Stuck bolt/case on 300 WinMag

[IdahoSpud]

I just went to the range to work up a load for my 300 WinMag.

200 grn Berger hybrids with H1000 in GW brass that's on it's 3rd firing.


The very first shot at 75 grains resulted in the bolt being extremely hard to unlock. The case has a shiny angled ring right down near the belt.


I kept working up and didn't have it happen again until 1 shot at 77 grains. Still no other pressure signs.


Is this an issue with resizing? What's going on? Can I continue working up a bit more safely? Is this issue going to screw up my load development?

 

[Rathmatik]

Were these new cases or fired? If fired, did you bump the shoulders? After the first firing on belted magnums, it will headspace on the shoulders instead of the belt.

 

[huntnh]

Sounds like you need to bump the shoulder back a couple of 1000s. It’s happened to me on hotter loads and just neck sizing

 

[918v]

I just went to the range to work up a load for my 300 WinMag.

200 grn Berger hybrids with H1000 in GW brass that's on it's 3rd firing.


The very first shot at 75 grains resulted in the bolt being extremely hard to unlock. The case has a shiny angled ring right down near the belt.


I kept working up and didn't have it happen again until 1 shot at 77 grains. Still no other pressure signs.


Is this an issue with resizing? What's going on? Can I continue working up a bit more safely? Is this issue going to screw up my load development?

How are you resizing? How much is the case being sized?

 

[IdahoSpud]

This is shitty. They were fired twice out of an old rifle I no longer have so I tried full length sizing them back to Sammy specs this time. instead of bumping the shoulder I believe I just followed the directions on the die to fully size.

It only happened on two out of 25 rounds but it was pretty bad. It chambered easily.

Do you think I need to throw away all this expensive primed brass and buy new brass, or should not affect my load development that much?

 

[918v]

You should measure the diameter of the case body at where it expanded toward the bottom of the case and at the shoulder to make sure your die is sizing the case enough.

 

[Rocketmandb]

This is shitty. They were fired twice out of an old rifle I no longer have so I tried full length sizing them back to Sammy specs this time. instead of bumping the shoulder I believe I just followed the directions on the die to fully size.

It doesn't take much of a difference in the old chamber vs. the new and vs. the die to cause stickiness issues. If your new chamber is just a little small, you'll get what you're seeing.

 

[IdahoSpud]

Damn. That gunwerks brass wasn’t cheap but I just should canned it and bought 250 pieces of the Peterson brass. I really don’t feel like chasing my tail when I already struggle to develop a solid load.

 

[918v]

Could you please measure the case before and after sizing and tell us the dimensions.

 

[IdahoSpud]

Could you please measure the case before and after sizing and tell us the dimensions.

They are .514 after firing. They are .513 before.

 

[kingaling]

Whats headspace after firing and after resizing?
I have a R700 and RPR both chambered for 300 WM. In both of my rifles after firing the brass expands to a length of 2.274" (cartridge base to mid shoulder).I have 4 different brands of FL dies: Wilson, RCBS, Hornady and Redding. All of them cause the length to grow to a minimum of 2.276" no matter how far into the press I screw the die. They don't properly bump the should back. I had to file the shell holder down so that more of the brass would go into the die.

More dimensions would help in understanding the problem.

 

[918v]

They are .514 after firing. They are .513 before.

That’s the problem. RCBS makes a small base win mag die. Its a good investment.