Pet 300 Win Mag Loads
- Thread starter xminerat
- Start date
Ok, is there any way around buying a headspace guage. I thought I could seat my die with the case at the top of the stroke and just set the die down until it kisses the shoulder plus a couple thou. But why will it not naturaly headspace of the shoulder of the once fired brass anyway? In which case just normal neck sizing would work.
JimOliver
New member
You will probably get lots of different answers to this question, but here's mine.......
First, if you are shooting a bolt gun, remove the firing pin, spring and whatever else you can easily remove from the bolt---Rem 700 and Win 70s are easy, don't know about others. You want to be able to feel the bolt close on the sized case without all the tension produced by the firing pin or striker spring.
Turn the size die down into the press, with the ram fully raised, until the bottom of the die is about 3/32 inch from the top surface of the shellholder. Size a case, clean lube off the case and try the case in the chamber; close the bolt, if you can.
The process is to size and try, slowly turning the die deeper into the press until the bolt closes with slight resistance.
In the beginning of this process, the bolt will close easily; as the die is screwed deeper into the press, the bolt closing will get more difficult. At the point that the bolt can be closed with very slight resistance, the die is properly positioned.
In the beginning, the shoulder isn't touched, but as the case body is sized more and more the shoulder actually moves forward very slightly. Then, you have to turn the die very slightly to position the shoulder corectly "for your rifle".
Rarely, I have had to grind a few thou from the top of the shellholder to let the die go deep enough to get the shoulder in the right place.
If you don't bump the shoulder just right, after 3 or 4 loadings, the shoulder will have moved forward enough to cause bolt closing to be difficult.
Additionally, the case/chamber size relationship is intended to allow the case to expand slightly to seal the chamber during firing. Then, the case contracts a bit to allow free extraction. If this sequence is prevented by improper sizing, stuck cases can happen, even with otherwise safe loads.
Sorry to describe building an atomic clock, just to tell the time.............
Jim
First, if you are shooting a bolt gun, remove the firing pin, spring and whatever else you can easily remove from the bolt---Rem 700 and Win 70s are easy, don't know about others. You want to be able to feel the bolt close on the sized case without all the tension produced by the firing pin or striker spring.
Turn the size die down into the press, with the ram fully raised, until the bottom of the die is about 3/32 inch from the top surface of the shellholder. Size a case, clean lube off the case and try the case in the chamber; close the bolt, if you can.
The process is to size and try, slowly turning the die deeper into the press until the bolt closes with slight resistance.
In the beginning of this process, the bolt will close easily; as the die is screwed deeper into the press, the bolt closing will get more difficult. At the point that the bolt can be closed with very slight resistance, the die is properly positioned.
In the beginning, the shoulder isn't touched, but as the case body is sized more and more the shoulder actually moves forward very slightly. Then, you have to turn the die very slightly to position the shoulder corectly "for your rifle".
Rarely, I have had to grind a few thou from the top of the shellholder to let the die go deep enough to get the shoulder in the right place.
If you don't bump the shoulder just right, after 3 or 4 loadings, the shoulder will have moved forward enough to cause bolt closing to be difficult.
Additionally, the case/chamber size relationship is intended to allow the case to expand slightly to seal the chamber during firing. Then, the case contracts a bit to allow free extraction. If this sequence is prevented by improper sizing, stuck cases can happen, even with otherwise safe loads.
Sorry to describe building an atomic clock, just to tell the time.............
Jim
These are my pet loads for MY 300 Win. Mag.
DO NOT USE THESE LOADS.
Case - Winchester
Primer - WLRM
Bullet - 180 Sierra Pro Hunter
Powder H4831 -- 77.5 GR.
DO NOT USE THESE LOADS
Case Winchester
Primer - CCI 250
Bullet - 180 Speer Mag. Tip
Powder - IMR4350 -- 73.3 GR.
These loads were worked up in the early 70's
Last loading of these were in the early 90's with 1970 vintage components. Still have one box of (20)each.
By the latest reloading books these loads posted are over Max.
They were NOT over max with components used.
I will have to rework both loads when I load for my 300 Win. Mag. again.
DAB
DO NOT USE THESE LOADS.
Case - Winchester
Primer - WLRM
Bullet - 180 Sierra Pro Hunter
Powder H4831 -- 77.5 GR.
DO NOT USE THESE LOADS
Case Winchester
Primer - CCI 250
Bullet - 180 Speer Mag. Tip
Powder - IMR4350 -- 73.3 GR.
These loads were worked up in the early 70's
Last loading of these were in the early 90's with 1970 vintage components. Still have one box of (20)each.
By the latest reloading books these loads posted are over Max.
They were NOT over max with components used.
I will have to rework both loads when I load for my 300 Win. Mag. again.
DAB
Last edited:
EJ Reichenbach
New member
Buy the hornady head space gauge, i dont adjust dies without it. Then try imr 4350 i shoot 180 AB. At 3250fps start at 72 grains i ended at 75. Shoots .65 inch groups at 100 yds, out of a factory rem.
