehead to shoulder (I know belted cases "headspace" off the belt, but don't worry about it) on a piece or two of brass that has been successfully fired from your new chamber.

Then measure that same length on some of the old chamber fired brass that won't fit in the new chamber.

Is the old chamber brass longer than the new chamber brass? If so, you can sand down the top face of your shellholder to achieve more sizing on your brass.

If not, then you will need a body die capable of sizing the body's diameter down a little more.

the one piece of brass I tried to chamber a few times did have some scuffs on the shoulder. I will try again later but I don't believe the body to be too large.

I have a friend that has a grinding shop and can set up on a surface grinder and grind the die down.

I will measure the once fired brass just above the belt as well. ive got 300 pieces of brass that im hopeing to use. if not its someones lucky day

 

[briang7511]

If a single stage, have the shell holder ground (cheaper to replace).

Take a sharpy and mark the body from the belt, up about an inch. Try to chamber and see if you have rub marks on the sides.

Typically 300wm FL die will reduce cartridge headspace much more than needed (to allow clearance to space off the belt), so I would suspect it's the case body that's the issue.

definitely grind the shell holder, good idea. I will mark it with a sharpie also and see what happens. thanks for the help.

 

[cotntop]

Had the same problem and the Larry Willis collet die fixed that problem.

 

[918v]

Try lubing the inside of the neck so the expander ball doesn't drag on it. It could be pulling the shoulder forward and changing the angle.

 

[Long Range 338]

I'm sorry did u post something? I was too busy ogling your avatar to pay attention! Sorry but the hot blond caught my attention and I couldn't resist....


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[briang7511]

If a single stage, have the shell holder ground (cheaper to replace).

Take a sharpy and mark the body from the belt, up about an inch. Try to chamber and see if you have rub marks on the sides.

Typically 300wm FL die will reduce cartridge headspace much more than needed (to allow clearance to space off the belt), so I would suspect it's the case body that's the issue.

after further inspection of a new and a once fired and resized case I found that the die does not appear to go all the way down to the belt and is leaving a step before the belt. I used a sharpie and marked a case and only right at that step is the black mark gone. it is about .025 long from the belt.

question is will grinding down a shell holder down that same .025 fix the issue? Or will a willis collet die be a better answer?

 

[supercorndogs]

yea the willis collet die is the way to fix the problem. also if the rounds are not loaded so hot they will do this much slower. i have some 300 wm brass i have fired 7 times without having to use a willis collet die 208 amaxs and 210 bergers at 2746 sd of 8

 

[longshooter]

What is your distance from breech face to shoulder in the chamber? If it is too short, perhaps it needs to be lengthened.

 

[918v]

Is the belt area where the case binds in the chamber? The collet die will not enable your standard die to bump the shoulder more.

 

[sakobob]

op measure the diameter of the brass .040-.070 above the belt,
the problem is probably in this area.grinding down a shell holder most
likely won't solve it, the case will bottom out on the belt and still not size the case to the correct
size.you need to be in the .509-.511 diameter above the belt.
as said the willis die is the hot ticket if your going to be shooting a lot of wm, or
send off some new once fired cases to a die manufacture for a custom die.