First time resizing brass & over did it...now what?

[Guinness]

Hi all,

New reloader here and I re-sized my once-fired 300 Win Mag brass this weekend. I set up the Forster full-length re-sizing die according to their instructions and went to work. Unfortunately while I was measuring the cases with a bump gauge I brainfarted a decimal place. I was hoping to set the shoulder back what I now know should be 0.002" and ended up with 0.01 (which in my brain at the time was 0.001") so I kept going.

Once fired brass bump gauge measurement - 2.2270"
Re-sized brass bump gauge measurement - 2.2170"

So now I've got brass that, at best, has been overworked this time through the press. What are my worst cast scenarios from those with experience? Excessive headspace? Lack of accuracy and/or useless info from all shots using these cases? Long necks that will require trimming sooner than if I hadn't made this mistake? Please give me all your opinions.

And lastly, I want to avoid this situation in the future so what changes do I make? Like I said, I set the die up according to instructions and had a nice cam over at the bottom of the down stroke. The whole process went off without a hitch. Do I simply back the die out 0.008" in order to achieve 0.002" shoulder set back? My brain tells me its this easy but I hate mistakes and this one is enough for now.

Thanks for any replies.

G

 

[Rich Coyle]

Last paragraph first. Move the die out at least twice as far as you think you need to. A full turn is about .070". With this info I think you need to take a fired case that you have not sized, lube it, size it full length, clean it and try it in your rifle. It might show a slight bolt resistance on closing. If it does you have a good start. Turn the die down about 1/20th of a turn. This gives you about .003" shorter length. Try another fired case. Repeat this until the first one shows not resistance and try one more. If it is the same lock it down. You are not headspacing on the shoulder with only a couple thousandths clearance.

The others I would anneal, load, and fire them. From my experience they will not be as accurate as they can be, but good enough for some off hand practice.

 

[Rick Richard]

Last paragraph first. Move the die out at least twice as far as you think you need to. A full turn is about .070". With this info I think you need to take a fired case that you have not sized, lube it, size it full length, clean it and try it in your rifle. It might show a slight bolt resistance on closing. If it does you have a good start. Turn the die down about 1/20th of a turn. This gives you about .003" shorter length. Try another fired case. Repeat this until the first one shows not resistance and try one more. If it is the same lock it down. You are not headspacing on the shoulder with only a couple thousandths clearance.

The others I would anneal, load, and fire them. From my experience they will not be as accurate as they can be, but good enough for some off hand practice.

Yep. Good advice. If it is new or once fired brass, you may get by without annealing.

 

[Laelkhunter]

Would you guys recommend a reduced load (not max) ? Maybe he can shoot them so that it would be the same as "fire forming" them to his chamber.

 

[Gunpoor]

I have had a similar experience and my advise is to just load and shoot them, and learn from your mistake. Unless the brass cases have had many firings they are usually forgiving, at least for a one time boo-boo.

 

[Dosh]

G, perhaps a minimum starting charge from your load manual to fireform the brass. Reducing charges too much is a bit dangerous. With the exception of Lapua, most other brands could use annealing right out of the box. Good luck

 

[Laelkhunter]

G, perhaps a minimum starting charge from your load manual to fireform the brass. Reducing charges too much is a bit dangerous. With the exception of Lapua, most other brands could use annealing right out of the box. Good luck

That's what I meant, a reduced charge but at least a minimum starting load. I would use caution with a reduced load, especially with slow burning powders.

 

[rcoody]

I have had a similar experience and my advise is to just load and shoot them, and learn from your mistake. Unless the brass cases have had many firings they are usually forgiving, at least for a one time boo-boo.

+1

300 mag was designed to headspace.off.the.belt anyway.

Common practice is.to headspace off the shoulder after the.first.firing for brass life. Truth is it probably takes about 3 firings before that brass is fully fireformed

This mistake will not be good for brass life but it will be fine. Just watch for the bright ring above the belt.

 

[Guinness]

So, I've got the die set properly (thanks Coyle) and the proper measurements in my notes so I'll chock this one up to inexperience and watch the brass closely expecting that it goes south more quickly than if I hadn't goofed up.

Thanks for sharing all of your advice, insight and experience.

Regards,

G

 

[MagnumManiac]

Hi all,

New reloader here and I re-sized my once-fired 300 Win Mag brass this weekend. I set up the Forster full-length re-sizing die according to their instructions and went to work. Unfortunately while I was measuring the cases with a bump gauge I brainfarted a decimal place. I was hoping to set the shoulder back what I now know should be 0.002" and ended up with 0.01 (which in my brain at the time was 0.001") so I kept going.

Once fired brass bump gauge measurement - 2.2270"
Re-sized brass bump gauge measurement - 2.2170"

So now I've got brass that, at best, has been overworked this time through the press. What are my worst cast scenarios from those with experience? Excessive headspace? Lack of accuracy and/or useless info from all shots using these cases? Long necks that will require trimming sooner than if I hadn't made this mistake? Please give me all your opinions.

And lastly, I want to avoid this situation in the future so what changes do I make? Like I said, I set the die up according to instructions and had a nice cam over at the bottom of the down stroke. The whole process went off without a hitch. Do I simply back the die out 0.008" in order to achieve 0.002" shoulder set back? My brain tells me its this easy but I hate mistakes and this one is enough for now.

Thanks for any replies.

G

Firstly, it's impossible to get excessive headspace with a belted case, the shoulder is irrelevant. Seeing this was once fired cases, you are good to go to load them and shoot them as is.

To adjust your die correctly, screw it in until firm contact with the shell holder, then back off a turn, size a case, clean, chamber it and 'feel' how much resistance there is. At this setting, it should be almost impossible to close the bolt, the case will be to long in base to shoulder measurement.
Continue this in 1/12 turns IN until a case is just snug enough to have some resistance on closing the bolt. Now measure that case against a fired case and adjust until you get the desired .002"-.003" shoulder bump.
To get 1/12 indexes on your dies, simply mark a white line on your lock ring corners, then again halfway between those points, I measure the halfway point and set my vernier to make it easier to mark. 1/12 turn equals about .006".

Cheers.
gun)